EP0757508A2 - Cooking hob with a plurality of cooking zones disposed underneath a plate - Google Patents

Abstract

The hob has several cooking points (12) contg. heating elements in a heating zone (13,13a) and thermal insulation, esp. radiation cooking points, arranged inside a trough (14) of flat material, esp. sheet metal. The thermal insulation for each cooking point is separately mounted directly on the trough. The unit (11) forms a prefabricated, connectable component with an integrated control, regulation, monitoring and connection system which contains all the control, regulation, monitoring and connection devices as far as the mains system and any adjustment and input devices.

Description

APPLICATION AREA AND PRIOR ART

The invention relates to a hob unit with a plurality of heating elements arranged below at least one plate, in particular a glass ceramic plate, arranged in at least one heating zone, and hotplates containing thermal insulation, in particular radiation hotplates, and a process for their production.

Usual cooktop units of this type consist of a metal hob which is arranged on the underside of a glass ceramic plate or which carries the plate itself. In it, individual radiant hobs are arranged, which themselves have a sheet metal carrier shell in which the heating elements are attached to thermal insulation material. Each individual radiant heater is pressed against the underside of the glass ceramic plate by resilient mounting parts engaging on the carrier shell (cf. DE 27 60 339 C2 and DE 36 13 902 A1).

It has also become known to provide radiant heaters which have a plurality of heating zones within a hotplate, which can be optionally switched on or off in order to change the shape and size of the hotplate (cf. DE 29 43 477 C2). From DE 27 60 339 C2 it is also known to arrange rings on the insulation lying on a support plate which delimit a plurality of heating fields of a multi-unit cooking appliance provided with heating conductors. The previous concept with such hob units always assumed that the radiant heaters forming the hotplates are individual, individually manufactured and functioning units that are provided with the proportion of control, monitoring or regulating units or their sensors and connections that they receive. These units were manufactured, tested and stored independently of one another. In a second production stage, these units were then arranged in a sheet metal trough and finally provided with the control input or setting devices independent thereof and the associated mains connections. In connection with this description, this was and is true both for independent cooktops that can be used in the opening of a worktop of a piece of kitchen furniture, as well as for the cooktops of a special cooker or individually set-up cooking appliances with several hotplates, which are all referred to here as cooktop units.

TASK AND SOLUTION

The object of the invention is to provide a hob unit which enables simplified production, assembly and testing, in particular enables the saving of components and enables improved thermal insulation in the case of predetermined spatial conditions.

This object is solved by claim 1 and the independent method claim.

Due to the individual arrangement of the thermal insulation in the trough, preferably in the form of separate molded parts, the separate sheet metal support shells can be dispensed with for each hotplate. This makes it possible to make the thermal insulation thicker, particularly downwards, so that it utilizes the entire space available, which is limited by the installation depth. To the side, the thermal insulation can be designed independently of any basic shapes and does not always have to correspond to the heating zone in its shape.

The individual thermal insulation components can be guided directly on receptacles belonging to the trough, for example on sheet metal tabs punched out of the trough and optionally bent up at the corresponding points. The desirable pressing of the upper, usually ring-shaped boundary part of the thermal insulation, which surrounds the heating zone, against the underside of the plate can be done by resilient spacers acting directly on this boundary part. The heating element carrier, which is an independent component, can remain on the trough bottom, so that the thermal insulation behaves practically telescopically and thus makes ideal use of the height. However, it is also possible to form the sheet metal trough in two parts, namely from a peripheral frame and a part containing the floor, both of which are loaded by spring means provided on the edge in the sense of compression. As a result, the suspension can be carried out jointly for all hotplates, and the plastically deformable spacers can be used to align the individual hotplates to adapt to the plate.

The possibility of producing the hob unit directly and without the intermediate stage of the individual radiant heaters saves numerous manufacturing, storage and assembly steps. Above all, the unit can form a prefabricated, connectable component together with an integrated control, regulating, monitoring and connection system. By combining the control functions of the individual hotplates, it is sometimes also possible to use more complex components which control the individual functions in parallel and serial information processing, for example pan detection, i.e. the control of the switch-on process depending on the placement of a suitable cooking vessel. By assembling all of the components forming the hob unit, it is also possible to automate assembly processes which, up to now, could not be automated or could only be automated with difficulty, for example the wiring and welding thereof to the individual components.

It is also possible to use the thermal insulation in an optimal way by choosing the material, type, composition and density as well as processing exactly according to the requirements. For example, for the parts that are particularly critical in terms of strength, such as, for example, the delimitation of the heating zones, where a sharp visual separation is important, a more rigid thermal insulation material is used than for the insulating underlay, while, for example, in the case of the heating element carriers, in addition to the thermal insulation properties, particularly also those Temperature resistance is important.

If the boundary part is spanned by a ring, this can form an induction coil for a pot detection system. However, it is also suitable for forming an outer clamp that holds the boundary part together, which, particularly when the boundary part is composed of several ring sectors or sections, can be combined to form a ring. In this case, an outer, e.g. flange-like projection of the heating element support can be positively enclosed, so that after the ring is tightened, a hotplate unit is formed which is self-contained without requiring a special support shell.

It is also possible, without a multi-part ring, to produce such a form-fit fixing that the inserted heating element carrier tablet is subsequently deformed in its edge area by a stamp in such a way that it penetrates into depressions on the inside of the limiting part. The delimiting part can be fiber-free, for example made of vermiculite, and can also be formed as a “sandwich construction”, if appropriate by air chambers or chambers filled with even better heat-insulating material. The ring, which can be mechanically closed, but can be electrically open, can also form the mechanical holder for other components, for example a temperature limiter, which can be attached to it by means of snap connections. It is also possible to provide this element with a clip which engages on the edge, which holds the limiting part and the heating element carrier together and possibly forms a spring element.

In addition to the claims, these and other features also emerge from the description and the drawings, the individual features each individually or separately several can be realized in the form of sub-combinations in one embodiment of the invention and in other fields and can represent advantageous and protectable designs for which protection is claimed here. The division of the application into individual sections and subheadings do not limit the general validity of the statements made under these.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine perspektivische Ansicht einer Kochstelleneinheit (ohne Glaskeramikplatte)

Fig. 2

einen vertikalen Teilschnitt durch die Einheit,

Fig. 3

eine perspektivische, teilgeschnittene Detailansicht eines Teils der Mulde

Fig. 4

ein Detail der Befestigung eines Temperaturbegrenzers,

Fig. 5

eine schematische Draufsicht auf eine Kochmuldeneinheit

Fig. 6

ein Detail der Befestigung einer Topferkennungsspule im Schnitt

Fig. 7

die Ausführung nach Fig. 6 in Draufsicht,

Fig. 8 und 9

weitere Ausführungsformen der Befestigung einer Induktionsspule für die Topferkennung,

Fig. 10

ein Detail der Verlegung von Anschlußleitungen,

Fig. 11

einen Teilschnitt mit einer zusammengesetzten Ausführung des Begrenzungsteils,

Fig. 12

ein Blockschaltbild eines Steuergerätes,

Fig. 13

eine perspektivische Ansicht einer Kochstellen-Einheit

Fig. 14

einen Teilschnitt durch Fig. 13

Fig. 15 bis 17

Varianten im Teilschnitt

Some embodiments are shown in the drawing and are explained in more detail below. Show it

Fig. 1

a perspective view of a hotplate unit (without glass ceramic plate)

Fig. 2

a partial vertical section through the unit,

Fig. 3

a perspective, partially sectioned detailed view of part of the trough

Fig. 4

a detail of the attachment of a temperature limiter,

Fig. 5

is a schematic plan view of a hob unit

Fig. 6

a detail of the attachment of a pot detection coil in section

Fig. 7

6 in plan view,

8 and 9

further embodiments of the attachment of an induction coil for the pot detection,

Fig. 10

a detail of the laying of connection lines,

Fig. 11

a partial section with a composite version of the boundary part,

Fig. 12

1 shows a block diagram of a control device,

Fig. 13

a perspective view of a hotplate unit

Fig. 14

a partial section through Fig. 13th

15 to 17

Variants in partial section

CONSTRUCTION OF THE COOKER

Figures 1 and 2 show a hob unit 11 with four hotplates 12, three of which are individual hotplates of different sizes, each with only one heating zone 13, while the fourth has two heating zones, one of which, like the other hotplates, is circular, can also be switched on individually is, while the adjoining heating zone 13a to form an elongated hotplate, for example for heating an oval oven, can be switched on.

The hotplates 12 are arranged in a depression 14 which has an edge 15 with a horizontal, circumferential support shoulder 16 for receiving a plate 17, preferably a glass ceramic plate. A raised outer edge 18 centers the plate and surrounds the outer edge. The hob is usually rectangular in shape with a corresponding arrangement of the hotplates in the square.

The trough 14 consists of a rectangular, relatively flat sheet metal shell with side walls 19 and a bottom 20. In the interior 21, the hotplates are arranged without their own sheet metal carrier shell. They are made up of individual thermal insulation components 22, which are attached to the trough individually and directly, but in mutual interaction. One of the thermal insulation components is a disk-shaped heating element carrier, which is partially received and centered in a depression 26 in the sheet metal recess. Between the surface 24 of the heating element carrier 23 and the plate 17 there is a distance which forms the heating chamber 27 of the heating zone 13.

It is surrounded by the other thermal insulation component in the form of a limiting part 28, which is annular. It is connected via an angular, circumferential recess 80 to the heating element carrier 23 on its outer circumference and extends to the plate 17, where it rests resiliently. This suspension is produced in the embodiment according to FIG. 2 by resilient spacers 81, which are designed as sheet metal spring parts punched out and bent out of the material of the trough bottom 20. They press on the underside of the limiting part 28, which is designed as a ring with an L-shaped cross section, and press it upward against the plate 17. By overlapping and interlocking with the heating element carrier, they can move vertically relative to the latter without a radiation or convection gap in the heating chamber 27 to accomplish.

Furthermore, side holders 82 are provided on one side of the limiting ring 28, which can also be designed as sheet-metal tabs bent out of the sheet material of the trough bottom in an L-shape. They engage with their horizontal legs in recesses 84 in the outer circumference 86 of the annular limiting part 28 and fix it to the left and also in the transverse direction in relation to lateral movements in FIG. 2. One or two of these side holders can be provided relatively close together. Opposite it is a side holder 83 which is designed as a Z-shaped sheet metal tab. Its upper, essentially vertical leg 85 lies parallel to the outer side 86 of the limiting part. A hole 87 is provided in it, which is aligned with a corresponding horizontal hole 29 in the limiting part. An additional side holder, also designed as a sheet metal tab 89 lies in the same circumferential area as the side holder 82 and supports an outer surface 30 of the heating element carrier 23 and, with an obliquely inward bend, also partially engages in an oblique corner recess.

For assembly, the heating element carrier 23 is inserted obliquely from the right in FIG. 2 so that it rests with its outer surface 30 on the side holder 89, and then lowered into the position shown in FIG. 2, so that it is then received in the recess 26 . Then the annular limiting part 28 is inserted obliquely in the same way, so that its side holder 82 engages in the recess 84. This is large enough to ensure that it intervenes even when tilted. Then the limiting part is brought into the position shown by tilting it clockwise, partially surrounding the heating element support. A rod-shaped temperature sensor 31 of a temperature limiter 32 is then inserted through the holes 87 and 29 which are aligned with one another. They thus form a bolt 90, which fixes the limiting part and thus also the heating element carrier 23 and the temperature controller 32 itself on the trough, but ensures the limited vertical mobility of the limiting part. For this purpose, the hole 29 is made correspondingly large in the vertical direction.

As a result of this arrangement, the delimiting part 28 of each individual hotplate is able to lie down individually with its upper surface on the underside of the plate 17 and thus precisely delimit the heating chamber 27 thermally and optically.

This creates a cooktop unit, which has several cooking zones delimited from one another by outer edges and thermally insulated downwards in a common cooktop contains, without each radiator being closed to the outside by a sheet metal support shell and held together by this. Rather, the fixing takes place on the trough bottom itself, whereby in addition to the preferred fixing by means of sheet metal tabs punched out on the trough bottom, other fastening options, such as screws, pins inserted into holes or other anchoring, are also possible. It is also possible to provide the entire trough bottom with recesses or holes in a certain grid, in which corresponding side holders can be inserted optionally. In this case, a larger variety of types of differently sized and differently arranged cooking zones could be produced with a unit trough.

Fig. 3 shows an embodiment in which the side walls 19 of the trough are divided into two. They consist of an upward leg 91 and a downward leg 92 adjoining the outer edge 15, which runs parallel to the leg 91 outside of it around the trough. This edge component 93, which is formed from the edge 15 and the leg 92, is produced from a sheet metal profile, which then forms a horizontal, slightly bent-down support edge 94 on the outer edge 18, which can rest on a worktop of a kitchen unit, in the opening of which the hob unit 11 is inserted is. This profile could also be made as a continuous casting profile.

Fig. 3 also shows that the two mutually movable legs 91, 92 are connected by a spring wire 95 so that they try to reduce the trough height and thereby exert the contact pressure on the top of the limiting part 28. For this purpose, the spring wire 95 is inserted into outwardly directed, hook-shaped holding tabs, which alternately on the two legs 91, 92 so it is provided that the wire bends in a wave-like manner when inserted and thereby exerts a corresponding spring force.

In this embodiment, the spacers 81 can be designed such that they can be deformed less elastically than plastically. The correct spacing can then be established by a general alignment during assembly, while the permanent suspension, which is also necessary due to a certain tendency to deform in the thermal insulation materials, is maintained by the overall suspension between the plate and the trough.

Fig. 4 shows an attachment of the temperature limiter 32 directly to the trough bottom 20 by means of an angled sheet metal connection part provided on the temperature limiter, which e.g. can be determined by spot welding.

13 shows a hotplate 12 with a heating element carrier 23 and a multi-part limiting part 28. It is ring-shaped overall, but is composed of individual ring segments 28a which are interlocked with one another. On the outer circumference 86, a cup-shaped ring 97 forming the pot detection sensor 44 rotates, which is open at one point and there has two outwardly directed bends 98, the ends of which form tab connectors 99. The ring is clamped together by means of an electrically insulating connecting means, for example a ceramic clamp or a screw 100, and thus clamps the hotplate unit together.

Corresponding flat plugs are plugged onto the flat plug connections 99, which connect the sensor 44 with the corresponding one Connect the control unit for an inductive pot detection system.

Openings 58 can also be provided in the ring 97, into which snap or plug connectors 57 are inserted in order to fix the temperature limiter 32 (see also FIG. 2).

14 shows a partial cross section through the embodiment according to FIG. 13. It can be seen there that the cross-section of the ring segments 28a of the limiting part 28 has a recess 101 which is open towards the inside and into which a corresponding ring projection 102 engages on the outer circumference of the heating element carrier 23. Since the ring segments 28 are held together by the tire or the clamp 97, a coherent hotplate is thus created by the attachment of the pot detection coil.

15 shows an embodiment in which the annular limiting part 28 can be formed in one piece. Here, the cross section of the delimiting part 28 is L-shaped, the short leg of the L lying at the top and pointing towards the inside in order to protrude above the surface 24 of the heating element carrier 23 and to secure it upwards. As in the other versions, the tire 97 also lies around the outer circumference and extends to the upper edge of the limiting part, i.e. to the underside of plate 17.

Fig. 16 shows an embodiment, also with a tire 97, in which the limiting part 28 is integrally formed as a ring. It has a modified L-shape in cross-section, the inwardly projecting L-leg being at the bottom, so that it forms a lower outer edge of the hob component provided with a circumferential recess 102. In the area of this recess 102 there are also blind holes 103 in the fastening part 28 introduced, which can engage in corresponding projections on the trough during assembly. They are also suitable to serve as alignment aids during the automatic insertion process.

The heating element carrier 23 is adapted to the inner shape of the limiting part 28 and accordingly has an upper flange projecting on the circumference and is designed at the bottom with a somewhat smaller diameter. In the area of the outer flange 105, the heating element carrier 23 is fastened to the inside of the delimitation part 28 in that, after insertion, a stamp of material from the heating element carrier (28), which presses down from above, is displaced into formations 106 on the inside of the delimitation part 28. As a result, the heating element carrier 23 is positively locked on the limiting part 28 by deformation of the thermal insulation material. The stamp forms depressions or impressions 107 on the surface 24. This deformation preferably occurs at several points on the circumference, but can also be carried out all around. There is a good hold of the two thermal insulation molded parts to one another, also due to the fact that the deformed material can be somewhat more densely compressed at the deformation points.

The resulting toothing can also be carried out vertically, alone or in addition, instead of horizontally, as shown in FIG. 16. The recesses could be undercut, i.e. expanding, being educated. Depending on the material properties, the limiting part 28 can also be deformed to form a connection.

Through the designs according to FIGS. 13 to 16, a radiant heating hob is created which does not require the usual sheet metal plate. It is also possible due to the Protection of the most stressed parts to do without reinforcing fibers, so that the entire radiant heater can be made fiber-free. The edge can, as will be explained in the following, consist of a relatively rigid material, but can have chambers filled with air chambers or with better heat-insulating material than the other material of the delimiting part 28. For example, it would also be possible to make the shape 106 filled with the material of the heating element carrier 23 larger and to extend it over a considerable portion of the height of the edge formed by the limiting part 28, so that an embodiment similar to FIG. 11 is produced. The ring or tire 97 forming the pot detection coil is mechanically closed, but electrically "open". The connection can be galvanic, as described, or also via an air transformer or other type of transformer, for example with ferrite.

Fig. 17 shows an embodiment in which, with the other similar training as in Fig. 15, the outer surface 86 of the limiting part 28 is formed so that individual clips 108 can be received therein, which are fixed to the limiting part 28 and a piece above the floor 109 extend from the limiting part 28 and heating element carrier 23 and thus hold them together. A spring section 110 can also be provided thereon, which is supported on the base 20 of the trough. Such an embodiment is particularly advantageous for the later replacement of a hotplate in the event of a repair. The clip 108 holds with a lug 111, which engages in a groove 112 on the outer circumference 86 of the limiting part 28. The clip can be made of resilient sheet metal.

THERMAL INSULATION

When choosing the thermal insulation material and its design, in addition to temperature resistance and, if possible, electrical insulation, properties that are normally mutually exclusive must be taken into account, namely good thermal insulation properties and mechanical strength. Under this condition, the material of the thermal insulation components 23 is selected.

For the heating element carrier 23, a fumed silica airgel is preferred, which, mixed with appropriate binders and opacifiers, for example made of metal oxides, forms a tablet-like shaped body, i.e. a more or less thick, the shape of the heating zone is pressed. Reinforcing agents can also be added to increase the mechanical strength, but fibers should be avoided if possible.

Electrical resistance heating elements 25 are embedded in the upper surface 24 facing the heating chamber 27. They consist of thin corrugated tapes, which are pressed upright into the thermal insulation material after the tablet has been pressed, with feet provided on the underside and spade-shaped due to the corrugation. Due to their large surface area, these heating elements have a very short glow time compared to the heating element mass. They are known under the trademark "HiLight" by the applicant. For details of their nature, manufacture and function, reference is expressly made to DE-42 29 373 and DE-42 29 375.

The heating element carrier 23 has an upward projection in the middle on the otherwise flat surface 24 33, on which the temperature sensor 31 of the temperature limiter 32 rests. Depending on the size of the heating zone, this sensor protrudes to the middle or a little further above, so that a uniform temperature sensor length can be selected even with different heating zone diameters. As a result of the HiLight press-in technology, it is normally possible to produce a heating element carrier with adequate thermal insulation quality and mechanical strength, especially if it can have a greater thickness. A particular advantage of the integrated hob concept is that the space that was necessary to arrange the support shell that accommodates the radiant heater and press it upwards is now available for thermal insulation, so that with the same overall height of the hob, some thermal insulation is available Can be millimeters thicker. However, if special requirements, for example an even lower trough height or the like. Require it, there may also be a thermal insulation layer under the heating element carrier, then usually of an even lighter and therefore better thermal insulation material of the same type. A multilayer structure of the heating element carrier tablet is also possible.

The limiting part 28 consists of mechanically stronger material, which is therefore both more rigid and more abrasion-resistant. Such materials can be, for example, felt or paper-like thermal insulation materials formed from slurries of ceramic fibers. However, the aim is to generally avoid fibers in thermal insulation materials. It is therefore preferred to use a very dimensionally stable material, such as vermiculite, an expanded mica which, with very good mechanical properties, is a good electrical insulator with acceptable thermal insulation and temperature resistance properties. The delimiting part 28 is formed from this material, which is particularly sharp is possible, so that it is particularly well suited for the precise optical limitation of the heating zone. Basically, the material has a mechanical consistency like a plastic or integral foam with a closed surface.

In places where particularly high temperature resistance and / or thermal insulation is required, inserts 34 can be provided in the limiting part 28. 11 shows an insert 34 on the side of the delimiting part facing the heating chamber 27. It prevents heat from migrating to the side. The insert is formed in the form of a circumferential ring in a groove 35 in the limiting part 28. The flanges which remain at the top and bottom are not so thermally endangered, since they rest on the plate 17 on the one hand and on the heating element carrier 23 on the other hand. These inserts, made of a different material from the rest of the thermal insulation component, create a composite construction that gives the component the characteristics of both inherently incompatible properties, mechanical strength / good thermal insulation properties. This composite construction can also be used in other respects, for example in the positions surrounding the controller part to be explained later or in other recesses of the limiting part provided from above or from the outside.

CONTROL AND REGULATION

The arrangement of the hotplates shown in Fig. 1 in a common trough makes it possible to combine the control, regulating, monitoring and connecting elements for all hotplates, while they have hitherto been at least related to the components themselves, for example the temperature limiter and connecting lines, heat detectors or pan detection systems were assigned to each individual hotplate.

In Fig. 1 it is shown that the temperature limiters 32 are located in a central area 36 between the four hotplates. It is also possible to accommodate the four temperature limiters, possibly together with hot alarm contacts, which are acted upon by the same temperature sensor, in a common housing 37, from which the temperature sensors start in a star shape. From there, the hotplate connections 38 also run directly to the heating elements. A cable harness 39 indicated in FIGS. 1 and 4 runs from the common housing to the input or display field 40, which in this case has adjustment buttons 41 reaching to the top and through the glass ceramic plate. Instead of a wire harness made of strands or solid wires, a multi-lane matrix made of flat conductors can also be used. Indicator lamps 42 for a hot display are provided in a suitable arrangement in relation to the hotplates. Temperature or power control elements that are influenced by the setting buttons 41 can be provided in the area of the setting field 40 or within the common housing 37.

The residual heat indicator, usually referred to as a hot indicator, ensures that the user is made aware that a hotplate could still be at a dangerous temperature when touched. To operate them, a second contact is normally provided in the temperature limiter, which is actuated by the sensor of the temperature limiter and switches at, for example, 70 ° C. However, the hot display could also work with other, for example electrical, resistance sensors, in particular if common control electronics are present. Can do the same however, also fulfill a control that works in a time-dependent manner depending on the switching on of the hotplates by responding to the hot display with appropriate safety margins if the heating element is switched on for a certain time. It runs for the average cooling time below a dangerous temperature after switching off the heating element and only then switches off the hot display. It can be provided, for example, that a brief, for example inadvertent, switch-on does not yet activate the hot display.

A central regulating and control circuit is shown in the block diagram in FIG. The control device 43 is provided for four hotplates 12, two of which (top left and bottom right) each have a heating element 25, while the other two (bottom left and top right) each have two heating elements, e.g. for a hotplate with two heating zones 13, 13a.

The control unit also contains a pan detection electronics. For this purpose there are induction coils 44 on the hotplates, one for each heating element, which are connected to the control unit. These pot detection sensors are connected to a multiplexer 45, which enables serial processing of the signals. The signals thus arriving are processed in a specially adapted, integrated circuit (ASIC) 46, partly under the control of a microprocessor 47.

The resulting output signals are supplied to power switches 49 via a driver 48, which are shown as electromechanical relays, but can also be designed as electronic power components. In the exemplary embodiment according to FIG. 12, the power control takes place outside of the control device 43 in power control devices 50, which are operated by the adjusting buttons 41 and can be combined as individual or in a common block 51. These power control devices, also known as energy controllers, mostly work with pulse-wise power release and can work electrothermally or electronically.

However, it is also possible to include this power control in the control unit 43 and only to pull out the setting members. This could be any input means, for example rotary encoders, such as potentiometers, or key inputs, preferably touch switches, which may also act through the glass ceramic plate. In such a case, a keypad could be created in the area of the setting field 40, by touching which the user can effect the selection of the individual hotplates and their setting.

The microprocessor also controls the hot display field 42 in the form of light-emitting diodes via a corresponding control 52. In this case, the temperature limiters are provided in terms of circuitry outside the control device 43, but can also be largely structurally associated with it.

The control device is provided in the central area 36. Appropriate thermal insulation protects it from heat from the heating zones. As FIG. 2 shows, it can emit heat via the base 20, possibly also upwards via the glass ceramic plate, if the temperature level borne by the electronics is relatively high. Further measures can contribute to cooling here, for example an interruption of the base 20 around the central region 36, for example through the slots 52 in FIG. 2, in this Area attached heat sink or even by active cooling using a Peltier element.

In any case, a common control unit makes it possible to use functions that are technically relatively complex, such as pan detection, because the effort for several hotplates is hardly greater than for one.

The signals from the pot detection sensors 44 can be evaluated according to the prior art, for example according to DE-40 04 129, the content of which is expressly referred to here.

As a result of the ambient conditions, in particular the high and changing temperature, the arrangement of the pot detection sensors, which are designed as induction coils, is particularly critical. In the figures 6 to 9 different variants are shown, which are each designed as single-winding coils. FIGS. 6 and 7 show an embodiment in which the limiting part 28 has an annular slot 75 extending from its upper side, into which a single-turn loop is inserted as a pot detection sensor 44. It is made of metallic tape material and, as shown in Fig. 7, is slightly corrugated to hold itself in the slot. Their connections lead to the central area 36 and are connected there to the control device 43 with the smallest possible free cable length. Since it is very important to keep these connections as short as possible, individual pan detection components could also be arranged close to the individual cooking zones in the thermal insulation. In this way it is possible to evaluate the relatively unsharp and possibly interference-prone signals of a single-winded induction coil, which may be unshielded in its connection area, with sufficient accuracy.

FIG. 8 shows an embodiment in which the induction coil forming the pot detection sensor 44 is embedded in the material of the delimiting part 28 close to the heating zone 27 in the form of a single-turn round wire, but is shielded from the heat.

FIG. 9 shows an embodiment in which an upright band of flat material is used as the pot detection sensor 44, as in FIGS. 6 and 7, which, similar to the heating conductor 25, is embedded in the heating element carrier 23 by being pressed in over part of its height is. To prevent excessive heating, a reflective coating can be provided on the belt, for example. It is advantageous for these pot detection coils that the respective hotplate is designed without a surrounding sheet metal edge, which could form an unwanted shield.

FIG. 9 shows that an indicator lamp 42 designed as an LED for the hot display can be inserted directly into a recess in a recess of the limiting part 28 and then shines through the plate.

CONNECTIONS

The arrangement described makes it possible to make the connection laying particularly inexpensive. On the one hand, a large part of the internal wiring can be dispensed with by merging the various regulating and control devices, and on the other hand, the individual hotplates can also be connected to the central control unit or other organs during the manufacture of the hotplates and thus also the bowl . When summarized in a wiring harness 39, in which the cables are originally individual switching elements, for example the temperature limiters 32, a common plug (97 in FIG. 1) can finally be provided for connection to the input or setting devices.

Above all, however, the connection is possible by means of a wiring harness 39 or a connection matrix, which can be prepared with precisely specified connection lengths and positions. For example, connections made of solid wire could be guided in corresponding channels of the limiting part 28. An electrical connection consisting of strips or strips 55, which are inserted into corresponding channels 56 in the limiting part 28, is particularly preferred. The channels can also be easily produced within the delimiting part, for example, by staggered stamps. The flat conductors 55 are inserted or inserted into them. However, it is also possible to guide them through corresponding recesses in the parting plane between the delimiting part and the heating element carrier, wherein they are automatically included when these parts are joined together.

The heating conductor tapes can consist, for example, of nickel-plated steel tape, which are optionally connected to one another by spot welding 57. They can also be produced as a corresponding matrix by punching. The lower electrical conductivity of iron can be compensated for by appropriate dimensioning. In any case, this gives heat-resistant and easily weldable conductors.

PRODUCTION METHOD

The hob unit can be produced in a continuous process, since the radiant heaters for the individual hotplates no longer need to be manufactured separately and assembled in a hob, but only emerge from individual basic components when the hob unit is installed.

In detail, the manufacturing process can proceed as follows: In the prefabricated, bowl-shaped metal trough 14, the fastening parts, that is to say the spacers 81 and the side holders 82, 83, which were provided by punchings in the base, are bent up accordingly. Thereafter, the heating element carrier 23 with heating elements 25 attached thereon is automatically, i.e. if necessary, from an automatic handling machine, swung in obliquely (from the top right in FIG. 2) and positioned in the recess 26. Then the limiting part 28 is pivoted in in the same way and inserted between the side holders 82 and 83. Then the temperature limiter 32 is inserted with its sensor 31 through the holes 87, 88, so that the limiting part 28 and thus the entire hotplate is locked in its position. The temperature limiter can be snapped onto the side holder 83 by means of snap elements 57. These snap elements are provided on the side of the head facing the sensor and can consist of a centrally slotted sheet metal part with a barb-like head that snaps into a corresponding opening on the side holder 83.

Before or after the temperature limiters are attached, depending on their position and arrangement, further regulating and control elements are also arranged in the central region 36 of the trough, for example the control device 43.

Electrical connection connections can already be provided on the regulating and control elements, for example on the temperature limiters 32 already having strands in the provided Length and welded with finished ferrules. They are then combined into a cable harness that is led out together. Another option is to insert a prefabricated cable harness that already has its prepared ends in the appropriate lengths and arrangements on both sides.

6 and 7, the pan detection sensors in the form of preferably single-winding coils can then be pressed into the limiting part. This is followed by preferably automatic welding of all connections, i.e. for example the connections for the heating elements 25 provided at the temperature limiters etc.

If an input or setting field 40 is provided directly on the trough, this is introduced beforehand and at the same time connected to the other connections by welding the connections.

After that, the entire hob unit can be subjected to a test process, where not only the correct wiring is checked, but also the heating elements and the controllers in operation.

Together with the pan detection sensors 44, a hot indicator lamp 42 can, if provided, also be inserted into the limiting part and then connected.

Possibly. the glass ceramic plate could already be put on beforehand, with a height adjustment of the individual hotplates being produced automatically in the embodiment according to FIG. 3, if necessary. The test is carried out when the plate is already installed, in the state of use, so that the Plate-related influences can already be taken into account during the test.

Claims (13)

Cooking hob unit with a plurality of heating elements (25) arranged below a plate (17), in particular a glass ceramic plate, arranged in at least one heating zone (13, 13a) and heat points (12) containing thermal insulation (22), in particular radiation cooking points, within a flat material , such as sheet metal, existing trough (14) are arranged, characterized in that the thermal insulation of the hotplates (12) is arranged individually and directly on the trough (14). Hob unit according to claim 1, characterized in that the unit (11) together with an integrated control, regulation, monitoring and connection system forms a prefabricated, connectable component and preferably the control, regulation, monitoring and connection system all control , Control, monitoring and connection devices except for the Mains connection and possibly setting or input devices (40) contains. Unit according to Claim 1 or 2, characterized in that at least one thermal insulation component (22) of each hotplate (12) is guided directly to receiving means (26, 82, 83) belonging to the trough (14), and / or the receiving means (81, 82 , 83) on the trough (14) are designed so that an independent hotplate can be used in the event of a repair. Unit according to one of the preceding claims, characterized in that each hotplate (12) contains two separate heat-insulating components (23, 28), namely a heating element carrier (23), preferably a tablet-like shape, made of pressed, free-flowing heat-insulating material, such as silica airgel, and one made of a relative Shape-resistant, preferably fiber-free thermal insulation material, such as vermiculite, shaped, ring-shaped boundary part surrounding the heating zone, which, in particular in its distance from the trough (14), can be changed by preferably resilient spacers (81), in particular the ring-shaped boundary part (28) and the The heating element carrier (23) can be moved relative to one another in the vertical direction and / or the annular limiting part (28) is received on the trough (14) by side holders (82, 83) and thereon by a temperature limiter (32), preferably by a temperature sensor (31). formed bar is set, the esp on the other hand, it is also determined thereby, where appropriate the spacers and / or side holders (81, 82, 83) or their fastening points on the bottom (20) of the trough (14) are preferably provided as pre-punched and bendable sheet metal cutouts and / or on Trough bottom (20) are arranged in a grid that can be adapted to different sizes and arrangements of hotplates (12). Unit according to one of the preceding claims, characterized in that the trough (14) is resiliently mounted at a distance from the plate (17), preferably by spring means (95) provided between the trough (14) and a frame-like plate carrier (93) are. Unit according to one of the preceding claims, characterized in that in a central area (36) formed between the hotplates (12), electrical connections (38), temperature limiters (32), control sensors, connections of pan detection sensors (44) and / or residual heat indicator signal transmitters (42) are arranged, temperature limiters (32) possibly being attached directly to the trough bottom with a holder and / or electronic components (43), in particular for a pot detection system, are arranged in the central area (36), which are optionally insulated and through thermal decoupling and / or passive or active coolant is cooled. Unit according to one of the preceding claims, characterized in that a residual heat display system (42) for displaying the risk of burns when the hotplate (12) is touched is time-controlled without a temperature sensor and / or is connected as a prewired unit with spring plug connections. Unit according to one of the preceding claims, characterized in that an inductive sensor, in particular consisting of only one turn, for a pot detection system is inserted into a boundary part (28) of the heating zone (13), possibly by embedding or by inserting a preferably corrugated ring made of flat material into a groove (75) and / which extends from the side of the boundary part (28) facing the plate (17) and / or the sensor is arranged in the edge region of a heating element carrier (23), preferably as an upright flat material strip partially embedded in the heating element carrier (23). Unit according to one of the preceding claims, characterized in that thermal insulation components (22) are composed of different thermal insulation materials, inserts (34) made of better thermal insulation material are preferably provided in a relatively rigid thermal insulation component (28), in particular in the heating zone (13 ) surrounding area of an annular boundary part (28). Unit according to one of the preceding claims, characterized in that electrical connections of the hotplate, which preferably emanate from associated temperature limiters (32), are provided preassembled thereon and during assembly to a cable harness (39, optionally provided with a common multiple plug (97) ) are combined and / or the electrical connections (38, 55) are integrated in the thermal insulation components (22) or enclosed between them, in particular in partially undercut channels (56), the electrical connections possibly being as flat conductors (55), preferably on Iron base, are formed and possibly are formed as a punched out matrix. Unit according to one of the preceding claims, characterized in that the limiting part (28) is spanned by a ring (44) which possibly forms an induction coil for a pan detection system, in particular is composed of a plurality of ring sectors (28a) and / or the limiting part ( 28) and the ring (44) form the outer boundary of the hotplate (12). Unit according to one of claims 21 to 23, characterized in that the limiting part (28) is positively connected to the heating element carrier (23), in particular the limiting part (28) has at least one recess (101, 106) into which a part (102 ) of the heating element carrier (23) engages and which is possibly in the region of a deformation of the heating element carrier (23). Method for producing a hob unit (11) with a plurality of electric heating elements (25) arranged below a plate (17), in particular a glass ceramic plate, and hotplates (12) containing thermal insulation, in particular radiation hotplates, in which a) heating element supports (23) provided with electrical heating elements (25) are positioned on the bottom (20) of a metal trough (14) common to all hotplates (12), b) limiting parts (28) are attached over the heating element carriers (23) and locked in a form-fitting manner, c) regulating, monitoring and control devices are arranged in the area of the hob (11), in particular in a central area (36), possibly with the locking of the limiting parts (28), d) pot detection sensors (44), which are designed as induction coils, are introduced into the boundary part (28) in the edge region of the openings, e) if necessary, an input or setting field (40) is mounted, f) electrical connection connections (57) between the connection lines (38, 39, 55) and the heating elements, regulating, monitoring and control devices and, if appropriate, the pot detection sensors (44) and the input and setting field (40) are automatically welded g) and then, if necessary, the entire unit is subjected to a test procedure.

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