GB2229615A

GB2229615A - Radiant heating device

Info

Publication number: GB2229615A
Application number: GB9005950A
Authority: GB
Inventors: Berndt Gierer
Original assignee: AKO Werke GmbH and Co KG
Current assignee: AKO Werke GmbH and Co KG
Priority date: 1989-03-16
Filing date: 1990-03-16
Publication date: 1990-09-26
Also published as: DE3908599A1; GB9005950D0

Description

1 1 Radiant heating device The invention relates to a radiant heating

device of a cooker, which has two separate heaters in at least one insulating- support disposed under a flat hob, in particular a glass ceramics hob, the first heater being installed on a first partial face of the insulating support, having a first circular outer diameter, and the second heater being installed on a second partial face having a second circular outer diameter, the second outer diameter being larger than the first outer diameter and the first partial face lying inside the second partial face.

A radiant heating device of this kind is known from DE-OS 31 02 919 and in DE-GM 81 33 341. Such dual circle heaters have the DurDose of adapting the heat-effective diameter of one and the same hot plate of the hob to cooking utensils of different base diameters. When a cooking utensil having a relatively small base diameter is used, only the heater of the inner partial face is switched on. When a cooking utensil of relatively large base diameter is used, the heater of the outer partial face is also switched on. Since a series of cooking utensils of different base diameters is usually available for cooking, the dual circle heater makes it possible for cooking utensils with different base diameters to be used on the same, circular hot plate, 4ithout the cooking utensils either projecting a long way over the hot plate, which delays the cooking process, or the cooking area projecting beyond the cooking utensil, which means wasted energy. The dual circle heater for cooking utensils with a circular base diameter has the further advantage that, when cooking utensils of different base' diameters are used, there is no need to move to other hot plates on the hob for the sake of rapid and economical heating.

2 AccordIng to the prior art, in radiant heating devices for coolil-.ix-ig utensils with a circular base diameter, the two partial faces carrying the heaters are always arranged concentrically. This arrangement is obvious, because it assumes that a cooking utensil with a circular base diameter is always placed in the centre of the hot plate whatever the size of the diameter.

However, it has been found that the concentric arrangement of the two heaters or the Partial faces carrying them is disadvantageous, for when a cooking utensil of small base diameter is placed on the cooker, there is an area around the cooking utensil on the hob which is unusable. Furthermore, any handle projecting radially from a cooking utensil of small- base diameter becomes hot if: for some reason the outer heater is also switched on or has recently been on.

DE-AS 26 53 389 discloses a cooking hob with a plurality of s-oaced. circular hot plates. Between every two hot plates an addit-ional hot Plate is nrrovided. With th-1s arrangement, oval cooking utensils can also be heated. In DE-OS 30 04 187, a semi-circular heating surface is disposed next. to a circular heating surface. This means that, in addition to a cookIng utensil with a certain circular diameter, an oval cooking utensil can also be heated. DE-PS 29 43 477 shows a circular heating surface, in which two additional heaters are provided opposite one another. In this case, in addition to a cooking utensil with a circular base, oval cooking utensils of different lengths may also be heated. In these devices, it is not possible to heat cooking utensils of different circular base diameters quickly and economically, since in cases where the circular heater is provided for a cooking utensil with a small base diameter, a cooking utensil with a relatively large base diameter projects over the heating area. on the other hand, if the circular heater is provided for a cooking utensil of 4 -1 "% r, r '. C ' '. (11.

1 3 i relatively large base diameter, when a cooking utensil of relatively small- base diameter is used, energy is wasted.

The object of the invention is to provide a device of the kind mentioned at the beginning i: or use with cooking utensils of different circular base diameters, which forms a cooking area on the hob, whereon a cooking utensil with a relatively small circular base diameter can be placed as close to the periphery as possible and can thus be heated by the first heater as economically and quickly as possible, and on which nevertheless a cooking utensil with a relatively large circular be can also be heated economically and quickly.

According to the invention, the above object is achieved in a device of the kind mentioned at the beginning by arranging [_he first Dartl'a! face eccentric to the second partial face and by making thesumofthe distance between thecentre points 0.0 the two outer d-Lame.'L..ers and of the radius of the smaller, first outer diameter substantially equal to the radius of 1-he larger second outer diameter.

if a cooking utens--11 of large circular base diameter is used which corresponds to the second outer diameter, the cooking utensil then stands fully under the influence of the first and second heaters, the first heater ly-Ing eccentrically below the cooking utensil, but not projecting beyond it. If a cooking utensils of relatively small base diameter, corresponding to the first outer diameter, is used, this stands eccentrically on the cooking area above the first heater. Even if the second heater is additionally switched on, the handle of the cooking utensil simply has to be oriented so that it is not heated by the heat from the second heater. Due to the eccentricity, there is a place on t he cooking area next to the cooking utensil of relatively small base diameter, over the second heater which can be used to heat another cooking utensil, without the handle of 4 1 the cooking utensil standing over the f irst heater being heated. The possibility of placing the cooking utensi' of relatively small base diameter eccentrically ensures its quick and economical heating, together with the possibility of unhindered access and of using the remaining surface of the heating area, and yet the possibility of heating a cooking utensil of relatively large base diameter quickly and economically is not impaired.

A further advantage is that a conventionally provided rodshaped sensor of a thermostat, which must be screened from the effect of the second heater, in this case needs no sDecial formation. This temperature sensor can be so mounted above the first heater that it does not extend over ithe second heater. Thus measures to comDensa-Le for the effect of- the second heater on the temDerature sensor are su-oerfluous. The thermostat therefore has the same sw itching behavlour irrespectively of xq-.riet., ier the second heater is on or off.

The invention also ensures that ---n-e two heaters can be installed simultaneously, as the two installation heads, each of which installs one of the heaters, do not interfere with the path of movement and the heaters do not cross over or under one another. This accelerates Droduction.

In a preferred embodiment of the invention, the distance of the one partial face from the under-side of the hob is smaller than the distance of the other partial face from the under-side of the hob. Thus the one heater lies closer to the hob than the other heater. The radiation heat from the heater nearer to the hob thus spreads less far into the area of the hob lying above the other heater than would be the case if the heater had a relatively large distance from the hob. The lower heater also spreads heat less far into the region above the higher heater, since the step between the two partial faces prevents this. Thus quick and economical heating is improved, because each heater substantially only radiates hea.; L-. to the area of the hob 'Lying above itself. At the same time, the existence of an unheated zone in the border region between the two heaters on the cooking area of the hob is avoided.

Further advantageous embodiments of the invention-will appear from the subclaims and the following description. The drawing shows:

Fig. 1 a plan view of a radiant heating device in diagrammatic form, F.

ig. 2 a sec-L-o.-,i through the radiant heating device under a hob, along the line I!-II according to Fig. 1 and Fig. 3 an alternative embodiment viewed as in Fig. 2.

At least one d.i'.s.i,.-shamed insulating support (2) is mounted under a glass ceramics hob (1). '.-his support (2) has a circular annular edge (3), which faces the hob (1).

A firs;-_ partial face (4) is formed on th.e -i.risula-ting support (2). This has a circular outer diameter (A). A second partial face (5) is also provided on the insulating support (2) and has a circular outer diameter (B). The outer diameter (B) is larger than It-he outer diameter (A). The first partial face (4) lies inside the second partial face (5). The first partial face (4) is arranged eccentrically to the second partial face (5). The centre points (M, N) oil the outer diameter (A, B) are therefore spaced from one another. The distance is marked c. The degree of eccentricity is so chosen that the first partial face (4) extends up to the very outside of the second partial face (5). The sum of the distance (c) of the centre points (M, N) and of the radius (a) of the outer diameter (A) is equal to the radius (b) of the outer diameter (B) (cf. Fig. 2).

6 A first. electric heater (6) is mounted in a spiral form on the first Dartial face (4). A second electric heater (7) is mounted in windings on the second Dart-ial face (5). Each heater (6, 7) is formed by a helical element. The output of the first heater (6) is for example 1 kW, and that of the second heater (7) for example 1.1 kw.

A rod-shaped temperature sensor (8) is so mounted above the first heater (6) or first partial face (4) respectively that it does not cross over the second heater (7). At the point where the outer diameters (A, B) touch one another, the temperature sensor (8) is guided out through the annular edge (3) and. connected to a thermostat (9).

Electrical connections (10, _11) of th.e heater (6) are guided out of 'Llne insullating support (2) where the outer diameter (A) comes close to the outer d-Lame.'L-er (B). T.he connections (10, 11) therefore do not cross the second. heater (7). Electrical connections (12, -13) of Chle second heater (7) are guided out of- the Insulat-ing support (2) next to the connections (10, 11).

The electrical, circuit is so chosen that L-.he heater (6) can be switched on alone and if necessary together with the heater (7). If tChe thermostat (9) responds, both heaters (6, 7) are switched off.

The radiant heating device described is particularly suitable for heating a cooking utensil whose circular base diameter is either equal to diameter (A) or to diameter (B). A cooking utensil with the base diameter (B) is placed concentric to the central point (M) on the cooking area (14) of the hob (1) and heated by both heaters (6, 7). A cooking utensil with the base diameter (A) is placed eccentric to the centre point (M), but concentric to the centre point (N) on the circular cooking area (14). In this case, it is -jw 1 7 standing on the outside of the coo'i,---Lng area (14), so that a handle provided on the cooking utensil can be easily so oriented that it does not stand over the lheater (7). The handle is therefore not heated if for some reason the heater (7) is switched on or has recently been on, so that a certain residual heat can still warm the handle. The heater (7) may for example be switched on in order to heat up or keep warm a smaller cooking utensil placed next to the cooking utensil with the base diameter (A). There is room for this on the cooking area (114) next to the cooking utensil with the base diameter (A).

The partial faces (4, 5) may lie in the same plane so that tine two heaters (6, 7) have the same distance from the hob (1) The partial faces (4, 5) may, however, have different distances from the hob (111) (c.E. Fig. 2, Fig. 3).

According to Fig. 2, the distance between the first partial =ace (4) and the hob (1) is larger than the distance of the second partial face (5) from the hob (1). Accordingly, the heater (6) is lower than the heater (7). The step between th,e two Dartiall faces (4, 5) is indicated by (15). In the example shown, it. is approximately twice as high as the diameter of the helical elements which form the heaters (6, 7).

In the embodiment according to Fig. 3, on the contrary, the distance between the second partial face (5) and the hob (1) is larger than the distance of the first partial face (4) from the hob (1). The embodiment according to Fig. 2 on the other hand has the advantage that there is a very high space above the heater (6) for the temperature sensor (8), so that the structural height of the insulating support (2) can be reduced.

The purpose of stepping the partial faces (4, 5) relative to one another according to Figures 2 and 3 is that the heater a k ( 7) (cf. Fig. 2) or ( 6) (crE. Ficr. J3) cl oser to the hob ( 1) radiates heat less far -'-Into tlhe region of the Inlob (14) lying above the other heater (6 or 7 resDec.';.--Lve'y) than 'f were J. L L- S-Daced further from the _hob (1).

i 2 This stepping further ensures that the lower heater (6) (cf.

Fig. 2) or (7) (cf. Fig. 3) radiates heat less far into the region of the cooking area (14) above the other heater (7 or 6), as the step (15) helps to direct its radiation directly upwards.

A d k 9

Claims

Claims

1_. A radiant heating device for a cooker, which has two separate heaters in at least one insulating support disposed under a flat hob, the first heater being installed on a first partial face of the insulating support, having a first circular outer diameter the second heater -being r and installed on a second partial face having a second circular outer diamter, the second outerdiameter being larger than the first outer diameter and the first partial face lying inside the secondpartial face, wherein the first partial face is disposed eccentric to the second partial face and the sum of the distance between the centre points of the two outer diameters and of the radius of the smaller, firstouter diameter is substantially equal to the radius of the larger second outer diameter.
2. A radiant heating device according to Claim 1, wherein a rod-shaped temperature sensor which extends under the hob, is so guided out through an annular edge of the insulating support that it does not cross the second heater.
3. A radiant heating device according to Claim 2, wherein the temperature sensor is guided out of the insulating support at the point where the first outer diameter and the second outer diameter meet.
4. A radiant heating device according -to Claim 2 or 3, wherein the temperature sensor only extends between the first heater and the hob.
5. A radiant heating device according to any one of the preceding Claims, wherein the first heater is mounted in a spiral form on the first partial face and the second heater is mounted in windings on the second partial face.
6. A radiant heating device according to one of the preceding Claims, wherein connections of the first heater are guided out of the insulating support, without crossing, in the region where the first outer diameter and the second outer diameter approach one another.
7. A radiant heating device according to one of the preceding Claims, wherein the distance of the one partial face from the underside of the hob is smaller than the distance of the other partial face from the underside of the hob.
8. A radiant heating device according to Claim 7, wherein a step is provided between the first partial face and the second partial face.
9. A radiant heating device according to Cla I'm 8, wherein the height of the step is at least the same size as the diameter of the helical element.
10. A radiant heating device according to any one of the preceding Claims, wherein the first and second partial faces abut a circular annular edge of the insulating support in regions where they do not abut one another.
11. A radiant heating device substantially as described herein with reference to the accompanying drawings.

Published 1990 at ThePaTe.-.tO-ffice. State House. 66-1Higl,.Holbc)rr,. LondoriWC1R4TP- Further copesmkv be obtained frorn -,nePc-.ntO!fi-.e Sales Brancl. SI Mary Crky- Orpington. Kent BRS 3RD- Printed by Multiplex techniques ltd. St Mary Crky. Ken,. Con 157