EP3352529B1 - Hotplate - Google Patents

Description

FIELD OF APPLICATION AND STATE OF THE ART

The invention relates to a hob with a hob plate and with at least one induction heating coil arranged thereon or below it, advantageously with several induction heating coils.

From the DE 102015210650 A1 For example, an induction hob is known with a hob plate under which several induction heating coils are arranged. These cover an area which essentially corresponds to that of the hob plate or at least one heating area of the hob plate. It is thus possible for a cooking vessel of any size to be placed on the hob plate at any point and to be heated there with a power that can be specified by an operator.

Furthermore, induction hobs are from the EP 1688018 B1 and the EP 2420105 B1 known with a large number of induction heating coils, for example in a regular arrangement with about 8 x 10 induction heating coils, with which it is also possible to place a cooking vessel at almost any point on a hob and heat it appropriately. The cost of providing such a large number of induction heating coils, which must be individually controllable and at the same time also have to be adjustable in terms of their power, is predictably very large.

From the DE 102012201808 A1 an induction hob is known as a so-called matrix hob with a large number of induction heating coils arranged next to one another under a hob plate. A position and size of cooking vessels that have been set up can be recognized by means of a sensor unit. Adapted to this, the cooking vessels are heated by the corresponding number of covered induction heating coils.

From the EP 2385311 A2 a household workstation such as a hob is known with several induction heating coils underneath. By means of this, a cooking vessel placed above it can be inductively heated. Alternatively, a control unit for the household workstation can be placed over it and inductively supplied with energy.

From the EP 2428733 A1 an induction hob with a plurality of induction heating coils arranged therebelow is known. These can be used alone or in groups to inductively heat a cooking vessel placed above it on a hob plate. For electrical Control of the individual induction heating coils relays are provided for connection to power electronics.

TASK AND SOLUTION

The invention is based on the object of creating a hob mentioned at the beginning with which problems of the prior art can be solved and with which it is in particular possible to bring energy from an induction heating coil not only into a cooking vessel that fits directly above and in terms of size , but also in a cooking vessel which, in particular, is set up on a hob plate a little laterally offset from the coil.

This object is achieved by a hob with the features of claim 1. Advantageous and preferred embodiments of the invention are the subject matter of the further claims and are explained in more detail below. The wording of the claims is made part of the content of the description by express reference.

It is provided that the hob has a hob plate, advantageously a flat hob plate made of hard glass or glass ceramic, on or under which at least one induction heating coil is arranged, advantageously several induction heating coils. The induction heating coils particularly advantageously cover a substantial area of the hob plate or at least the essential area of a heating area of the hob plate on which cooking vessels can be placed for heating. In one embodiment of the invention, the induction heating coils can cover this area directly adjacent to one another except for a small distance. In particular, such a distance can be between 1 mm and 20 mm, particularly advantageously between 5 mm and 15 mm.

According to the invention it is provided that a two-dimensionally extended transmission device is provided under the hob plate or between the at least one induction heating coil and the hob plate. The two-dimensional expansion of the transmission device means that it covers a considerably larger area than a single induction heating coil itself, whereby it at least partially covers it, in particular completely and / or protruding far beyond it. It is particularly advantageous for the transmission device to have a two-dimensional extent which corresponds approximately to that of the hob plate or at least to its heating area as described above. Thus, with its two-dimensional extension, the transmission device can mark or indicate the area in which cooking vessels for heating or cooking can be set up on the hob plate. The transmission device has a large number of resonant circuits which are inductively coupled to one another and which are responsible for the transmission of the energy. Each of the inductively coupled resonant circuits has a transmission coil and a transmission capacitance, so that an LC resonant circuit is formed. In this way, inductive energy generated by an induction coil or induction heating coil for heating a cooking vessel can be inductively transmitted to a cooking vessel very well and largely without losses. For this purpose, this cooking vessel does not have to be directly overlapping with the induction heating coil; rather, partial overlapping may be sufficient or it may also be possible that the cooking vessel does not cover the induction heating coil or its surface at all. A lateral energy transfer can thus take place by means of the transfer device. For this purpose, the transmission coils or the oscillating circuits run essentially in a surface or plane that is parallel to the hob plate. The energy is then transmitted inductively within this area or plane. Alternatively, operating elements and / or displays can be electrically supplied, controlled and / or evaluated by means of the transmission device.

The person skilled in the art can find further information on coupled transmission coils or coupled resonant circuits and energy transmission, inter alia, in the literature on "Magnetoinductive waveguides", such as for example in FIG WO 2012/172371 A1 or the WO 2015/033168 A1 , which are hereby explicitly referred to. Corresponding devices as Metaboards are known from Metaboard Ltd., Oxford, Great Britain, see also http://metaboards.tech/about/products/ . Also on the article " Magneto-inductive waveguide devices "in http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=2196, (Volume: 153, Issue: 2, April 3, 2006), pp. 111 to 121, with print ISSN: 1350-2417 , is explicitly referred to.

In this context one speaks of metamaterials and "wireless power transfer", among other things because of the similarity to phonon models.

In this way, it is possible that a large part of the surface of the hob plate or the heating area does not have to be covered by induction heating coils, so that the structural effort and the effort for corresponding control of a large number of induction heating coils including cabling can be saved. Thus, even a few induction coils can be sufficient in order to be able to achieve a largely arbitrary covering of any position of a cooking vessel on the hob plate with the aid of the transmission device or its oscillating circuits. There is therefore no need to cover the entire heating area with induction heating coils.

In an advantageous embodiment of the invention, it can be possible for individual resonant circuits, in particular the transmission coils or an electrical connection between a transmission coil and a transmission capacitance, to be designed to be switchable. Relays on the one hand and semiconductor switches on the other hand can be used for this purpose. Such switchability can ensure that an oscillating circuit is deactivated, so to speak, and energy is not transferred beyond it. This can ensure a more targeted energy transfer to a place where a cooking vessel placed on the hob has been recognized.

In an embodiment of the invention it can be provided that all resonant circuits or all transmission coils are designed identically. In particular, they are also arranged identically or in each case in the same direction. The electrical properties can also be advantageous the respective resonant circuits and in particular the transmission coils together with the transmission capacities must be the same.

In an embodiment of the invention, the transmission coils can have a largely rectangular shape, in particular be square. In this case, they can only be made somewhat rounded at the corners inside and outside for improved current conduction and easier manufacture.

A transmission coil can have at least one turn which consists of a flat conductor track, in particular a flat copper track. Their width can be between 5 times and 100 times as large as their thickness. A width of the turn can be between 2% and 10% of the diameter of the transmission coil, in particular between 3% and 7%. Thus, a width of the turn is relatively large compared to the diameter, in particular compared to other inductive coils. However, this also serves to be able to keep the height of the transmission device relatively low, so that the overall height required for this in the induction hob below the hob plate does not become too great.

In a further embodiment of the invention, a transmission coil can have several turns, advantageously a maximum of five turns. It is particularly advantageous to have a maximum of three turns in a multi-turn transmission coil. The turns then run in areas which are largely parallel to the area in which the transmission coils run as a whole or which is covered by the transmission device. The turns run helically one above the other. Due to the smallest possible height or thickness of the winding of the transmission coils, even including an insulating material between the turns running one above the other, there is only a relatively small overall height of a transmission coil. By providing more than one turn of at least one of the transmission coils, the efficiency of the energy transmission can be improved or adaptation to different operating frequencies can be facilitated.

In an embodiment of the invention it can be provided that the transmission coils run in a common area and each have a small distance from one another. Gaps between the transmission coils should be a maximum of 5 mm wide, preferably a maximum of 2 mm. In this way, a good flat coverage is possible and, above all, good energy transfer due to the small distance. In this case, the transmission coils can largely cover or form the two-dimensional extent of the transmission device. If the transmission coils consist of bare conductor material as conductor tracks, for example as a copper track, an insulating material can also be provided between them in the lateral direction in order to avoid possible short circuits. This can also be achieved, for example, in that the flat transmission coils are embedded between two layers of plastic material, in particular plastic film. These can be laminated together so that the material of the plastic films is between two adjacent transmission coils, which can be glued or fused to one another to secure the position and for electrical insulation from one another.

The transmission coils can be arranged next to one another in such a way that they largely cover the surface of the transmission device. A transmission coil can therefore have further transmission coils all around or along each straight outer side with a small spacing. Here, neighboring transmission coils could even overlap, for example by running in different planes. An overlap can be between 1% and 10% of the diameter of the transmission coil, in particular between 3% and 7%, or between 1 mm and 20 mm.

As an alternative to a largely covered surface of the transmission device by transmission coils closely spaced on several or all sides, provision can also be made for the transmission coils to be rectangular and only come close to each other in the corner areas and be close to each other, almost to abut each other or even here a little overlap as previously described. Then, so to speak, free areas are formed between the transmission coils or only every second grid space is occupied by a transmission coil in a narrow grid.

A control for the at least one induction coil can be designed for a frequency between 17 kHz and 100 kHz, in particular between 20 kHz and 50 kHz. The energy transmission of the transmission coils then has to be optimized, whereby this can essentially correspond to a usual frequency range for induction hobs. This then makes it possible to fall back on the usual frequencies that are generated and handled in an induction hob, so that the already existing assemblies can be used. In comparison to the aforementioned known prior art, these relatively low frequencies can advantageously be achieved by changing or adapting the capacitance of the L-C oscillating circuits.

In an embodiment of the invention, it is possible that the transmission capacitances of the LC resonant circuits are designed as SMD capacitors, in particular as SMD ceramic capacitors. This makes it possible to improve energy efficiency or transmission efficiency. With SMD capacitors with a small design, it is also possible, above all, to limit the overall height of the transmission device.

In an embodiment of the invention, a transmission device cannot or not only be used to transmit energy to cooking vessels that are offset from an induction heating coil, but also to control displays or optical signaling means, in particular LEDs, which can be arranged at any point under the hob plate. As a type of electrical consumer, it can be connected to a resonant circuit and supplied with energy for lighting or controlled in essentially any known manner. By means of several differently tuned resonant circuits each with at least one LED, the desired resonant circuit of a certain LED can be controlled by appropriate control or feeding of energy into the transmission device, for example by means of an induction heating coil or a separate excitation coil, and by tuning the frequency so that it lights up . A resonant circuit with an LED connected or coupled to it can have a specific resonance frequency. A specific LED can then be selectively controlled by controlling the transmission device at variable frequencies.

In a further embodiment of the invention, it is possible for a sensor to be connected to at least one transmission coil or to at least one resonant circuit. This is advantageously a capacitive touch sensor, as is known, for example, for operating elements on a hob plate, see, for example, FIG EP 859467 A2 . With such sensors, in particular capacitive touch sensors or also temperature sensors with a temperature-dependent resistance value, resonance frequencies of an oscillating circuit can be influenced or detuned differently. This can then be detected on an energy coupling or activation of the transmission device, in particular on an induction heating coil or an aforementioned excitation coil. In this way, the temperature can also be measured over an area or several touch sensors distributed over the hob plate can be queried or operated as operating elements.

When a cooking vessel is placed on the hob, the oscillating circuit is detuned or the resulting inductive coupling changes the effective resistance. As a result, the power is tapped at the place where this detuning takes place. For example, the effective resistance of an induction heating coil changes when a cooking vessel is put on from 0.025 ohms to approx. 5 ohms due to the inductive coupling. In this way, power can be introduced into the cooking vessel that has been set up, advantageously in the case of an induction hob.

In the context of the invention, it should also be possible for any hob to be provided with such a transmission device under a hob plate, for example a gas hob. Then at least one previously described excitation coil is necessary for the transmission device. The transmission device should then not be provided here for inductive energy transmission, but rather for control and / or evaluation for the aforementioned optical signaling means or LEDs or touch sensors of operating elements. Then a separate excitation coil has to be provided for the transmission device. The transmission device then does not serve to transmit inductive energy to a cooking vessel placed on the hob plate, for which purpose a gas burner would then be provided. Rather, different, distributed temperature sensors and / or operating elements with capacitive touch sensors or the like are intended. can be evaluated.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

einen Schnitt durch ein erfindungsgemäßes Kochfeld als Induktionskochfeld mit Kochfeldplatte und Induktionsheizspulen darunter, wobei dazwischen eine Übertragungsvorrichtung angeordnet ist,

Fig. 2

eine Draufsicht auf das Induktionskochfeld aus Fig. 1 mit gestrichelt dargestellten Induktionsheizspulen und einer strichpunktiert dargestellten Übertragungsvorrichtung,

Fig. 3

eine Draufsicht auf die Übertragungsvorrichtung mit rechteckigen einwindigen Übertragungsspulen und Übertragungskapazitäten als L-C-Schwingkreis,

Fig. 4

einen einzelnen L-C-Schwingkreis mit einer einwindigen Übertragungsspule und einem Kondensator als Übertragungskapazität und

Fig. 5 und 6

Abwandlungen der Darstellung aus Fig. 3 mit unterschiedlichen Anordnungen von Übertragungsspulen.

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

Fig. 1

a section through a hob according to the invention as an induction hob with hob plate and induction heating coils underneath, with a transmission device arranged in between,

Fig. 2

a top view of the induction hob Fig. 1 with induction heating coils shown in dashed lines and a transmission device shown in dash-dotted lines,

Fig. 3

a top view of the transmission device with rectangular single-turn transmission coils and transmission capacities as an LC resonant circuit,

Fig. 4

a single LC resonant circuit with a single-turn transmission coil and a capacitor as transmission capacity and

Figures 5 and 6

Modifications of the representation Fig. 3 with different arrangements of transmission coils.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the Fig. 1 a hob according to the invention is shown in simplified form as an induction hob 11 in a side section, the induction hob 11 having a hob plate 13 corresponding to a conventional design, on the underside of which a flat housing 15 is arranged. Flat induction heating coils 17 are arranged in the housing 15 as shown in FIG Fig. 2 , so with an essentially rectangular basic shape and a small distance from one another. This is for example from the DE 102014224051 A1 known, to which reference is made explicitly in this regard. The induction heating coils 17 rest on a support plate 18. Under the support plate 18, the housing 15 has schematically illustrated units for a control 19 and a power supply 20. The control 19 also contains control intelligence for the induction hob 11. In addition, the top view of the Fig. 2 recognizable display 23 and control elements 25 are controlled and evaluated. This is known per se from the prior art. From the Fig. 2 Additional control elements 26 shown in the rear area can be seen, which are advantageously designed, similar to the control elements 25, as capacitive touch switches with capacitive touch sensors. Likewise, round lights 27 shown in dotted lines are provided between the two rear rows of induction heating coils 17. With these lights 27, their activation status can be displayed, alternatively also, for example, a residual heat indicator or the like. will be realized.

In the front area of the induction hob 11 on the display 23 and the operating elements 25, no induction heating coil 17 is provided, but only to the left and right of it. This can of course also be provided differently; many possibilities for a corresponding arrangement are known and conceivable from the prior art.

A transmission device 28 according to the invention is shown in FIG Fig. 3 shown in plan view. It is like the sectional view of the Fig. 1 already shows very flat and has, for example, a thin carrier 29, which can even be formed like a film. The LC oscillating circuits 30 can be applied directly to this carrier 29, even as a film, either by gluing on or by direct coating or also printing. Appropriate processes are familiar to the person skilled in the art and do not present any problems whatsoever. It can be seen that the LC resonant circuits 30 each have a transmission coil 32 and a transmission capacity 34. When displaying the Fig. 3 the carrier 29 is to be provided with such LC oscillating circuits 30 largely over the entire surface, in particular except for the area of the display 23 and the front operating elements 25. For the sake of clarity, however, not all are shown. In the front area of the induction hob 11 on the display 23 and the operating elements 25, the LC oscillating circuits 30 can also be saved.

All L-C resonant circuits 30 are advantageously designed identically. As can be seen, they are each aligned or arranged in the same way. This does not necessarily have to be the case, but has proven to be advantageous for good energy transmission within the transmission device.

The distance between adjacent LC resonant circuits 30 or, above all, the transmission coils 32 can be relatively small and, for example, between 1 mm and 15 mm, advantageously between 2 mm and 10 mm. This applies both to transmission coils 32 arranged laterally next to one another and to those arranged one behind the other. The distance should be so small that they are inductively coupled to one another in every direction in any case. In one embodiment of the invention, it is even conceivable that different transmission coils 32, in particular adjacent ones, run in different planes and even overlap in plan view, see in this regard Fig. 5 .

In the Fig. 4 an LC resonant circuit 30 'is shown in enlargement, as it could be designed in practice. It has a transmission coil 32 'which consists of a single turn, the coil ends 33' of which are not completely closed or are at a small distance from one another. A transmission capacity 34 'is connected to these coil ends 33', this transmission capacity advantageously being a discrete component, for example an SMD component. The capacity can be in the range of <1 µF.

An inductance of a single-turn transmission coil 32 'can be in the range of approximately 1 μH. A capacity of the transmission capacity 34 'can be slightly above 30 μF for a desired frequency of approximately 20 kHz and approximately 15 μF for a frequency of 30 kHz. The capacities C are then to be selected accordingly.

An increase in the number of turns of a transmission coil 32 has a significant effect on its inductance, as can easily be foreseen. With each additional turn, of course, the manufacturing expense for the transmission coils 32 and thus also for the transmission device 28 increases.

As explained at the outset, the transfer device 28 can be used to transfer energy from one of the induction heating coils 17 to another. For example, not all induction heating coils 17 would have to be connected to the control 19 and / or power supply 20. The transmission device 28 could transmit the energy precisely in induction heating coils 17, so to speak, somewhat further away therefrom. This could save wiring effort. Furthermore, the induction heating coils 17 could also be saved in some areas of the induction hob 11 or have a greater distance from one another, so that there the transmission coils 32 at least partially take over the energy transmission into an installed cooking vessel.

In a further embodiment of the invention, it is possible for energy to be transmitted to a lighting system 27. This can have an LED with an oscillating circuit that is tuned to a specific resonance frequency. With the transmission device 28, energy can then be coupled in with a specific frequency which, due to the special resonance frequency of the lighting 27, only causes it to light up, but not other provided lighting devices with a resonance frequency different therefrom. Both types of energy transfer take place via the resonant circuit detuning described above.

Additional operating elements 26 can be activated in a similar manner. Especially when these have capacitive touch sensors, which change their capacitance when a finger is placed on the top of the hob plate 13 and thus detune an oscillating circuit, various feedbacks can be used to determine which of the additional operating elements 26 has been operated and thus detuned. For this, too, there is no need for complex cabling to the respective locations of the additional operating elements 26, which, due to their arrangement in the heating area of the induction hob 11, could cause additional problems due to excessively high temperatures. This energy transfer to lighting 27 as a display and / or the control of additional operating elements 26 can also be used in any cooktop, for example with radiant heating elements or gas burners.

The Fig. 5 shows a simplified representation based on the Figures 3 and 4 , as in the case of a transmission device 128, adjacent transmission coils 132 of LC resonant circuits 130 overlap one another in a simple manner. For this purpose, these are alternately arranged on an upper side and a lower side of the carrier 129, specifically the LC resonant circuits 130 shown in solid lines on an upper side and the LC resonant circuits 130 shown in dashed lines on a lower side. An overlap can then be in the range from 0.5 cm to 2 cm if the transmission coils 132 have a length and / or width in the range between 10 cm and 30 cm, in particular between 15 cm and 25 cm.

The Fig. 6 shows in a simplified representation how in a transmission device 228 LC resonant circuits 230 or especially the transmission coils 232 are arranged on the carrier 229 of the transmission device 228 in such a way that, so to speak, every second field in a row and in a column is not occupied. Thus, adjacent transmission coils 232 only approach one another in their corner regions or run close to one another, which still results in a sufficient inductive coupling for the transmission device 228.

Claims (14)

1. Cooktop (11) with a cooktop plate (13) and at least one induction heating coil (17) arranged underneath, characterized in that:

   - a transmission device (28, 128, 228) of superficial extension is provided underneath the cooktop plate (13), which transmission device is arranged for energy transmission in a sideways direction,

   - the transmission device (28, 128, 228) includes a plurality of resonant circuits (30, 30', 130, 230) inductively coupled to each other, each with a transmission coil (32, 32', 132, 232) and a transmission capacity (34, 34', 134, 234) as a resonant LC circuit,

   - the transmission coils (32, 32', 132, 232) extend essentially in an area which is parallel to the cooktop plate (13),

   - the transmission coils (32, 32', 132, 232) are different from the at least one induction heating coil (17) and disposed above.
2. Cooktop according to claim 1, characterized in that all of the transmission coils (32, 32', 132, 232) are of identical design.
3. Cooktop according to claim 1 or 2, characterized in that the transmission coils (32, 32', 132, 232) have a rectangular shape, in particular are square-shaped.
4. Cooktop according to any of the preceding claims, characterized in that a transmission coil (32, 32', 132, 232) has at least one winding made of a flat copper strip, preferably having a width between 2% and 10%, in particular between 3% and 7%, of the diameter of the transmission coil.
5. Cooktop according to any of the preceding claims, characterized in that at least one transmission coil (32, 32', 132, 232) has multiple windings, preferably a maximum of five windings, wherein the windings extend in areas parallel to the area in which the transmission coils extend.
6. Cooktop according to any of the preceding claims, characterized in that the transmission coils (32, 32', 132, 232) extending in an area each have a short distance to each other such that the gaps between the transmission coils have a width of at maximum 5 mm, preferably at maximum 2 mm.
7. Cooktop according to claim 6, characterized in that the transmission coils (32, 32', 132, 232) largely cover the superficial extension of the transmission device (28, 128, 228).
8. Cooktop according to any of claims 1 to 5, characterized in that adjacent transmission coils (132) overlap, wherein preferably they extend in different planes, wherein in particular overlapping amounts to between 1% and 10% of the diameter of the transmission coil (132).
9. Cooktop according to any of claims 1 to 5, characterized in that the transmission coils (232) are rectangular and come close to each other merely in corner segments and have a short distance to each other, preferably between 1% and 10% of the diameter of the transmission coil (232), almost contact one another or here also overlap somewhat, so that free zones are formed between the transmission coils, wherein in particular in a tight grid only very second grid position is occupied by a transmission coil (232).
10. Cooktop according to any of the preceding claims, characterized in that the transmission coils (32, 32', 132, 232) are applied to a film-type carrier (29, 129, 229).
11. Cooktop according to any of the preceding claims, characterized in that the cooktop is an induction cooktop (11) with induction heating coils (17) and controlling for the induction heating coils is configured for their activation with a frequency between 17 kHz and 100 kHz.
12. Cooktop according to any of the preceding claims, characterized in that the transmission capacities (34, 34', 134, 234) of the resonant LC circuits (30, 30', 130, 230) are embodied in SMD capacitors.
13. Cooktop according to any of the preceding claims, characterized in that an LED is coupled or connected to a transmission coil (32, 32', 132, 232) to supply energy to the latter.
14. Cooktop according to any of the preceding claims, characterized in that a sensor, in particular a capacitive touch sensor, is coupled or connected to a transmission coil (32, 32', 132, 232) for an operating element (25, 26) on the cooktop plate (13).

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