RADIANT HEATING DEVICE AND HOB COMPRISING A RADIANT HEATING DEVICE OF THIS KIND

Abstract

A radiant heating device for a hob has a sheet-like carrier with a carrier surface on its top side on which an electrical heating element runs in a meandering manner within an outer edge. A single temperature sensor is arranged in a temperature sensor housing which is arranged above a region which is free of heating elements. The temperature sensor housing covers the temperature sensor at the top and to the side and encloses the said temperature sensor in all directions. The temperature sensor housing is designed so as to be electrically insulating and thermally insulating at least at the top and to the side, wherein the said temperature sensor housing consists of an inner electrically insulating insulation housing part with the temperature sensor therein and an outer surrounding thermally insulating insulation housing part.

Claims

1. Radiant heating device having: a sheet-like carrier, said sheet-like carrier having a top side with a carrier surface on said top side, and having an outer edge, at least one electrical heating element, said electrical heating element being arranged so as to run on said carrier surface, said outer edge surrounding said carrier surface, wherein all of said electrical heating elements are arranged within said outer edge, a temperature sensor, said temperature sensor being arranged higher than said carrier surface, wherein: said outer edge has an outer side, said temperature sensor is arranged within said outer side of said outer edge, said temperature sensor is the only temperature sensor of said radiant heating device, said radiant heating device has a temperature sensor housing, said temperature sensor being arranged in said temperature sensor housing, said temperature sensor housing covers said temperature sensor at a top and to a side and encloses said temperature sensor in said directions, said temperature sensor housing is designed so as to be electrically insulating and thermally insulating at least at said top and to said side.

2. Radiant heating device according to claim 1, wherein said temperature sensor is an NTC element.

3. Radiant heating device according to claim 1, wherein an operating temperature of said temperature sensor lies between 300 C. and 650 C.

4. Radiant heating device according to claim 1, wherein said temperature sensor is arranged within said outer edge and above said carrier surface.

5. Radiant heating device according to claim 4, wherein said temperature sensor is arranged in an outer region of said carrier surface.

6. Radiant heating device according to claim 5, wherein said temperature sensor is arranged at a point of between 80% and 60% of the shortest distance between a centre point of said carrier surface and said outer edge at a distance from said centre point.

7. Radiant heating device according to claim 1, wherein said temperature sensor housing lies directly on said carrier surface and is fastened in an interlocking manner or by adhesive bonding.

8. Radiant heating device according to claim 1, wherein said temperature sensor housing is open at a bottom in a direction to said carrier surface.

9. Radiant heating device according to claim 1, wherein said temperature sensor housing has a thermally insulating insulation housing part, said thermally insulating insulation housing part consisting of thermally insulating material.

10. Radiant heating device according to claim 1, wherein said temperature sensor housing has an electrically insulating insulation housing part, said electrically insulating insulation housing part consisting of electrically insulating material.

11. Radiant heating device according to claim 9, wherein the said thermally insulating insulation housing part and said electrically insulating insulation housing part are designed and arranged at least partially as a double-layer material arrangement and at least partially form said temperature sensor housing.

12. Radiant heating device according to claim 11, wherein said temperature sensor is arranged completely within said electrically insulating insulation housing part, and at least 80% of said electrically insulation housing part is arranged in the thermally insulating insulation housing part.

13. Radiant heating device according to claim 12, wherein said electrically insulating insulation housing part is arranged on a top side of said thermally insulating insulation housing part.

14. Radiant heating device according to claim 13, wherein said electrically insulating insulation housing part is arranged on said top side of said thermally insulating insulation housing part or in a manner protruding out of said top side with an excess length over said top side beyond said thermally insulating insulation housing part of between 0.1 mm and 3 mm.

15. Radiant heating device according to claim 11, wherein said thermally insulating insulation housing part has an opening at a top side, and said electrically insulating insulation housing part is inserted into said opening by way of a surface region protruding laterally in a collar-like manner and resting on said top side of said thermally insulating insulation housing part.

16. Radiant heating device according to claim 15, wherein said opening passes through said thermally insulating insulation housing part to a bottom of said thermally insulating insulation housing part for electrical connection of said temperature sensor from below.

17. Radiant heating device according to claim 16, wherein said electrical connection of said temperature sensor passes through said carrier and said carrier surface.

18. Radiant heating device according to claim 10, wherein said temperature sensor is encapsulated or completely enclosed in said electrically insulating insulation housing part.

19. Radiant heating device according to claim 10, wherein said electrically insulating insulation housing part has a wall thickness of at most 3 mm.

20. Radiant heating device according to claim 9, wherein said thermally insulating insulation housing part has a wall thickness of at most 10 mm, wherein a maximum thickness of said wall of said thermally insulating insulation housing part is provided to a lateral side.

21. Radiant heating device according to claim 1, wherein said temperature sensor housing is arranged high on said radiant heating device in such a way that it lies, by way of said top side, at a height of +/0.5 mm to +/2 mm of a highest plane of said radiant heating device or of said top side of said outer edge.

22. Hob comprising at least one radiant heating device according to claim 1, wherein said hob has a hob plate with a bottom side, wherein said radiant heating device is pressed against said bottom side from below, wherein said temperature sensor or a temperature sensor housing are at a distance of at most 2 mm from said bottom side of said hob plate.

23. Hob according to claim 22, wherein it has a plurality of said radiant heating devices, wherein at least one said radiant heating device is not designed according to claim 1, but has a temperature sensor of different design than said temperature sensor of said radiant heating device according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further advantages and aspects of the invention can be found in the claims and the following description of preferred exemplary embodiments of the invention which are explained below with reference to the figures, in which:

[0031] FIG. 1 shows a sectional illustration through a hob according to the invention comprising a radiant heating device according to the invention having a temperature sensor in a temperature sensor housing,

[0032] FIG. 2 shows a temperature sensor housing in accordance with FIG. 1 in views from above, from the side and from the front,

[0033] FIG. 3 shows a plan view of the radiant heating device according to the invention similarly to FIG. 1,

[0034] FIG. 4 shows an oblique illustration of the radiant heating device from FIG. 3, and

[0035] FIG. 5 shows a plan view of a modified radiant heating device which is designed as a so-called two-circuit radiant heating device having a single temperature sensor.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0036] FIG. 1 shows a highly enlarged lateral sectional illustration of a hob 11 according to the invention. The hob 11 has a hob plate 12 which advantageously consists of glass ceramic as is customary. The hob plate 12 has a top side 13 and a bottom side 14. A cooking point 16 is formed on the top side 13. A pot 18 is placed on the said cooking point, a detail of the bottom of which pot is illustrated.

[0037] A radiant heating device 20 according to the invention, only a detail of which is illustrated here, is arranged below the hob plate 12. However, the said radiant heating device is designed substantially according to FIGS. 3 and 4. The radiant heating device 20 has a carrier tray 22 composed of sheet metal, as is customary, that is to say with a vertically raised encircling edge. A carrier 23 composed of special thermally insulating and high-temperature-resistant and stable material is laid into the carrier tray 22. Reference is made to U.S. Pat. No. 5,834,740 in this respect. The carrier 23 has a top side 24. An insulating edge 25, illustrated in FIGS. 3 and 4, which is placed onto the top side and, by way of its top side, can and should be pressed against the bottom side 14 of the hob plate 12 runs along an outer edge. The carrier 23 has a continuous bore 26 which also passes through the carrier tray 22. This will be explained in yet further detail below.

[0038] A temperature sensor housing 30 having a temperature sensor 40 arranged therein is placed, possibly adhesively bonded, onto the carrier 23 in a free region 29 in which no heating elements 27 run on the carrier 23. The said temperature sensor housing can have the abovementioned dimensions. The temperature sensor housing 30 is of two-part design. A first part, which forms the outer side, is formed by an insulation housing part 32, advantageously produced from expanded and pressed vermiculite. The said first part is highly temperature-resistant, and at the same time has very good thermal insulating properties. The insulation housing part 32 has, on the relatively long lateral side, two oblique sides 33, that is to say becomes narrower from top to bottom. A top side 34 of the insulation housing part 32 is largely flat. An opening 36, here advantageously designed as a round-cylindrical opening 36, passes through the insulation housing part 32. The said opening should be in alignment with the bore 26 in the carrier 23 in the fastened state.

[0039] An insulation housing part 38 is inserted into the said opening 36 from above. A lower insulation housing part 38a can be designed as a kind of short round pipe and consist of ceramic, advantageously a solid and highly temperature-stable ceramic. The insulation housing part 38a can be designed as a round-cylindrical pipe with a wall thickness of less than 1.5 mm, advantageously barely 1 mm. A further insulation housing part 38b is mounted on top. The said further insulation housing part is a round disc which is produced and connected in one piece with the insulation housing part 38a, as an alternative they can be adhesively bonded. Therefore, the upper disc-like insulation housing part 38b acts as a kind of flange. This flange or the insulation housing part 38b bears on the top side 34 of the insulation housing part 32. A wall thickness of the upper insulation housing part 38b also advantageously lies in the abovementioned region, so that the same wall thickness of both insulation housing parts is produced overall. The pipe-like insulation housing part 32a fits precisely into the opening 36 and may possibly be jammed therein to a certain extent in the process.

[0040] The temperature sensor 40, advantageously designed as an above-described NTC sensor, bears against the disc-like insulation housing part 38b, advantageously directly against the bottom side of the said insulation housing part, within the insulation housing part at the top. Therefore, good temperature transfer or heat transfer is ensured here. Furthermore, the temperature sensor 40 is potted or fastened by means of a potting compound 43 and defined in respect of its position. Therefore, the temperature sensor 40 is also protected mechanically and against corrosion. Furthermore, it is possible to ensure in this way that the said temperature sensor also actually bears permanently against the bottom side of the upper insulation housing part 38b for heat transfer which is as good and direct as possible.

[0041] By way of being placed against the bottom side of the upper insulation housing part 38b and on account of its low wall thickness, the temperature sensor 40 can detect a temperature above it, that is to say on the insulation housing part 38b, relatively accurately and primarily very quickly. The said temperature can be the temperature of the hob plate 12 in the region above the said temperature sensor. On account of the relatively poor thermal conductivity of glass ceramic, in particular poor lateral thermal conductivity, temperature influences of the heating elements 27 of the radiant heating device 20 are low or negligible. Similarly, influencing of the temperature of the hob plate 12 directly above the temperature sensor 40 is only very low, a temperature detection through the hob plate 12, which is a few millimetres thick, at the top, that is to say in the direction of the pot 18 or its bottom, is more direct and predominant. Therefore, the temperature sensor 40 can very readily identify the temperature of a pot 18 which is placed above the said temperature sensor on the cooking point 16 which is formed by the radiant heating device 20. Owing to the thermal insulation of the relatively thick insulation housing part 32, an influence of the heating elements 27 arranged laterally beneath the said insulation housing part is relatively minor. The temperature sensor 40 therefore measures, in simple terms, a temperature of the hob plate 12 and a pot 18 which is placed above it much more strongly or predominantly than that of the heating elements 27 themselves.

[0042] Owing to the relatively complicated two-part or two-piece refinement of the temperature sensor housing 30 composed of the two different materials, very good thermal insulation of the temperature sensor can be achieved to the side, the material vermiculite or phyllosilicate being very well suited to this. Owing to the arrangement of the temperature sensor itself in the thin insulation housing part composed of relatively good thermally insulating ceramic, heat transfer at the top, that is to say in the direction of the hob plate, can be very good.

[0043] The various views of the temperature sensor housing 30 in accordance with FIG. 2 show that the oblique sides 33 are provided only on the relatively long lateral sides. The said oblique sides are intended to allow the temperature sensor housing 30 to also be placed in a relatively narrow free region 29 in accordance with FIGS. 3 and 4, without a free region 29 of this kind having to be made bigger. This means, specifically, considerable tool costs and expenditure on conversion. However, in FIGS. 3 and 4, the heating elements 27 come very close to the temperature sensor housing 30 and almost touch it. Although the upper region projects beyond the nearest heating elements 27 on account of the oblique position of the oblique sides, the temperature sensor 40 contained therein and positioned centrally therebetween does not. The connection wires 41 of the temperature sensor 40 protrude out of the temperature sensor housing 30 at the bottom. The said connection wires are guided through the bore 26 in the carrier 23 and a corresponding opening therebeneath in the carrier tray 22 and are connected to a controller, not illustrated, of the hob 11, which controller can evaluate the temperature sensor 40.

[0044] It can be seen in FIG. 1 that the upper insulation housing part 38b rests fully on the top side 34 of the insulation housing part 32. Here, a corresponding recess could also be arranged in this top side 34, so that the upper insulation housing part 38b can be arranged in a manner at least partially recessed into this top side 34. However, it should be ensured that the top side of the insulation housing part 38b bears against the bottom side 14 of the hob plate 12 and projects beyond the top side of the insulation housing part 32.

[0045] A manner of laying the heating elements 27 which is known per se can be seen in the illustrations of FIGS. 3 and 4 of a radiant heating device 20 according to the invention. The said heating elements are electrically connected to a connection part 28. A free region 29 extends on the inside from this connection part 28 to a central region of the carrier 23. Here, elongate thermomechanical temperature pickups, so-called bar-type controllers, can also run as far as this central region. However, in the exemplary embodiment illustrated here, a bar-type controller of this kind is dispensed with, the temperature sensor 40 in the temperature sensor housing 30 is the only one in the entire radiant heating device 20. The said temperature sensor performs all the functions of the said elongate thermomechanical temperature pickup. Neither mechanical temperature sensors nor temperature sensors which can be electrically or electronically evaluated are additionally present here in the radiant heating device 20 according to the invention. This reduces the expenditure on evaluation and the material costs and assembly costs.

[0046] FIG. 3 shows that the temperature sensor 40 which is arranged below the upper insulation housing part 38b is arranged relatively far outside on or above a carrier surface of the carrier 23, that is to say close to the insulating edge 25. With respect to the outermost turn of the heating element 27, this is approximately 75% of the distance between the centre point of the carrier 23 and the inner side of the insulating edge 25. In this outer region, it can be assumed that a cooking vessel or a pot 18 which is placed down rests directly on the top side 13 of the hob plate 12. Owing to the said cooking vessel or pot resting directly on the hob plate 12 composed of glass ceramic, the temperature sensor 40 can detect the temperature of the said pot 18 through the upper insulation housing part 38b and through the hob plate 12 by means of contact heat.

[0047] If the temperature of the pot 18 increases to a great extent or reaches a temperature of above 350 C. or close to 385 C., starting from which intense development of smoke can occur when oil is heated or the oil can also catch fire, the temperature sensor 40 or the connected controller should identify this critical temperature, possibly using correction values or compensation values. The controller should then reduce the heating power of the radiant heating device 20, possibly even switch off the said radiant heating device.

[0048] It can be seen in the oblique illustration of FIG. 4 how, on account of the temperature sensor 30 being of narrower design towards the bottom on account of the oblique sides 33, the one heating element can run past the connection part 28 very close to it. Therefore, although it may run below the projection of the top side 34 of the insulation housing part 32, it is still not below the temperature sensor 40 itself, as is shown looking at FIG. 3 together with FIG. 1.

[0049] FIG. 5 shows a modification of the invention with a radiant heating device 120 which is designed as a so-called two-circuit heater. An inner round region has inner heating elements 127a which can be laid in a pattern in accordance with FIG. 3, as is indicated. Heating elements 127b are laid so as to run in a flat manner, specifically once again in a meandering manner, in an outer heating circuit which surrounds the inner heating circuit in an annular manner. The heating elements 127a and 127b are all connected to the connection part 128 or guided on the said connection part. From there, connection is made with an electrical power supply, for example via relays. The switching is performed by the controller.

[0050] This radiant heating device 120 also has a single temperature sensor, specifically integrated into the temperature sensor housing 130 in accordance with the refinement of FIGS. 1 to 4. This temperature sensor housing 130 also has an insulation housing part 132 with an opening from the top. An insulation housing part is inserted into the said insulation housing part, the upper disc-like insulation housing part 138b, in which the temperature sensor is arranged in a potted manner in turn, is illustrated. The electrical connection of the said insulation housing part is advantageously at the bottom through the carrier 123 and through the carrier tray 122, as described above.

[0051] In comparison to the arrangement of the temperature sensor in FIG. 3, it can be seen that the temperature sensor sits radially further to the outside here in FIG. 5 than in FIG. 3, and this can be identified on the insulation housing part 138b. The said temperature sensor sits, as it were, just in front of the inner insulating edge 125a. Therefore, the said temperature sensor lies at most close to the edge region of the outer second heating circuit with the heating elements 127b.

[0052] If a small pot corresponding to the inner heating circuit is placed onto the associated cooking point, the size of which corresponds to the inner insulating edge 125a illustrated in dashed lines for example, the said pot can be heated by the heating elements 127a. These form a free region 129 in which the temperature sensor housing 130 is mounted. It can be clearly seen here that the free region is wider than in FIG. 3, that is to say the distance from the temperature sensor housing 130 is greater.

[0053] Here, the temperature sensor is arranged at approximately 90% of the distance between the centre point of the carrier 123 and the inner insulating edge 125a. Therefore, a small pot will rest on the top side of a hob plate with the resulting very advantageous direct and rapid temperature measurement as explained above in this case too.

[0054] If a large pot corresponding to the size of the profile of the outer insulating edge 125b illustrated in dashed lines is placed onto the cooking point of the radiant heating device 120, it presumably also lies fully on the top side of the hob plate in the radially outer region. This then also still applies for that region of the pot which is located above the temperature sensor, so that the said temperature sensor can once again precisely and rapidly detect the pot temperature.

[0055] Therefore, a heating device 120 of this kind, corresponding to FIG. 5, can also be provided as a so-called two-circuit heating device with a single temperature sensor according to the invention, and further temperature sensors or temperature pickups are not required. Owing to the possible precise evaluation of the temperature sensor, an excessively high temperature of the hob plate, usually consisting of glass ceramic, can be identified and as a result even avoided. A dangerous temperature of this kind lies at 600 C. to 650 C. Furthermore, a temperature of a pot which is placed above the said temperature sensor can be detected very rapidly, so that the said pot also does not become hotter than intended or allowed.