EP4145959A1 - Induction heating device for an induction stove top and induction stove top - Google Patents

Abstract

An induction heater for an induction cooktop has an induction heating coil spirally wound with a conductor flat from an innermost turn to an outermost turn, with an outer electrical connection to the outermost turn and a flat inner electrical connection to the innermost turn. The inner connection is electrically connected to the innermost turn and runs under the induction heating coil from the innermost turn to the outside. The inner terminal, unlike the conductor of the induction heating coil, is formed flat with a width in a direction parallel to the surface of the induction heating coil about 10 times as large as a height perpendicular thereto. The internal connection extends at least from the innermost turn of the induction heating coil to the outermost turn of the induction heating coil or it protrudes laterally under the induction heating coil.

Description

Field of application and state of the art

The invention relates to an induction heating device for an induction hob, which is designed in particular as an induction heating coil. Furthermore, the invention relates to an induction hob with at least one such induction heating device.

Usually, induction heating coils made of so-called HF stranded wire are wound spirally from an innermost turn to an outermost turn in one plane and in a single layer. Such an HF litz wire can have many individual litz wires, in particular between 5 and 250. Furthermore, it can have a diameter of between 2 mm and 10 mm. An external electrical connection usually leads to the outermost turn of the induction heating coil as a continuation of the HF litz wire and can be connected to clamp or screw connections in the induction hob. In a similar form, an internal electrical connection leads from an innermost turn of the induction heating coil as a continuation of the HF litz wire. In this case, the HF stranded wire runs outwards below the induction heating coil, possibly together with or very close to the external electrical connection or the HF stranded wire of the outermost turn. The disadvantage here is that the HF stranded wire, which is often structurally complicated and requires a lot of space, is guided from the innermost turn to the outside.

task and solution

The invention is based on the object of creating an induction heating device as mentioned at the outset and an induction hob provided with at least one such induction heating device, with which problems of the prior art can be solved and in particular it is possible to improve the structure of an induction heating device and an entire induction hob.

This object is achieved by an induction heating device with the features of claim 1 and by an induction hob with the features of claim 15. Advantageous and preferred configurations of the invention are the subject matter of the other claims and are explained in more detail below. Some of the features are only described for an induction heating device or an induction heating coil or only for an induction hob. Regardless of this, however, they should apply independently both to an induction heating device and to such an induction hob can. The wording of the claims is made part of the content of the description by express reference.

The induction heating device is designed for an induction hob or the hob has at least one such induction heating device. The induction heating device itself advantageously has a carrier which is particularly advantageously somewhat larger than it or than an induction heating coil of the induction heating device. The induction heating coil can be placed on this support and is thus supported for better handling during transport and assembly as well as for better retention in the hob. The induction heating coil itself is wound with a conductor from an innermost turn in spiral turns to an outermost turn, in a plane, advantageously even in a plane. An induction heating coil is in many cases round or approximately circular, but can also be approximately rectangular or approximately triangular. The windings can lie close together at least in regions, but can also be somewhat spaced apart from one another, advantageously divided into regions. The conductor is preferably an HF conductor as mentioned at the outset consisting of a large number of individual strands insulated from one another, which improves the behavior of a power line when driven with currents in the range of a few kHz, for example 10 kHz to 70 kHz. An external electrical connection is provided on the outermost turn of the induction heating coil, with the result that it can advantageously be connected to a converter, possibly via contact devices and/or connecting lines arranged in between. Furthermore, an internal electrical connection is provided, which goes to the innermost turn of the induction heating coil. While the external electrical connection can simply go outwards approximately in the area or plane of the induction heating coil, possibly in a radial direction away from the round induction heating coil, the internal connection runs from the inside outwards under the induction heating coil. So it may go down a bit from the innermost turn and then out under the induction heating coil. It can rest against the underside of the induction heating coil, but this does not have to be the case.

According to the invention, the inner connection is designed differently from the conductor of the induction heating coil or from the conductor of the innermost turn. While in the prior art, as explained at the outset, the innermost turn of HF stranded wire is simply extended and passed under the induction heating coil to the outside, in order to then possibly continue to run together with an external connection to the outermost turn, the invention changes, so to speak the layout of the power line. So it is precisely not the conductor of the induction heating coil or the inner winding that should form the inner connection. This differently designed inner connection is with the conductor of the induction heating coil or the innermost turn electrically connected. Although this can be a detachable connection, it is advantageous if it is non-detachable in order to be safer and, if possible, to have a lower disruptive internal resistance. Furthermore, as one of the main aspects of the invention, the inner terminal is flat and has a width in a direction parallel to the surface of the induction heating coil which is at least twice as large as a height perpendicular to the surface of the induction heating coil or to the width of the inner terminal. Advantageously, the internal connection can be made even flatter, as will be explained in more detail below. Furthermore, the internal connection extends at least from the innermost turn of the induction heating coil to the outermost turn of the induction heating coil. Advantageously, it can still protrude laterally under the induction heating coil, for example by between 0.5 cm and 5 cm. In particular, it can protrude so far below that a connection to a connecting line, in particular a simple cable, is easily possible.

Due to the very flat design of the inner connection, it is possible with the invention to reduce the overall height of the induction heating device. In the prior art, this overall height was usually at least twice the height of the conductor of the induction heating coil, precisely because the internal connection is designed to be considerably flatter and therefore thinner. While the conductor of the induction heating coil or for its windings is between 2 mm and 5 mm thick when configured with the aforementioned HF stranded wire, the specially designed inner connection can be only 1 mm high or preferably even flatter. It obtains the required conductor cross-section from a relatively large width. Induction heating coils, in particular one for the induction heating device according to the invention, usually have a free central area within the innermost turn, which has a diameter of at least 1 cm or 4 cm. Due to the thickness of the HF litz wire used and the very narrow radius, it is not possible to wind all the way to the center point. Thus there is enough space in the middle to create a connection between the inner connection and the innermost turn.

In an advantageous embodiment of the invention, the internal connection is electrically insulated from the outside. This means that it can rest against the underside of the induction heating coil or its windings. Furthermore, no electrical insulation needs to be provided in relation to other parts or areas in the cooktop. Electrical insulation can be a tube with plastic or silicone, alternatively a coating of a suitable material or an insulating varnish, as is known from the HF litz wire for the conductor.

If the inner connection rests on the underside of the induction heating coil or its windings, it can also be attached to it. This is on the one hand by gluing and on the other possible with a double-sided adhesive tape. This makes it possible for the position of the inner connection to be defined in relation to the entire induction heating coil or on the induction heating coil, which is important for simple and error-free assembly.

In an advantageous development of the invention, the conductor with which the induction heating coil is wound in the spiral windings from the inside to the outside or from the outside to the inside is continuous and uninterrupted. Furthermore, the conductor is advantageously unchanged along its turns. An electrical tap for measurements or the like can possibly be installed at least at one point. be provided. However, it should be avoided to produce the conductor, for example, from two interconnected, formerly separate pieces. The conductor is particularly advantageously an aforementioned HF stranded wire with 5 to 250 individual strands, which are each electrically isolated in a known manner, in particular with insulating varnish.

In an advantageous embodiment of the invention, the width of the inner connection can be 10 times to 100 times as large as its height. So it can have a height between 0.01 mm and 2 mm, advantageously between 0.1 mm and 1 mm. The width is then correspondingly greater, with a maximum width preferably being 5 cm, in particular a maximum of 2 cm.

In a development of the invention, the inner connection is formed in one piece from a continuous piece of material, that is to say solid, albeit very flat. Metallic material is preferred here, in particular it can be aluminum, copper or brass, ie it can have good electrical conductivity. Other materials such as carbon or graphite or graphene can also be used. In an alternative embodiment of the invention, the inner connection cannot be a separate, independent piece of material, but can be a coating on a carrying device, for example. In particular, the internal connection can be formed as a coating on the aforementioned carrier for the induction heating coil, in which case the carrier should then be electrically insulating. Then, in addition to the aforementioned materials, in particular copper, similar to a printed circuit board, carbon or carbon-based coatings are also possible. Then it is possible that the induction heating coil is arranged on the support device or the support, possibly fixed, and the conductor of the innermost turn is electrically connected to the inner connection formed as a coating. In principle, this can be done in many ways; the free end of the conductor of the innermost turn advantageously has a screw connection with a flat and planar connection end. The connection end is placed on the inner connection or a contact field of the inner connection and screwed tight or mechanically connected. This can possibly also include attachment of the induction heating coil to the carrier or the carrying device support. Furthermore, the space required for this is not very large. At an outer end, the inner connection can also have a contact field as a coating, to which a connection line is electrically connected in the same way, which can be designed considerably more simply than the HF litz wire. It is thus possible to integrate the internal connection, so to speak, into the support for the induction heating coil.

In an alternative embodiment, the inner connection can be coated with plastic or surrounded by plastic. The plastic can be designed to fix the induction heating device or the induction heating coil, as a support for the winding and/or as electrical insulation, possibly also as thermal insulation. In addition to an internal connection, further conductors, for example for connecting sensors, can be embedded or injected in a plastic, which can be arranged above the induction heating coil, in particular in a central area. For example, you can record the temperature or a cooking vessel that has been set up.

An electrical connection of a connection line to an outer end of the inner connection is advantageously carried out at the edge or outside of the induction heating coil. It is particularly advantageous for this to be detachable, with plug connections or screw connections being preferred. It can generally be provided that the internal connection is connected to its connecting line in exactly the same way as the external connection is connected to its connecting line. In this way, uniform systems can be used.

A special possibility for an electrical connection can provide that a cap is applied to a free end of the conductor of the innermost turn, alternatively or additionally also of the conductor of the outermost turn, in order to provide a cast aluminum connection to a connection or to a connecting line. In the case of the innermost turn, this is then the inner connection according to the invention; in the case of the outer turn, this would be an aforementioned connection line. Such a cast aluminum connection can possibly also be squeezed, similar to a crimp connection.

Furthermore, it is possible for an aforementioned spherical cap to be formed on the inner free end and/or on the outer free end of the inner connection, with which a cast aluminum connection can also be produced. This cast aluminum connection is used for the transition to an essentially round wire strand, which on the one hand can be an HF stranded wire for the windings of the induction heating coil and on the other hand can be a wire strand of a connecting line.

In order to achieve good functioning of the entire induction heating device, provision can be made for ferrite material to be provided under the induction heating coil, which material can be distributed over a surface or can be arranged distributed over a surface. Such ferrite material is commonly provided under an induction heating coil to concentrate magnetic flux upwardly into a cooking vessel to be heated. Furthermore, under the induction heating coil arranged components of a hob or the like. be protected from the magnetic fields. Such ferrite material can cover at least 80% of the area of the induction heating coil in an induction heating device. It can advantageously be provided that less ferrite material is provided in the area of the inner connection or that it is either thinned out or even left out along the inner connection. In a thinning, the ferrite material can be at least 10% thinner than usual. As a result, the reduced thickness of the ferrite material in the thinning and the height of the inner connection add to the height of the pure induction heating coil with its windings of HF litz wire. If the ferrite material is completely removed with a recess and this recess has the width of the inner connection or is a few mm wider, a minimum height for the induction heating device can be achieved. If the inner connection consists of an aforementioned metal, then a certain protection of the underlying components is also provided. Furthermore, the other provision of the ferrite material, advantageously in a planar manner, is sufficient to bundle the magnetic flux. Such a gap can be between 3% and 10% of the area of the ferrite material or the induction heating coil, advantageously a maximum of 5%. Thus the ferrite material can cover at least 90% or even at least 95% of the area of the induction heating coil. A thickness of the ferrite material can be between 1 mm and 5 mm.

Furthermore, it is possible for a planar configuration of the ferrite material to be in the form of a ferrite foil. It can be attached or glued to the underside of the induction heating coil. Furthermore, the ferrite material can also be fastened as a type of coating on an aforementioned carrier for the induction heating coil, for example also be glued. In this way, an advantageous integration of the various components of the induction heating device can be achieved.

At least one induction heating device according to the invention can be provided in a finished induction hob which has a hob plate. A type of flat support, often also referred to as a support plate, runs underneath the hob plate, on which several or all induction heating devices are arranged. They are then applied or pressed against the underside of the hob plate. Control components and the like for the induction hob can be provided below the surface support, in particular power electronics or converters. The induction heating coils or induction heating devices are attached to these converters electrically connected as usual, this is advantageously done by means of the aforementioned connection lines. These connection lines can go from the induction heating devices directly to a converter or to electrical connections arranged in between, for example connection terminals or plugs.

These and other features emerge from the claims, the description and the drawings, with the individual features being realized individually or in combination in the form of sub-combinations in one embodiment of the invention and in other areas and are advantageous and protectable in their own right Designs may represent for which protection is claimed here. The subdivision of the application into subheadings and individual sections does not limit the general validity of the statements made under them.

Brief description of the drawings

Fig. 1

eine Draufsicht auf eine vereinfachte Darstellung einer erfindungsgemäßen Induktionsheizspule als Induktionsheizeinrichtung,

Fig. 2

eine Seitenansicht der Induktionsheizspule aus Fig. 1,

Fig. 3

eine starke Vergrößerung einer Draufsicht auf einen flachen Innenanschluss für eine innerste Windung der Induktionsheizspule,

Fig. 4

eine Draufsicht auf die Induktionsheizspule mit einer Ferritschicht an ihrer Unterseite, in der eine Ausnehmung für den Innenanschluss vorgesehen ist,

Fig. 5

eine vergrößerte seitliche Schnittdarstellung durch ein erfindungsgemäßes Kochfeld mit einer erfindungsgemäßen Induktionsheizspule auf einem Tragblech und Baueinheiten darunter,

Fig. 6

eine alternative Anschlussmöglichkeit für die innerste Windung an den Innenanschluss mit schräg gewickeltem Ende,

Fig. 7

eine Seitenansicht und eine Draufsicht auf eine alternative Ausgestaltung eines Innenanschlusses, an den das freie Ende der innersten Windung durch Einrollen elektrisch angeschlossen und mechanisch verbunden ist,

Fig. 8

die Herstellung einer vorgenannten Alugussverbindung,

Fig.9 und 10

Darstellungen einer weiteren Ausführung einer erfindungsgemäßen Induktionsheizspule als Induktionsheizeinrichtung

Exemplary embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

1

a plan view of a simplified representation of an induction heating coil according to the invention as an induction heating device,

2

Figure 1 shows a side view of the induction heating coil 1 ,

3

a high magnification of a plan view of a flat inner terminal for an innermost turn of the induction heating coil,

4

a plan view of the induction heating coil with a ferrite layer on its underside, in which a recess is provided for the internal connection,

figure 5

an enlarged lateral sectional view through a hob according to the invention with an induction heating coil according to the invention on a support plate and structural units underneath,

6

an alternative connection option for the innermost winding to the inner connection with a diagonally wound end,

7

a side view and a top view of an alternative embodiment of an inner connection to which the free end of the innermost turn is electrically connected by curling and mechanically connected,

8

the production of the aforementioned cast aluminum connection,

Fig.9 and 10

Representations of a further embodiment of an induction heating coil according to the invention as an induction heating device

Detailed description of the exemplary embodiments

In the 1 1 is a plan view of an induction heating coil 11 according to an induction heating device according to the invention, which is arranged on a round support 13. FIG. This can consist, for example, of plastic or mica or mica. The induction heating coil 11 is spirally wound with an HF braid 15 in turns, from an innermost turn 21 counterclockwise around an inner space 23 outwards to an outermost turn 18. The turns can be close to one another or else regionally or generally one distance from each other. The innermost coil 21 has a free end 22 . The outermost turn 18 has a free end 19 . Both free ends 19 and 22 are electrically connected. The free end 19 of the outermost turn 18 is connected to a conventional connection line 35 with an external connection 20, which is not shown in detail here. The free end 22 of the innermost turn 21 is connected to an inner connection 25 according to the invention, for example welded or soldered. The inner connection 25, which is explained in more detail below and 3 shown in plan view is flat or thin and wide and is advantageously made of copper or aluminum. How from the 1 and also from the side view of the 2 can be seen, its length corresponds approximately to the radius of the induction heating coil 11. Its inner free end protrudes into the interior space 23. Its outer, free end protrudes from under the last or outermost turn 18, so that it is easy to reach. The connection line 35 is electrically connected to this outer free end of the inner connection 25 . This is discussed in more detail below.

The side view of 2 shows clearly how flat the inner connection 25 is designed and that the overall height of the induction heating coil 11 is therefore only slightly higher than the pure diameter of the windings 16 or the corresponding HF stranded wire 15. The thickness of the carrier 13 may also be added to this , which can also be relatively small. Furthermore, a recess corresponding to the dimensions of the inner connection 25 can be provided in an upper side of the carrier 13 so that this inner connection 25 is at least partially sunk into the carrier 13 . Not shown in 2 , but of course there is the outermost winding 18 with its free end 19, which is also electrically connected to a connecting line 35 with an external connection.

From the enlarged plan view of the inner terminal 25 according to FIG 3 it can be seen that the left free end clearly protrudes beyond the innermost turn 21 shown in dashed lines into the interior space 23 . An inner contact pad 27 is provided thereon. The free end 22 of the HF stranded wire is brought up there and, for example with individual stranded wires distributed somewhat across the width, is welded to the inner contact field 27 by means of a welded connection 28 . Instead of the welded connection 28, soldering can also be used, or an aforementioned cast aluminum connection can be produced.

The right-hand free end of the inner connection 25 protrudes beyond the outermost winding 18 shown in dashed lines, so the inner connection 25 is guided over the induction heating coil 11 or over the windings 16 . A connection to the connecting line 35 takes place here by means of a connecting eyelet 30 which is clamped onto the stripped conductor of the connecting line 35 in a known manner. An eyelet part 31 of the connection eyelet 30 is screwed flat with a screw (not shown) and a fastening nut 33 either directly onto one side of the inner connection 25 or onto a contact field provided thereon and forms a known good surface contact.

The two in 3 connection options shown can also be interchanged or used arbitrarily. While at the inner free end of the inner connection 25 the free end 22 of the innermost turn 21 should be fixed on a top side of the inner connection 25, it is irrelevant for the connection line 35 at the outer free end. The underside can possibly also be used here in order to reduce the overall height upwards.

In the 4 1 shows a plan view of the induction heating coil 11, with the windings 16 being shown as a circle, so to speak. An innermost coil 21 around the inner space 23 is attached to the free end 22 at the inner free end of the inner connection 25, for example welded accordingly 3 . While the outside diameter of the induction heating coil can be about 20 cm, for example, the diameter of the interior space 23 can be about 2 cm to 4 cm. The inner connection 25 runs below the windings 16 and is shown in dashed lines. On the outside, a free end protrudes about 8 mm below the windings 16, and here an electrical contact is made with the connection line 35 by means of a connection eyelet 30 accordingly 3 . Below the windings 16, the inner connection 25 is shown in broken lines.

The outermost winding 18 is connected or contacted with its free end 19 to a connecting line 35 by means of an external connection 20 . The connection lines 35 can also be connected to one another or twisted or have a common sheath. Here is Optimization of logistics is also possible because the connection length of induction heating coils does not vary during production, but only when they are installed in a cooktop. By connecting the connection lines to the free end of the innermost turn and to the free end of the outermost turn of the induction heating coil, it is possible to precisely cut these connection lines to length. The induction heating coils themselves then do not need to be specified with regard to a connection length.

A ferrite layer 37 is provided under the windings 16, shown here by the hatching, in order to close the magnetic flux downwards when the induction heating coil 11 is in operation. The ferrite layer 37 can be, for example, a rigid or flexible part with a thickness of 1 mm to 5 mm, advantageously 2 mm to 3 mm. This is considered sufficient for the magnetic flux.

A corresponding recess 38 is provided in the ferrite layer 37 along the inner connection 25 . Depending on the height of the inner connection 25 on the one hand and the thickness of the ferrite layer 37 on the other hand, the ferrite material in the recess 38 can be completely removed or only made thinner, for example only 10% to 50% of the thickness of the ferrite layer 37.

Furthermore, the dotting shows that the ferrite layer 37 does not have to be a continuous layer, but can also be divided into individual circle segments 39, for example 8 to 10 pieces. This can improve or facilitate manufacturability.

In the figure 5 a lateral sectional view through a hob 40 according to the invention is shown. The hob 40 has several induction heating coils under a hob plate 41, advantageously consisting of glass ceramic, a single induction heating coil 11 is shown. Foil applied to an underside 42 of the hob plate 41 or pressed. It can be seen that either the ferrite layer 37 or the internal connection 25 runs below the windings 16, similar to that in FIG 4 shown in plan view. This then rests on a carrier 13 which in turn rests on a support plate 44 . The support plate 44 is advantageously made of aluminum and thus closes off the magnetic field lines even better at the bottom. A controller 45 and a converter 46 are arranged below the support plate 44, with which, for example, this induction heating coil 11 can be operated directly. These components 45 and 46 are to be protected from the magnetic field generated by the induction heating coil 11 . In addition to the support plate 44, the ferrite layer 37 in particular is used for this purpose.

In the 6 Another way is shown of how the free end 22 of the innermost turn 21 can be electrically connected to the inner terminal. For this purpose, this free end 22 is hit or clamped into the corners of the free inner end of the inner connection 125 from two sides. First this will be in 6 upper corner of the free inner end beaten over the free end 22 of the innermost turn 21, then the lower corner. After that, it can still be pressed. In addition, it may also be soldered or welded.

Another possibility is in the 7 shown in side view and top view. A flat, wide and long internal connection 225 is also provided here, for example made of copper or another metal. Its free inner end is formed as a coiled end 226, whereby the free end 22 of the innermost turn 21 is, as it were, wrapped therein. This results in a significantly improved surface contact compared to that of 6 . The free end 22 is then more or less contacted or connected along a large part of its outside across the width of the inner connection 225 . It is sufficient here if the free inner end of the inner connection 225 is wound up a little more than once, for example 1.5 times or 2 times. An electrical contact is then no longer changed anyway after the first winding or does not improve, only the stability of the connection can be increased. So this is another way to electrically connect the free inner end 22 of the innermost turn 21 to the inner terminal 225 .

In the 8 is divided into three steps, showing how an aforementioned cast aluminum connection can be produced. At the end of an inner connection 325, a round or cylindrical sleeve 348 is formed or arranged in an electrically conductive and mechanically fixed manner. The sleeve 348 has an interior 349 which is designed as a blind hole. An innermost winding 321 with the free end 322 is brought in from the right, and the free end 322 is inserted into the interior space 349 according to the second illustration. There is a certain amount of play or a gap. Liquid aluminum is introduced into this gap as cast aluminum 350, so that in the finished connection according to the bottom illustration, the innermost winding 321 is fixed with its free end 322 in the sleeve 348 and on the inner connection 325 and, above all, is electrically reliably connected.

From the 9 in cut oblique view and the 10 another embodiment of an induction heating coil 311 according to the invention is shown as an induction heating device in a slightly more supervising rotated oblique view, in which the electrical connection to an innermost turn 321 of the induction heating coil 311 is designed with a previously shown cast aluminum connection as explained above. On a wide and thin inner terminal 325, advantageously similar to the previous embodiments, am inner end, which extends into a free interior 323 of the windings 316 and runs below a carrier 313, a sleeve 348 is formed or attached. This is a sleeve as described above 8 has been presented. It can be soldered or welded to the inner connection 325, alternatively it can be produced in one piece with it, in particular it can be cast. The sleeve 348 is open at one end toward the free end 322 of the innermost coil 321 . The free end 322 of the innermost coil 321 is tucked in and according to the method of 8 fastened or held in it as a cast aluminum connection and electrically connected. The sleeve 348 at the inner end of the inner connection 325 protrudes upwards through an opening 314 in the carrier 313 so that the connection with the innermost winding 321 is above the plane of the carrier 313 .

As can be seen from the sectional view of the 9 As can clearly be seen, the thickness of the inner connection 325 increases the overall thickness or the induction heating coil 311 somewhat, namely by exactly its own thickness. However, this is clearly recognizable as being considerably less than the thickness of the innermost winding 321, even if this were to run below the carrier 313 with the flatter horizontal extension of its somewhat flattened cross section.

At the outer end of the inner connection 325, an outer sleeve 354 is attached in the same way, which either also has an opening to an inner space at one end or is provided centrally and at right angles thereto. The corresponding connection line 335a is inserted here in the same way as previously described for the innermost turn 321 and is fastened as an aluminum cast connection and electrically connected.

An electrical connection of the outermost turn 318 can take place either in a similar or the same way, alternatively the outermost turn 318 can simply be continued here and form the other connection line 335b. Both possibilities are conceivable here.

From the 9 can also be seen that strip-shaped spacers 352 are applied to the top of the induction heating coil 311 or the windings 316. They are made of plastic and define a distance, for example, to a glass ceramic plate or hob plate above it, on the underside of which the entire induction heating coil 311 is then placed or pressed.

The aforementioned ferrite layer cannot be seen in the sectional illustration, since it is recessed around the flat inner connection 325 . It can be arranged either on the top of the carrier 313 or on its underside. With an arrangement of the ferrite layer on On the underside, it can be made thinner as an alternative to a recess in the area of the inner connection 325 . This has been explained above.

Claims (15)

Induction heating device for an induction hob, the induction heating device having: - an induction heating coil wound with a conductor from an innermost turn in spiral turns to an outermost turn in a plane, especially in a plane, - an external electrical connection to the outermost turn of the induction heating coil, - an internal electrical connection to the innermost turn of the induction heating coil, the internal connection running under the induction heating coil from the innermost turn to the outside, characterized in that : - the inner connection is designed differently than the conductor of the induction heating coil, preferably as the conductor of the innermost turn, - the inner connection is electrically conductively connected to the conductor of the induction heating coil or the innermost turn, in particular is non-detachably connected, - the inner terminal is flat with a width in the direction parallel to the surface of the induction heating coil which is at least twice as large as a height perpendicular to the surface of the induction heating coil, - the internal connection extends at least from the innermost turn of the induction heating coil to the outermost turn of the induction heating coil or the internal connection protrudes laterally under the induction heating coil. Induction heating device according to Claim 1, characterized in that the internal connection is electrically insulated from the outside. Induction heating device according to Claim 1 or 2, characterized in that the internal connection bears against the underside of the induction heating coil or the windings, in particular is fastened thereto. Induction heating device according to one of the preceding claims, characterized in that the width of the inner connection is 10 times to 100 times as large as the height. Induction heating device according to one of the preceding claims, characterized in that the inner connection is made in one piece from a continuous piece of material is formed, preferably made of metal, in particular copper, aluminum or brass. Induction heating device according to one of the preceding claims, characterized in that the internal connection is connected to the conductor by means of a connection type from the following group: soldering, welding, aluminum casting, pressing. Induction heating device according to one of the preceding claims, characterized in that the inner connection as a coating is arranged firmly on a support device, preferably on the carrier for the induction heating coil, with the induction heating coil in particular resting on the carrier, the inner connection being under a free end of the conductor of the innermost turn and is electrically connected to it, preferably by means of a screw connection of a connection end of the free end of the conductor to a contact pad of the inner connection. Induction heating device according to one of the preceding claims, characterized in that a connection line is connected to an outer end of the inner connection at the edge or outside of the induction heating coil, in particular is detachably connected, preferably by means of a plug connection or screw connection, in particular the outer connection being connected to the connection line in the same way like the inside connection. Induction heating device according to Claim 8, characterized in that a cap is applied to a free end of the conductor of the innermost turn and/or the outermost turn for a cast aluminum connection to a connection or to a connecting line. Induction heating device according to Claim 8 or 9, characterized in that a cap is formed on the inner free end and/or on the outer free end of the inner connection for a cast aluminum connection to a connection, preferably for a cast aluminum connection for the transition to a substantially round wire strand. Induction heating device according to one of the preceding claims, characterized in that ferrite material is provided under the induction heating coil, preferably distributed over a large area, in particular covering at least 80% of the surface of the induction heating coil, with less ferrite material being provided in the area of the inner connection or a thinning or recess along the internal connection in is formed from the ferrite material, the ferrite material being thinner in the thinning or being removed entirely in the recess. Induction heating device according to Claim 11, characterized in that the ferrite material covers at least 90% of the surface of the induction heating coil and runs like the internal connection on the underside of the induction heating coil, the ferrite material having a thickness between 0.5 mm and 5 mm, in particular between 0.8 mm and 2 mm, the ferrite material preferably being a ferrite foil. Induction heating device according to Claim 11 or 12, characterized in that the thickness of the ferrite material in the area of the inner connection is less than in the rest of the area next to the inner connection. Induction heating device according to one of the preceding claims, characterized in that the inner connection is coated with a plastic, the plastic preferably forming a fixation and/or forming an electrical insulation of the induction heating coil. Induction hob with several induction heating devices, wherein at least one induction heating device is designed according to one of the preceding claims, characterized in that the induction hob has: - a hob plate, - a surface support on which the induction heating devices are arranged and are applied to the hob plate from below, - Converter below the surface support, the induction heating coils being electrically connected to the converter with connecting cables.

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