EP0982973A2 - Sensor for cooking vessel detection - Google Patents

Abstract

The sensor is the active part of an inductive oscillation circuit that forms part of a controller and pref. operates with detuning. The sensor is arranged as a fixed shape, self-supporting, temp. resistant loop (30) of electrically conducting material near at least one zone (18,19) heated by the heating element (21). An Independent claim is also included for a radiation heating body.

Description

APPLICATION AREA AND PRIOR ART

The invention relates to a sensor for an electrical Radiant heater to detect the positioning of a Cooking vessel on a hotplate covering the radiator, especially a glass ceramic plate.

The automatic switching on and off of a hotplate in is directly dependent on the installation of a cooking vessel a goal that has been pursued for a long time, but has so far been incomplete, with great technical effort and not with the necessary reliability could be solved, why such systems have not yet been introduced in practice.

The systems proposed for this purpose are based on the different principles, mostly the type and arrangement of the sensor is crucial. So mechanical, capacitive, optical, resistive and inductive sensors proposed. Inductive sensors have coils with proposed several turns as well as with only one turn been. These coils are either circular and concentric arranged or framed to the respective cooking zone this in the case of non-circular shaped cooking zones. Here are these coils usually in the area of edge insulation. (See EP 490 289 B1 and EP 442 275 A2)

The single-winded pot detection loop mentioned is from the DE 37 11 589 A1 has become known. It is about a passive short circuit loop between the heating elements and a glass ceramic plate is arranged. It is from a magnetic field transmitter arranged below the heating elements externally charged. By periodically shorting and one The evaluation circuit becomes the corresponding damping measurement acted upon. The introduction of such a system in the Practice fails because of the great effort and above all the necessary large height to accommodate the magnetic field encoder.

The mentioned multi-wind coils in the outer edge area (or in an unheated central zone) cause thermal problems and are as recognized by the invention and how will be explained later with respect to a sharp signal generation and detection less suitable.

DE 37 33 108 describes a circuit arrangement g for a Pot detection system known with a drip detection sensor who works in the manner of a passive four-pole. The Sensor working according to the type of transmitter and receiver antennas is on the underside of the hotplate as a printed circuit applied and has a generally spiral arrangement.

EP 0 469 189 A describes a control method for the Heating elements of a stove with an air coil with only a few turns of the sensor, about its arrangement and design no details are given.

DE 42 24 934 A describes a sensor arrangement for a Pot detection system has become known, in which two capacitive, electrically conductive, temperature-resistant Pot detection sensors on the outer edge of radiant heaters are arranged. These are discrete sensors, which is only a small area of the circumference of the radiant heater cover up. Their effect and the switch-on behavior is therefore depends to a large extent on where the Sensors are arranged on the circumference. The exact positioning of a cooking vessel can therefore not be recorded without a doubt.

TASK AND SOLUTION

The object of the invention is an active sensor for a To create radiant heaters that are simple and robust structure is easy to arrange on the radiant heater and the most concise signal possible to control the radiator delivers.

This object is solved by claim 1.

The sensor, the part of an inductive, preferably by means of Oscillating circuit detuning working oscillating circuit one Control is, is made of electrically conductive as a loop Material around the heating zone and at least this partially overlapping. This is opposite a rotating sensor in the edge area of the radiator the signal is much more meaningful for the coverage the heating zone and thus more concise for the detection. This is unusual in that one should assume that through a sensor arranged on the edge, the associated cooking vessel size would be recognized particularly precisely because of the signal size in the form of the relative frequency shift in the peripheral area is particularly large and then strong (parabolic) for Falls in the middle. The problem here, however, is that how such an edge coil was hardly found between one relatively small pot that still cause an activation should, and a large, but shifted to the heating surface Pot can distinguish, which do not cause an activation should. In addition, there was always a problem with the edge coils due to the fact that radiant heaters are usually are arranged in a tin plate, the bottom of which and especially its edge strongly dampens the resonant circuit. So the field extends over a very narrow edge area, that delivers an evaluable signal at all.

In general, such radiation heaters must be taken into account be that the bottom of the tin plate a Damping the magnetic field causes so that this only relatively small-scale as a hose around the actual sensor conductor can train around.

By arranging the sensor loop in the area of the heating zone can cover the sensor as much as possible in the Area to be achieved where the pot is switched on should cause, and the least possible coverage in the Area in which the heating element in question is switched off should be. Therefore, even a small saucepan brings with it proper centric arrangement a large signal while a moved pot only one clearly distinguishable from it small signal. So the sensor loop should be hers effective diameter in the range of the minimum diameter have something advantageous about it, namely around the area of Magnetic field "hose". Due to the distance to the outer edge there is no appreciable damping by this, the would fake a pot, so to speak. That’s what it is possible with only one or possibly only a few turns exhibiting sensor loop, while in the past mostly the arrangement of a coil with many turns considered necessary was to generate a sufficiently large signal in the form of a Obtain frequency shift in the measuring resonant circuit.

The invention therefore advantageously enables the sensor loop in the immediate area of the heating zone, i.e. right away to be exposed to the radiant heat because at such a coil with one or only small turns Air gap between them, insulation is not necessary. she consists of a stable, self-supporting and temperature-resistant Conducting material, preferably from a tube or solid, strong wire. A material comes as a material like a high-alloy steel, e.g. a FeCrNi alloy in question. Formation from non-ferromagnetic material is useful because with a ferromagnetic Material due to the occurring high temperature of the Curie point would be exceeded and that at that point changing magnetic properties to a signal would lead that from the desired determination of a Cooking vessel position is completely independent and therefore the result would falsify.

The sensor loop and the controller can be advantageous for Cooking vessel size detection. To this end the sensor loop can be at a radial distance from one another have different effective areas, e.g. in different Circumferential areas essentially in the circumferential direction running loop sections through radial connecting sections are interconnected. It can for example a sensor loop with a circular or Polygonal shape with omega-shaped bulges result. This Clover leaf shape has been recognized as particularly effective.

Since the signal size in essentially the degree of coverage of the sensor loop corresponds to a cooking vessel has the characteristic "Frequency deviation / diametrical coverage through the cooking vessel" in the Contrary to the parabolic course a stepped course with a more steep shifted to the inside of the heating zone Section that has two diameters for two-circuit radiators may have. In this way, the waveform can be stronger be adapted to the ideal shape. This would be with the radiator with only one heating zone, a flat signal curve in the edge area, the steepest possible drop in the area of the diameter of the smallest possible pot that still has to be switched on should lead, and then a flat, as deep as possible Course up to the middle of the heating zone.

In the case of a two-circuit radiator, in which, depending on the size of the cooking vessel either only one (medium) or Both heating zones can be switched on by the form of only one sensor having two effective ranges a very concise signal curve achieved with two approximate levels to a differentiated engagement of the two Heating zones can be evaluated.

The robust, self-supporting sensor loop can be used with any Radiator configurations can be easily arranged. This usually have an outer edge made of insulating material and for dual-circuit radiators if necessary, a partition. On this the Sensor loop rest, for which recesses are provided can be a system of sensor and insulating edge on the Plate or a certain distance, but only a short distance from it to manufacture. Even with existing radiator designs is a retrofit with a pot detection possible.

It has been shown that by the shape, type and arrangement the sensor loop that with previous sensors of this type very bad signal / noise ratio significantly improved can be.

These and other features go beyond the claims also from the description and the drawings, wherein the individual features individually or separately several in the form of sub-combinations in one embodiment of the invention and in other fields be and advantageous as well as protective designs can represent, for which protection is claimed here. The division of the application into individual sections as well Inter-headings limit those made under them Statements are not generally applicable.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1

einen zentralen Schnitt durch einen Strahlungsheizkörper unter einer Glaskeramikplatte mit angedeuteten Kochgefäßen,

Fig. 2

eine Draufsicht auf den Strahlungsheizkörper nach Fig. 1,

Fig. 3

eine Diagramm über den Frequenzgang bei einem Zweikreisheizkörper,

Fig. 4

eine Draufsicht auf eine Variante eines Strahlungsheizkörpers,

Fig. 5-10

Draufsichten auf weitere Varianten in schematischer Darstellung und

Fig. 11

eine Frequenzgang-Diagramm eines Sensors für einen Einkreisheizkörper (Fig. 5 bis 7).

An embodiment of the invention is shown in the drawings and is explained in more detail below. The drawings show:

Fig. 1

a central section through a radiant heater under a glass ceramic plate with indicated cooking vessels,

Fig. 2

2 shows a top view of the radiant heater according to FIG. 1,

Fig. 3

a diagram of the frequency response in a two-circuit radiator,

Fig. 4

a plan view of a variant of a radiant heater,

Fig. 5-10

Top views of further variants in a schematic representation and

Fig. 11

a frequency response diagram of a sensor for a single-circuit radiator (Fig. 5 to 7).

DESCRIPTION OF THE EMBODIMENTS

1 and 2 show an electric radiant heater 11, the under a glass ceramic plate 12 an electrical Cooktop or another radiation cooker arranged is. It has a flat tin plate 13, the Bottom 14 and edge 15 a bottom layer 16 and an edge 17 made of electrically and thermally insulating and insulating Take up heat-resistant insulating material. It is about preferably a microporous bulk material pressed fumed silica airgel. The outer edge 17 is manufactured separately due to improved mechanical strength and consists of a pressed or wet formed and then post-dried ceramic fiber with binders etc.

The edge of the sheet 15 does not quite reach the glass ceramic plate 12 approach, but probably the insulating edge 17, the bottom is pressed onto the glass ceramic plate by the radiator 11 pressed up by a pressure spring, not shown is.

The radiant heater has two concentric to each other Heating zones 18, 19 on each other through an intermediate wall 20 are delimited, but not to the glass ceramic plate reaches.

Electrical heating elements 21 are located in both heating zones 18, 19 arranged in the form of thin, wavy ribbons, which stand upright on the surface 22 of the insulating body 16 are arranged upright and in this with her bottom molded feet are anchored, which as a result the corrugation of the tape has a spade shape. You cover the two heating zones 18, 19 evenly with the exception an unheated central zone 59, in which an upward Projection 43 of the insulating base 16 lies.

Fig. 2 shows the arrangement of the heating elements in a meandering shape Ring tracks. They are connected via heating element connections 23 a temperature monitor 24 and a separate terminal block 25 switched so that the outer heating zone 19 at Operation of the radiator heating zone 18 always on can optionally be switched on. The temperature monitor 24 has a rod-shaped sensor 26 which is connected to a temperature monitor / contact to maintain a permissible maximum temperature on the underside of the glass ceramic and a hot detector contact to signal the hot state of the Radiator acts in a temperature monitor head 27. The Sensor 26 protrudes through the edge 17 of the insulating body and through the Partition 20 through and runs in a plane above of heating elements 21, but mostly in one of heating elements free alley 28.

The heater has a sensor in the form of a loop 30 on, the part of a controller 31 for detecting the positioning a cooking vessel on top of the radiator Hotplate 12 is. The sensor loop 30 forms one Inductance of a resonant circuit 32 with a relative high frequency of 1 MHz to 5 MHz, for example is. The damping changes when a cooking vessel is placed on it the sensor loop 30 and thus the frequency of the Oscillating circuit 32. This is evaluated in the controller 31 and depending on it, mechanical or electronic Controlled switches 33, 33a in the controller that the Switch on heating zones 18, 19 for operation.

To set the respective released service is also an energy control device 34 (often also as an energy regulator designated) provided, which has an adjustment knob 35 a certain power can be set. It can also a temperature controller may be provided. When regulating or Control is mostly a cyclical power release, i.e. a suspension regulation or control. The Energy control device 34 can be thermo-mechanical, i.e. as Bimetal switch or, preferably, as an electronic component be formed, which may also be integrated into the controller 31 can be. In order to avoid interference from the resonant circuit 32 to keep away, the line between the actual Sensor loop 30 and the other elements of the Resonant circuit should be kept as short as possible. Also one Shielding of the lines is possible. Possibly. could that actual cooking vessel detection contained component 36 of Control also separate from the rest of the radiator controls arranged spatially close to the radiant heater 11 his.

The sensor loop 30 consists of a relatively thick one Round wire with a diameter between 1 and 4 millimeters, preferably about 2 millimeters, from a heat resistant and non-magnetizable material. For example a high-alloy steel like an iron-chromium-nickel alloy his. Suitable materials are e.g. a steel with material no. 1.4876 or a heating conductor material with the material no. 2.4869.

The sensor can be grounded on one side. To achieve a low earth resistance (preferably less than 0.1 ohm), and the very low required for this ohmic resistance of the sensor, this can be corresponding run thick. For its function as a pot detection sensor with high frequency exposure is due the skin effect only their surface effective so that they could also be designed as a tube. Because of the small ohmic resistance this could then also with copper or another highly conductive material while the jacket material for temperature resistance and scale resistance worries. An embodiment is particularly advantageous with an electrically highly conductive galvanic coating, e.g. made of silver, or a version made of highly conductive solid material with e.g. galvanic, scale-resistant coating. The very rigid design of the sensor loop 30 ensures that that even with high thermal loads not with a drop on the heating elements 21 is to be expected.

Because of the shape of the sensor loop 30, reference is made to the drawings Referred. In Fig. 2 the sensor loop forms a single wind Coil with over the outer heating zone 19, but with relatively large radial distance from the outer edge 17 outer peripheral portions 37 and, again with a radial distance from the intermediate wall 20, extending over the heating zone 18 inner peripheral portions 38.

These circumferential sections are circular arc sections in FIG. 2 of different diameters by connecting sections 39 are connected. These connecting sections run essentially radially, but in this way oblique that the sum of the angles of the outer and inner peripheral portions 37, 38 is greater than 360 °. The top view on the sensor loop 30 has the basic shape of a three-leaf Shamrock with a relatively large, almost a full circle forming central area and three lateral "leaves" in Triangular sector or omega shape. Depending on the size and Control engineering requirements can also include more circumferential section sectors be provided. On one of the peripheral section sectors 40 are connections 41 in the form of externally directed, mutually parallel sections of the Loop material provided.

The entire sensor loop 30 is of the shape described flat and self-supporting due to the relatively strong material and dimensionally stable. It lies in the present example on the one hand in the area of the connections 41 in shallow depressions the outer edge of the insulating body 17 and is based in rest with their connecting sections 39 on the partition 20 from which does not quite reach the glass ceramic plate. As a result, the sensor loop is attached or with short distance from the underside of the glass ceramic plate 12 arranged and with a safety distance above the Heating elements 21. It can be seen that the sensor 26 of the Temperature monitor due to the arrangement shown Crosses the sensor loop only once, in the area an inner peripheral portion 38. Runs in this area he also in alley 28, so that he could risk a collision be placed somewhat lower with the heating elements 21 could. It is also possible to open one of the connections 41 lead out one side of the temperature sensor 26 so that every crossing sensor / loop is avoided. Feeler and The loop can then lie in the same plane. This will the space 42 determining the overall height of the radiant heater between the base 16 supporting the heating elements 21 and the Glass ceramic plate 12 ideally used and the distances for the High voltage testing can be followed.

2 a two-circuit radiator with two concentric Heating zones 18, 19 shows, in Fig. 4 is a two-circuit heater shown with an overall elongated oval shape. This radiant heater 11 has the same for the rest Basic structure of a circular main heating zone 18 to which one side, delimited by a partition 20, an additional heating zone 19 connects, which is a half or quarter moon-shaped Has shape. A temperature monitor 24 is inclined provided on the main heating zone 18 and its sensor 26 protrudes radial only about to the middle, where it is on a middle Projection 43 in the unheated middle zone 59 of the insulating body bottom 16 rests.

The sensor loop provided for this radiant heater 30 is made of the same material as that according to the Figures 1 and 2. It has the shape of a quadrilateral that consists of rectilinear circumferential sections that exist in the area of Longitudinal center line 44 of the radiator led out in parallel Form connections 41. The in the area of the transverse center line 45 the main heating zone 18 lying corners 46 of the square in corresponding shallow depressions 47 of the outer edge of the insulating body 17, but within the edge of the sheet metal shell 15. The peripheral sections 38 thus run in the form of chords with a clear distance from the outer edge over large areas of the radiator and therefore have one effective diameter lying in the area of the heating zone 18.

In the area of the intersection of the longitudinal center line 44 with the Partition 20, i.e. on the opposite of the connections Corner of the square is behind with a strong bend outside a connection section 39 connected to the to outer corners 48, which, like the corners 46, on the Insulating body outer edge 17 in corresponding recesses lie on. You are by an in the embodiment straight section 37a joined together, which is essentially central to the additional heating zone 19, it crosses and crossways runs to the longitudinal center line 44. This section could also rounded according to the crescent shape of the additional heating zone 19 his. The sensor loop 30 is therefore in total seven places on the insulating body, namely at the Corners 46 and 48, at the connections 41 and, with their inner corners 49 between the square legs 38a and the connecting sections 39, on the intermediate wall 20. Your basic shape is about that of a stylized fish.

Of the sensor loop shapes shown schematically in FIGS. 5 to 10 corresponds approximately to that of FIG Fig. 2, but with straight peripheral portions 37, 38 instead the arcuate embodiment shown in Fig. 2. Also are here the peripheral portions 39 largely radially directed and not as retrospective as in Fig. 2. This embodiment has one because of the deviation from the theoretical Ideal shape of the circle (or the pot shape) slightly smaller Characterization of the signal levels as Fig. 2, however, is simpler to manufacture.

The designs according to FIGS. 5 to 7 are for single-circuit radiators thought, i.e. Radiators that are just a contiguous and always have jointly operated heating zone 18. The sensor loop 30 in FIG. 5 has the shape of a square with corners 46 supported on the edge 17. The sensor 46 of the Temperature monitor 24 extends substantially diagonally over that field delimited by the sensor.

6 shows an embodiment corresponding to FIG. 5, in which, however, the sensor 26 of the temperature monitor 24 closes both sides of straight portions of the sensor loop 30 is flanked. Behind the free end of the temperature sensor 26 these are interconnected. This makes it possible the temperature sensor and the sensor loop in the same Level, which leads to the reduction of the overall height with sufficient electrical distances.

7 shows a particularly preferred embodiment of the sensor loop 30, the, running at a distance from the edge 17, almost a circumferential portion 37 forming a full circle, which only through the connections led out parallel to each other 41 and cat-shaped outward facing Corners 46a are interrupted for the necessary circulation worry on the outer edge 17.

8 shows a sensor loop 30 for a two-circuit heating element, in the area of the partition 20 between the main heating zone 18 and the additional heating zone 19 surrounding it. The essentially square design similar to FIG. 5 of the Bow is much smaller and is enough with the outside corners in the area of the auxiliary heating zone, while the peripheral sections 38a paint over the exterior of the main heating zone 18.

10 shows an embodiment for a two-circuit radiator, which, unlike the other radiators, is essentially consisted of a single wind loop, a double loop forms, but which is connected in parallel. Form is that of two squares, one inside the other, both on the same connections 41 are connected and only to increase their surface coverage at a distance from each other have circumferential sections extending, but electrically each form a single wind loop. The inside of the both loops, as described in Fig. 8, on the Partition 20 on, while the outer loop accordingly Fig. 5 rests with its corners on the outer edge 80. The Relative, but elastic design of the sensor loop it also enables e.g. by snapping in Securely define recesses of the edge. Also a fix by inserting it into the insulating material, e.g. by welded on Pens is possible.

FUNCTION

The method by which pot detection works is called described with reference to Figures 1 to 3.

When the radiant heater 11 is put into operation should, the desired power level is on the knob 35 set and thus the controller 31 including the cooking vessel detection 36 is put into operation. This cooking vessel detection works inductively, i.e. the resonant circuit 32 with a relatively high frequency between 1 MHz and 5 MHz excited and the result described below Evaluation of the pot detection is in a manner known per se built up. For details, please refer to the European Patent application 0442 275 A2.

Accordingly, around the wire of the sensor loop 30 generates an alternating electromagnetic field, its properties determines the frequency of the resonant circuit.

If a cooking vessel 51 is now placed on the plate 12, see above this magnetic field is changed, i.e. the sensor loop is damped, which reduces the frequency of the resonant circuit 32 changes. This frequency change is in the pot detection component 36 evaluates and performs when a preset one is reached Threshold values for switching on an or both switches 33, 33a, so that the heating elements 21 flowed and heated accordingly.

The diagram in FIG. 3 shows the relative frequency response df over the diameter, ie the frequency change df in percent of the maximum frequency change during the measurement as a function of the diameter coverage of the hotplate and thus the sensor loop through a cooking vessel. The diagram shows the cross section of the radiator 11 according to FIG. 1 for illustration.

The diagram shows the following: when using a conventional one Sensor coil, which is arranged in the edge 17 would the course shown as a dash-dotted line 52 Frequency change over the diameter result. The one about the The amount of added signal value would be practically proportional the coverage of the circumference. An exactly centered large pot 51a (see FIG. 1) would therefore be a good one Signal, but a slightly smaller pot despite exactly centric coverage no reasonable signal. Would the switching threshold become essential, for example would put below 50% of the total signal size, on the one hand the signal noise that occurs with such sensors and their Arrangement is relatively large, a circuit unreliable and on the other hand an eccentric (shifted) Pot (see double-dotted line 51b in Fig. 2) already lead to an undesired activation.

The ideal curve shown with a solid line in FIG. 3 has two stages, namely the upper stage 54, which corresponds to the large pot 51a covering both heating zones 18, 19 and is intended to switch on both heating zones 18, 19 and a lower mare 55, for example at 50% of the frequency difference df . In the area of this mare, which corresponds to the diameter of the small pot 51, only the central main heating zone 18 should be switched on alone, while at the left end of the mare 55, which indicates the minimum pot diameter for the central heating zone, the signal should drop off quickly.

It can be seen that the one generated by the sensor loop 30 Curve 56 approximates this theoretical ideal curve 53, by generally having a largely linear course the signal size largely corresponds to the covered diameter is proportional, but it is the step shape of the ideal curve contains approximate levels. This makes it possible with just one sensor reliably large from small pots distinguish and above all a distinction between a shifted pot, which cause an activation and a small saucepan to reach the middle main heating zone should start.

The switchover points 57, 58 are shown in the diagram in FIG. 3. At Point 57 (signal level S1) should only be the middle heating zone 18 be switched on and switched on up to switching point 58 remain (switch 33 "ON"). At switching point 58 (signal size S2) the outer heating zone 19 is then switched on (both Switches 33 and 33a "ON"). In other words: the switching point 58 symbolizes the smallest size of the large pot 51a, which is to work with both heating zones during the Switching point 57 indicates the smallest size of a pot 51, which should still lead to an activation.

It can be seen above all that in the area of the switching points 57, 58 the slope of the signal curve 56 is relatively large, so that taking into account a reliable circuit of disruptive factors is possible. At the same time you can see that this is not the case with curve 52 of a conventional sensor coil it is possible.

With regard to the sensor coil, the following happens: Fig. 1 shown cooking vessel 51 is a Pot whose diameter corresponds to that of the central main heating zone 18 corresponds. It covers the area of the heating zone 18 and the corresponding area of the sensor loop 30, that is mainly the inner peripheral portions 38 a signal level which is approximately in the area of the first stage 55 Diagram 3 lies. So this signal lies between the there signal values S1 and S2, so that only the central main heating zone 18 is turned on.

When putting on the larger pot 51a, in addition to the inner peripheral portions 38 also the outer peripheral portions and covers the connecting portions 39 so that there is a stronger signal change. 3 to Recognizing step results from the position of the peripheral sections 37, 38, which are relatively relative when covered result in sharp signal change, while in between relatively flat curve sections corresponding to steps 54, 55 of the ideal curve.

The cooking process is otherwise without any influence through the pot detection either power or temperature controlled and under the supervision of the temperature monitor 24, which protects the glass ceramic plate from overheating.

In the embodiment according to FIG. 4, the function is comparable, only that instead of the concentric arrangement Side-by-side arrangement of the heating zones and their coverage through a correspondingly round or elongated cooking vessel (oval roaster) either only the main heating zone 18 or additionally the additional heating zone 19 is switched on. Even there there is a certain level of gradation through the arrangement of the individual sections of the sensor loop. Above all, however given the step-by-step waveform, to switch depending on the diameter.

In a single-circuit radiator shown in FIGS. 5 to 7 with a heating zone 18, the signal curve is as in FIG. 11 shown. There the ideal curve contains only a level 54 and there, too, is the signal course 56 of the sensor coil 30 the invention largely adapted to this ideal course, so that a steep slope at switching point 58 (smallest possible pot) Signal curve for switching on and off results. In the Curve 52 of a conventional sensor coil would be the switching point are in a range of such small signal sizes that no reliable switching would be possible.

It is therefore a radiant heater with the invention created a pot detection sensor that is not only special simple, robust and retrofittable, but also a sharp and for switching in a wide range provides usable signal. Above all, this allows several Effective areas for pot detection are created so that Pots of different diameters, different heating trigger. With a sensor it becomes a real cooking vessel size recognition possible. It would be, though with a bigger one Construction effort, also possible, e.g. for dual-circuit radiators, to achieve with two sensors according to the invention, wherein compared to an arrangement of two conventional sensors in the outer and intermediate edge both structural and above all result in functional advantages.

Arranged in the area of the heating zone itself a usable for the circuit with the diameter Results provided changes, which are roughly approximated as can be called linearized, but advantageously the 3 and 11 step or step characteristic shown in the diagrams Has.

Claims (14)

Radiant electric heater sensor (11) for the detection of the positioning of a cooking vessel (51) on a hotplate covering the radiator (11) (12), in particular a glass ceramic plate, the Sensor active part of an inductive, preferably by means of Oscillating circuit detuning working oscillating circuit (32) a controller (31) and as a loop (30) electrically conductive material in the area at least one of electric radiant heating elements (21) heated heating zone (18, 19) and this at least partially is arranged across, characterized in that that the sensor loop (30) is rigid, self-supporting and is temperature resistant. Sensor according to claim 1, characterized in that the Sensor loop (30) only one or possibly a few turns having. Sensor according to claim 1 or 2, characterized in that the sensor loop (30) one of a concentricity to the heating zone (18, 19) has a different shape. Sensor according to one of the preceding claims, characterized characterized in that the sensor loop (30) in the edge area the at least one heating zone (18, 19) at a distance from the outer edge and / or an unheated central zone (59) of the radiator (11). Sensor according to one of the preceding claims, characterized characterized in that the sensor loop (30) in radial Distance from each other, essentially in Loop sections (37, 38) running in the circumferential direction has, possibly by several radially directed Connection sections (39) are interconnected. Sensor according to one of the preceding claims, characterized characterized in that the sensor loop made of solid, strong wire, which is particularly uninsulated. Sensor according to one of the preceding claims, characterized characterized in that the sensor loop (30) as a tube is trained. Sensor according to one of the preceding claims, characterized characterized in that the sensor loop (30) from a multilayer material, e.g. a pipe temperature resistant, scale resistant material with a Filling made of a highly conductive material such as copper. Sensor according to one of the preceding claims, characterized characterized in that the sensor loop (30) a Has coating. Sensor according to one of the preceding claims, characterized characterized in that the coating is electrically good conductive material. Radiant heater according to one of the preceding Claims, characterized in that the sensor loop (30) on an insulating material Outer edge (17) and / or a different heating zones (18, 19) delimiting intermediate edge (20) supports, wherein preferably radial connecting sections (39) and / or outward bends (46, 48) of the sensor loop (30) Form support sections. Radiant heater according to one of the preceding Claims, characterized in that the sensor loop (30) a circular or polygonal shape with circumferential section sectors (40) in the form of omega-shaped bulges having. Radiant heater according to one of the preceding Claims, characterized in that the sensor loop (30) made of non-magnetizable material such as one high-alloy steel, e.g. an iron-chromium-nickel alloy consists. Radiant heater according to one of the preceding Claims, characterized in that the sensor loop (30) just below the hotplate (12), possibly above a sensor (26) of a temperature monitor (24) or in same level with it at a substantial distance from the Heating elements (21) is arranged.

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