BE1030867B1 - Induction heating device for an induction hob - Google Patents

Abstract

The invention relates to an induction heating device (2) for an induction hob (1) with at least one, preferably flat, induction coil (22) which is designed to inductively heat at least one cooking area (11) of the induction hob (1). The induction heating device (2) is characterized by at least, preferably exactly, one ferrite surface (24) which is arranged facing away from the cooking area (11) at least substantially flat and parallel to the induction coil (22).

Description

Description

Induction heating device for an induction hob

The invention relates to an induction heating device for an induction hob and an induction hob with at least one such induction heating device.

It has long been known to use inductively operated hobs for cooking, frying, etc. Instead of heating the cooking zones of the hob through electrical current heat losses, an electromagnetic

Alternating field is generated by at least one coil of a cooking zone. The electromagnetic

Alternating field passes through a glass ceramic into the bottom of a cookware that is placed on the cooking surface. The electromagnetic alternating field of the (induction) coil, also called induction heating coil, of the cooking surface creates

cookware induces eddy currents and generates remagnetization losses, which lead to the heating of the bottom of the cookware as long as the ı5 electromagnetic alternating field of the coil exists. In this way, the bottom of the

Cookware can be heated directly without having to heat the contact surface of the cooking zone, as is the case with conventional electric hobs. This can speed up the cooking process and lead to a more energy-efficient cooking process.

In order for the alternating electromagnetic field to heat the base of the cookware as described, it must have at least one layer of a ferromagnetic material, which is usually arranged on the outside, i.e. facing the coil of the cooking area. Rust-proof iron alloys are usually used for this purpose in order to make cookware such as pots and pans suitable for inductive heating.

The generation of the alternating electromagnetic field of the respective cooking area of the

Induction hob can be operated using a suitably large, flat, single-layer coil made of

High frequency wire, which is located at the cooking area directly below the cooking surface or the glass ceramic.

The disadvantage here is that part of the electrical energy used to generate the alternating electromagnetic field is not transferred to the cooking utensils but to the

environment and in particular to the other components of the induction hob and is therefore not used for the cooking process. This reduces the

Energy efficiency of the induction hob. This can also lead to an undesirable

Heating of the components of the induction hob, including the

Can include controls that can be reached and touched by a user.

To avoid or reduce this, it is known to arrange ferritic elements below the induction coil. This allows the area below the

Induction heating device must be kept free of magnetic fields. This can also serve to direct and concentrate the magnetic flux of the electromagnetic field, in particular in the direction of the cooking area or the cooking utensils. Such ferritic elements, also called ferrites, are usually flat and planar or elongated or strip-like. A ferrite element is understood to be an element, in particular a ferrimagnetic element, which is designed to guide the electromagnetic field of the induction coil and/or to adapt it, preferably to increase it.

It is also known to use aluminum sheets for magnetic shielding in such induction heating devices. The aluminum sheets are arranged below the induction coil and below the ferrites and can hold or support them at the same time, which is why these aluminum sheets are also called aluminum support sheets. Depending on their material thickness, the used

Aluminium alloy and the system operating frequency, the aluminium sheets

However, a clearly measurable portion of the energy generated by the induction coils

magnetic field into thermal power loss. This means that effective shielding can be achieved. However, the "intercepted" energy of the electromagnetic field is lost and leads to undesirable heating of the induction heating device and thus also of the induction hob.

If instead an attempt is made to absorb a larger portion of the electromagnetic field by means of the

Ferrites to the cooking utensils and thus from the environment and thus also from the

Shielding of the aluminum sheet, this leads to ferrites, whose

The height is increased in the vertical direction. However, this approach leads to higher induction coils, which also increases the height of the induction device and thus also of the induction hob, which is undesirable.

The invention therefore addresses the problem of improving the energy efficiency of

Induction heating devices, especially for induction hobs. This should be done in particular with the same installation space, especially with the same height. In particular, the heating of the induction heating device should be kept low or reduced. In any case, this should be done as simply, inexpensively and/or compactly as possible. At the very least, an alternative to known

Induction heating devices can be created.

According to the invention, this problem is solved by an induction heating device and by a

Induction hob with the features of the independent claims. Advantageous embodiments and developments of the invention emerge from the following dependent claims.

Thus, the invention relates to an induction heating device for an induction hob with at least one, preferably flat, induction coil, which is designed to inductively heat at least one cooking zone of the induction hob.

The induction heating device is characterized by at least, preferably exactly, one ferrite surface, which is arranged facing away from the cooking area and at least substantially flat and parallel to the induction coil. A ferrite surface can be understood as any at least substantially flat extension of a ferritic material.

The invention is based on the finding that a ferrite surface, which surrounds the ı5 induction coil facing away from the cooking area at least in sections,

Reduction of the energy losses of the electromagnetic field can be achieved. This can increase the energy efficiency of the induction heating device. In other words, by introducing ferritic

Materials below the induction coil significantly reduce power losses

Be fixed in the support plate of the induction heating device.

According to one aspect of the invention, the ferrite surface is completely flat parallel to the

Induction coil arranged. This can be the training or the production as well as the

Simplify the assembly of the ferrite surface and thus make it more cost-effective.

According to a further aspect of the invention, the ferrite surface is arranged substantially flatly parallel to the induction coil and the induction coil comprises at least

Essentially perpendicular to its planar extension, at least in sections, preferably completely. The ferrite surface can thus be designed in a bowl-shaped manner in order to be able to act as described above not only with its essential surfaces but also with its bent-up edge. This can increase the design freedom and improve the effect.

According to a further aspect of the invention, the ferrite surface is designed as a ferrite disk.

A disk is a rigid or fixed flat body that can be handled and assembled by the user. This can be a possible implementation, which can be correspondingly simple and inexpensive. The ferrite disk can also be used to attach itself and other components of the induction heating device.

According to a further aspect of the invention, the ferrite surface is designed as a ferrite foil.

A foil is a relatively thin material that can be shaped or bent and thus brought into shape. In particular, the ferrite foil can be applied to a carrier for stability. This can be a possibility of

Implementation can be simple and cost-effective. The ferrite foil can also be shaped relatively flexibly during assembly.

According to a further aspect of the invention, the ferrite surface is designed as a ferrite coating. The ferrite coating can be applied by means of appropriate methods such as vapor deposition,

Gluing, soldering, welding, rolling, doctoring, painting or sputtering can be used to apply the material to a substrate. This can be another possible implementation.

According to a further aspect of the invention, the ferrite surface is a ferrite-containing

Plastic element. In other words, elements of a ferritic

material into a plastic material and from this mixture the ferrite-containing

Plastic element, for example by means of an injection molding process. This can be another possible implementation.

According to a further aspect of the invention, the ferrite surface has at least one

This can be used to carry out electrical

connections of the induction coil.

According to a further aspect of the invention, the ferrite surface has at least one

Holder and/or at least one receptacle. This can allow, for example, cables and the like to be held or received by the ferrite surface, which can serve for connection and arrangement.

According to a further aspect of the invention, the ferrite surface has at least one

Air passage and/or at least one air duct. This can make it possible to create a particularly targeted or directed ventilation in the area of the ferrite surface.

According to a further aspect of the invention, the ferrite surface, facing away from the induction coil, has at least one electrical and/or electronic component. This can enable the installation of such components on the side of the ferrite surface, so that additional separate holders for this can be dispensed with. This can save effort, costs and in particular installation space. The ferrite surface can also have a shielding effect at the same time.

According to a further aspect of the invention, the ferrite surface is flat parallel to several

Induction coils of a cooking area are arranged. Thus, a single ferrite surface can be used as previously described for several induction coils, which can each form a cooking area or can also form a cooking area together. 5 According to a further aspect of the invention, the ferrite surface is flat parallel to several

Induction coils are arranged, which form a surface cooking field of the induction hob.

Thus, a single ferrite surface can be used on a surface hob as described above.

According to a further aspect of the invention, the induction heating device has at least one ferrite rod, preferably a plurality of ferrite rods, which is arranged flatly parallel to the induction coil between the ferrite surface and the induction coil.

This allows known ferrite rods in combination with the inventive

Ferrite surface can be used.

The present invention also relates to an induction hob with at least one ı5 induction heating device as described above. This makes it possible to create an induction hob in order to have the properties and advantages of at least one

To be able to implement and use the induction heating device as described above.

In other words, it is for inductively operated kitchen appliances such as

Induction hobs are known for the magnetic shielding and mechanical

Construction required aluminum support plates depending on material thickness,

Aluminum alloy and system operating frequency convert a clearly measurable portion of the magnetic field generated by the coils into thermal power dissipation.

Thus, the thermal losses lead to a reduced or limited

Energy efficiency of such inductively operated kitchen appliances. This also means that the

The energy efficiency of such inductively operated kitchen appliances is not sufficient to achieve the required and usually comparatively high energy efficiency labels in markets.

Induction hobs are known to date, which use coils with double the ferrite thickness in height. A second layer of

Ferrites are glued. However, this approach leads to higher coil construction, which means

Induction hobs inevitably involve an increase in the height of the hob.

This would make it impossible to combine the device with cooking appliances. If the coils of the

If induction hobs are left as before, there is a risk of

Induction hobs can therefore no longer serve some markets.

In any case, such induction hobs can also cause problems with thermal

System overload and hot operating areas can occur, which are also caused by the thermal power losses caused by the magnetic fields generated. s Therefore, the invention is intended to be used in inductively operated kitchen appliances and in particular in

Induction hobs can improve energy efficiency, allow the existing coil height to be retained, limit the height of retrofitted series coils, reduce the total height of newly developed coils, reduce the self-heating of the entire hob system, increase the system lifespan, increase the system performance, improve usability and/or retrofit classic

Coil bodies with non-ferritic material in the coil body (e.g. plastic carrier). ı5 According to the invention, this can be achieved at least partially by the flat

A ferrite disc or ferrite foil is inserted under one or each cooking zone, which can significantly improve the energy efficiency of the hob system.

Advantageously, the ferrite discs or ferrite foils are the size of the coil winding and/or have a thickness of 1-2 mm; smaller or larger diameters are also possible.

In flat cooking areas, a ferrite disk or a ferrite foil can also be installed under several coils.

As an alternative to ferrite discs or ferrite foils, the contact area of the

Induction coils coated with ferritic material (e.g. vapor deposition, gluing, soldering,

welding, rolling, doctoring, painting or sputtering) (e.g. flat support plate or

receiving trays).

Advantageously, the ferrite disc or the ferrite foil can have mounting cutouts or

have recesses that fit the coil body used. This allows a

Combination of flat ferrite elements with geometrically differently shaped

Ferrite elements (e.g. ferrite rods, cuboids, circular elements or triangles).

In addition to the two-dimensional flat arrangement, an embodiment can also include a three-dimensionally shaped ferrite element for the purpose of geometric adaptation to different coil configurations (e.g. wok coil, positive connection with

coil elements).

Optionally, mounts and cable routing can be integrated into the ferrite component, which saves the effort for fastening elements that would otherwise be necessary. Plastic injection-molded elements with integrated ferrite materials or special materials such as Magment (cement with ferrite) can be particularly suitable for this.

Optionally, such a ferrite component can also contain recesses or channels for air flow. These can, for example, enable active or passive cooling of the elements and coils as well as electronic components. 100 Optionally, electronic components can also be mounted and operated on the side of the ferrite element facing away from the coils. This arrangement can protect electronic components from stray fields of the induction coil.

Optionally, the ferritic element can be suitably designed (e.g. parabolic) so that stray fields of the coil structure can be diverted in a way that is favorable for the application (e.g.

cookware or micro energy harvesting for e.g. lighting or sensors) or can be diverted away from sensitive areas (e.g. sidebars or user interface).

In any case, in contrast to the previously pursued approach with double

Ferrite rods, according to the invention an influence on the required installation space in the height of, for example, increases of at least 5 mm can be avoided or at least kept to a minimum.

By increasing energy efficiency according to the invention, significant

Energy savings of at least 2% can be achieved. In relation to the high

The service life of such devices can also be described as increased sustainability. Furthermore, the increase in efficiency leads to better ratings for

Energy labels (EEF labels), which give products according to the invention new

Energy efficiency label can open up or secure limited markets.

The lower system losses mean that a longer system lifespan can be expected, since the energy that is no longer converted into waste heat relieves the load on the components. If necessary, components with lower T markings can also be used.

Furthermore, optimized ferrite constructions can reduce the height of the

Induction coils can be reduced. The space freed up can either be used to reduce the installation height of a hob or for future features.

The invention can not only be used for newly developed coils, but can also be retrofitted to existing coils, with minimal change in installation space.

This may even make it possible to use ferrite disks or ferrite foils, as these only have to carry a residual stray field.

As a further effect, the usability can be increased through better system performance and the contact temperatures in the operating area can be reduced, since these can spread to a considerable extent via the aluminum support plate under the operating area.

Several embodiments of the invention are shown purely schematically in the drawings and are described in more detail below. It shows

Figure 1 is a schematic representation of an induction hob;

Figure 2 shows an induction heating device according to the invention according to a first

Example from above;

Figure 3 shows a cross section through the representation of Figure 2; Figure 4 shows an induction heating device according to the invention according to a second

Example from above;

Figure 5 is a cross-section through the representation of Figure 4;

Figure 6 shows an induction heating device according to the invention according to a third

embodiment from above; and

Figure 7 shows a cross section through the representation of Figure 6.

The above figures are considered in Cartesian coordinates. A

Longitudinal direction X, which can also be referred to as depth X or length X.

Perpendicular to the longitudinal direction X there is a transverse direction Y, which can also be referred to as width Y. Perpendicular to both the longitudinal direction X and the transverse direction Y there is a vertical direction Z, which can also be referred to as height Z and corresponds to the direction of gravity. The longitudinal direction X and the transverse direction Y together form the horizontal X, Y, which can also be referred to as the horizontal plane X, Y.

Figure 1 shows a schematic representation of an induction hob 1. The induction hob 1 has a glass ceramic plate 10, which closes the induction hob 1 at the top. An induction heating device 2 is arranged below the glass ceramic plate 10 where a cooking area 11 is provided on the glass ceramic plate 10. The

Induction heating device 12 is electrically conductive with a control unit 13 of the

Induction hob 1 so that the induction heating device 12 of the cooking area 11 can be operated in a controlled or regulated manner by the control unit 13.

In particular, the current intensity, voltage and frequency of an induction coil 22 of the induction heating device 2 of the cooking area 11 can be specified by the control unit 12.

On the cooking area 11, a cooking vessel 3 in the form of a pot 3 is arranged, which has a

Body 30 with a base 31. The base 31 has a layer of a ferromagnetic material. The base 31 faces the induction coil 12 of the cooking area 11 and is arranged above it. The pot 3 is deliberately shown in Figure 1 without contact above the cooking area 11 in order to be able to better distinguish the individual elements of the induction hob 1 and the pot 3 from one another.

Figure 2 shows an induction heating device 2 according to the invention according to a first

embodiment from above. Figure 3 shows a cross section through the representation of the

Figure 2.

According to the invention, the above-mentioned induction heating device 2 has a support body 20, which serves, among other things, for connection to the glass ceramic plate 10. In the vertical ı5 direction Z above, i.e. facing the underside of the glass ceramic plate 10, a

Induction coil 22 or its winding 22 is arranged so that the induction coil 22 is located with its planar extension in the horizontal X, Y. In this case, between the

A ferrite surface 24 is provided between the top side of the support body 20 and the bottom side of the induction coil 22, which also extends flatly in the horizontal X, Y.

The ferrite surface 24 can be designed as a ferrite disk 24, as a ferrite foil 24, as a ferrite coating 24 or as a ferrite-containing plastic element 24.

In any case, the ferritic material of the ferrite surface 24 can shield the electromagnetic field, which is generated by the induction coil 22 during operation, in the vertical direction Z downwards. At the same time, the electromagnetic field can be directed upwards towards the cookware 3, which

Energy efficiency of the induction heating device 2 and thus of the induction hob 1 can be increased.

Figure 4 shows an induction heating device 2 according to the invention according to a second

embodiment from above. Figure 5 shows a cross section through the representation of the

Figure 4. In this case, furthermore, several ferrite rods 23 are aligned in a star shape in the vertical direction Z between the top of the ferrite surface 24 and the bottom of the

Induction coil 22 is arranged. A coil carrier 21, which carries the induction coil 22, is arranged between the ferrite rods 23. This means that additional ferrite rods 23 can be used to align the electromagnetic field.

Figure 6 shows an induction heating device 2 according to the invention according to a third

embodiment from above. Figure 7 shows a cross section through the representation of the

Figure 6. In this case, the edge (not marked) of the ferrite surface 24 in the vertical

bent upwards in the Z direction so that the effect of the ferrite surface 24 can be used in the horizontal X, Y.

List of reference symbols (part of the description)

X longitudinal direction; depth; length

Y transverse direction; width

Z vertical direction; height

XY Horizontal; horizontal plane 1 Induction hob

Glass ceramic plate 11 Cooking area 0 12 Control unit or electronics of the induction hob 1 2 Induction heating device 20 Supporting body 21 Coil carrier 22 Induction coil; winding 23 Ferrite rods 24 Ferrite surface; Ferrite disk; Ferrite foil; Ferrite coating; ferrite-containing

Plastic element 3 Cookware; Pot

Body 31 Floor

Claims (15)

Patent claims 1. Induction heating device (2) for an induction hob (1) with at least one, preferably flat, induction coil (22), which is designed to inductively heat at least one cooking point (11) of the induction hob (1), characterized by at least, preferably exactly, one ferrite surface (24) which is arranged facing away from the cooking point (11) at least substantially flat and parallel to the induction coil (22). 2. Induction heating device (2) according to claim 1, wherein the ferrite surface (24) is arranged completely flat and parallel to the induction coil (22). 3. Induction heating device (2) according to claim 1, wherein the ferrite surface (24) is arranged substantially flatly parallel to the induction coil (22) and surrounds the induction coil (22) at least substantially perpendicular to its flat extension at least in sections, preferably completely. 4. Induction heating device (2) according to one of the preceding claims, wherein the ferrite surface (24) is designed as a ferrite disk (24). 5. Induction heating device (2) according to one of claims 1 to 3, wherein the ferrite surface (24) is designed as a ferrite foil (24). 6. Induction heating device (2) according to one of claims 1 to 3, wherein the ferrite surface (24) is formed as a ferrite coating (24). 7. Induction heating device (2) according to one of claims 1 to 3, wherein the ferrite surface (24) is designed as a ferrite-containing plastic element (24). 8. Induction heating device (2) according to one of the preceding claims, wherein the ferrite surface (24) has at least one through-opening. 9. Induction heating device (2) according to one of the preceding claims, wherein the ferrite surface (24) has at least one holder and/or at least one receptacle. 10. Induction heating device (2) according to one of the preceding claims, wherein the ferrite surface (24) has at least one air passage and/or at least one air guide. 11. Induction heating device (2) according to one of the preceding claims, wherein the ferrite surface (24), facing away from the induction coil (22), has at least one electrical and/or electronic component. 12. Induction heating device (2) according to one of the preceding claims, wherein the ferrite surface (24) is arranged flatly parallel to several induction coils (22) of a cooking point (11). 13. Induction heating device (2) according to one of the preceding claims, wherein the ferrite surface (24) is arranged flatly parallel to a plurality of induction coils (22) which form a surface cooking field of the induction cooking field (1). 14. Induction heating device (2) according to one of the preceding claims, further comprising at least one ferrite rod (23), preferably a plurality of ferrite rods (23), which is arranged flatly parallel to the induction coil (22) between the ferrite surface (24) and the induction coil (22). 15. Induction hob (1) with at least one induction heating device (2) according to one of the preceding claims.