Cooking appliance

Abstract

A mobile cooking appliance (101, 101') has a radiant heater (21) and an induction coil (19) in its housing (11), wherein control electronics are provided with which said heating elements (19, 21) can be controlled either in an infrared radiation mode (111) or in an induction mode (110). In this case, after the conventional use of the mobile cooking appliance as a hotplate, the cooking appliance can be used for baking with an overhead arrangement, so that this function is combined with the rapid heating with eddy currents (16, 116) via bottom heat.

Description

TECHNICAL FIELD

[0001] The present invention relates to a mobile cooking appliance with a radiant heater. STATE OF THE ART

[0002] Every electric cooker uses heating elements to heat the cookware placed on top. Such cookware is usually a pan or pot. The heating elements of the cookware are typically designed using one of the following three technologies: Induction coil, radiant heater (also known colloquially as ceramic hob), or cast iron plate

[0003] Radiant heaters are usually made of stainless steel coils that are heated to a glowing temperature; less frequently, halogen heaters are used instead.

[0004] Electric cookers can be permanently installed or designed as mobile cooking units. US Pat. No. 6,201,217 discloses a mobile cooking appliance that has heating elements above the food in addition to heating elements below it.

[0005] Another such cooking stove is known from EP 4 053 454 A1, in which a cooking utensil can be moved on a drawer into a cooking chamber, which has heating elements below the drawer and overhead heating elements on the ceiling of the cooking chamber. The heating elements below the drawer can have induction coils to inductively heat the cooking utensil. Radiation devices are provided for the overhead heating elements, in particular, in which the power is emitted primarily by infrared radiators in the form of heat radiation.

[0006] JP 2004 / 192980 solves the technical problem of making, for example, an aluminum pot or an earthenware pot, neither of which is suitable for induction cooking, usable for an induction cooker. For this purpose, an induction cooking appliance is provided with a plate made of a far-infrared radiator on the surface of a heating plate, which generates heat through electromagnetic induction. Because the cooking appliance thus has a heat-generating plate made of the infrared radiator, the heat from the induction heater is transferred to the cookware, and the heat from the infrared radiation radiated by the infrared radiator heated by the induction heater is also transferred to the cookware when the cookware is placed on the infrared radiator for direct heating. This combined effect makes it possible to cook in a short time.

[0007] The applicant markets the "Navigenio" as a mobile cooking appliance equipped with a radiant heater. The instruction manual for the C0020 model states that the cooking appliance can be placed "overhead" on an open 20 or 24 cm pot to use the mobile cooking appliance for baking. PRESENTATION OF THE INVENTION

[0008] Based on this prior art, the object of the invention is to provide a mobile cooking appliance which, when used as a mobile cooking area, has a better and, in particular, more flexible heating performance.

[0009] This object is achieved according to the invention in that the mobile cooking appliance also has an induction heater in addition to the radiant heater.

[0010] The mobile cooking appliance then has the features of claim 1. It comprises a radiant heater and an induction coil in its housing, with control electronics provided for controlling said heating elements either in an infrared radiation mode or in an induction mode. After the usual use of the mobile cooking appliance as a hotplate, the cooking appliance can be used for baking in an overhead position, thus combining this function with the rapid heating with eddy currents via bottom heat.

[0011] It is interesting to provide a coil arrangement comprising at least one hybrid coil, wherein the control electronics are configured so that the hybrid coil can be controlled as a radiant heater or as an induction coil. The hybrid coil has sufficient resistance to emit heat radiation and, at the same time, is designed to generate an inductive heating output of at least 20%, preferably 50%, when an induction-capable cookware item is placed on the cooking surface of the cooking appliance.

[0012] The coil arrangement can also comprise at least one heating coil and a separate induction coil, with the control electronics configured to control either the heating coil(s) as radiant heaters or the induction coil(s) in induction mode. For this purpose, the control electronics detects the placement of induction-compatible cookware.

[0013] The heating coil(s) can then be arranged between the turns of the induction coils, for example arranged substantially concentrically to one another.

[0014] The heating coil(s) can also be arranged above or below the induction coils in a different plane, which makes it possible to cover the entire cooking area.

[0015] The induction coils can be covered with one or more ferrite elements on the side of the housing facing away from the cookware in order to keep the potentially eddy current active area away from parts outside the housing / cookware (e.g. table top).

[0016] The control electronics can include a 3D position sensor that can determine whether the cooking appliance is positioned overhead. This is equivalent to determining that induction heating is not necessary / possible.

[0017] Further embodiments are specified in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Preferred embodiments of the invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. In the drawings: Fig. 1A shows a schematic cross-sectional sketch of a mobile cooking appliance mounted on a base plate according to an embodiment of the invention with a cooking utensil mounted thereon in induction heating mode; Fig. 1B shows a schematic cross-sectional sketch of the cooking appliance according to Fig. 1A with a cookware placed on top and an overhead cooking appliance in radiant heating mode; Fig. 1C shows a schematic cross-sectional sketch of the overhead cooking appliance according to Fig. 1B in radiant heating mode; Fig. 1D shows a schematic cross-sectional sketch of the cooking appliance according to Fig. 1A with a non-induction-compatible cookware placed on top in radiant heating mode; Fig. 2 shows a schematic cross-sectional sketch of a first mobile cooking appliance placed on a base plate according to a further embodiment of the invention with a cookware placed on top and a second mobile cooking appliance inserted overhead; Fig. 3 shows a schematic cross-sectional sketch of a first mobile cooking appliance placed on a base plate according to a further embodiment of the invention with a cookware placed on top and a second mobile cooking appliance inserted overhead; Fig. 4 shows a schematic plan view of a heating coil, as shown in the cross-sectional view in Fig. 1A is installed; Fig. 5 shows a schematic plan view of two heating coils as shown in the cross-sectional view in Fig. 2 are installed; Fig. 6 shows a block diagram of a cooking appliance according to one of the embodiments of the invention; and Fig. 7 shows a hybrid coil as shown in the cross-sectional view in Fig. 2 or Fig. 3 is installed. DESCRIPTION OF PREFERRED EMBODIMENTS

[0019] The Fig. 1A shows a schematic cross-sectional sketch of a mobile cooking appliance 100 placed on a base plate 6 according to a first embodiment of the invention with a cooking utensil 3 placed thereon in induction heating mode. Fig. 1B shows a schematic cross-sectional sketch of the same cooking appliance 100 according to Fig. 1A with a cookware 3 placed on top and an overhead cooking appliance 100' in radiant heating mode, also called ohmic baking mode. The cookware advantageously has a rim 5 and can be designed with a liquid 1 as the medium to be heated.

[0020] The present drawings with the following description will show a total of three versions of the cooking appliance, which will receive the reference numerals 100, 101 and 102. If these cooking appliances are used as overhead cooking appliances, the reference numerals of these appliances will receive an apostrophe, here in Fig. 1B i.e., 100'. Furthermore, arrows pointing to these cooking appliances indicate the type of heating, i.e., whether they operate primarily as induction heating (arrow 110) or as radiant heating (arrow 111).

[0021] A mobile cooking appliance 100 is placed on a base plate 6, which may in particular be a flat tabletop. The mobile cooking appliance 100 has a housing 11, which is covered by a glass ceramic plate (not shown in the drawing).

[0022] The cover of the housing 11 is selected so that a heating coil arrangement 20 provided in the cooking appliance 100 can introduce its heat radiation 17, indicated by arrows, through this cover into the plate 4 of the cooking utensil 3 in the heat radiation heating mode. The individual hybrid heating coils 12 can and are shown in the drawing of the Fig. 1A operated as induction coils and, together with the cookware base 4 made of magnetizable material, heat this base 4 via an alternating electromagnetic field. Reference numeral 16 denotes the eddy currents forming in the base of the cooking appliance 100, whereby circles have been used in contrast to the physical hybrid coils 12 visualized by hexagons. The eddy currents are essentially effective through the area visualized by the border 116. In induction heating mode 110, the hybrid heating coil 12 operates without glowing and has an inductive component of the heating output of at least (advantageously) 20%, better 50%. This is ensured in particular by the design of the hybrid coil 12 and the frequency of the field. Ferrite surfaces 15 are provided below the hybrid coils 12 in the base of the cooking appliance 10.The eddy currents are each limited to the area of ​​a magnetic field 14 defined by the dashed box 116, which heats the base 4 of the cookware, allowing it to subsequently release the energy as thermal radiation 17. The coil arrangement 20 is shown here with three windings, with the crosses and dots indicating the current direction.

[0023] The Fig. 1B shows next to the cooking appliance 100 from Fig. 1A also one, possibly additional, cooking appliance 100' in overhead mode. Here the heating works by heat radiation 117, while the heating from below as in Fig. 1A is designed. The same hybrid heating coils 12 that did not glow during operation as an induction coil now glow as radiant heaters and thus initiate heat radiation according to the arrows 117. The function of the additional cooking appliance 100' is therefore designated by the arrow as radiant heating. Instead of a double heating system with two appliances, the same cooking appliance 100 can of course be used as an overhead cooking appliance 100' after preheating the base 4 of the cooking utensil 3. Identical features are identified by the same reference numerals in all figures, and similar features are identified by similar reference numerals. The border 116' shows the eddy current region that is not effective here, since on the other side of the hybrid coils 12 with respect to the ferrites 15 there is only the cooking chamber 2.

[0024] The Fig. 1C shows a schematic cross-sectional sketch of the cooking appliance 100' according to Fig. 1B as an overhead cooking appliance in radiant heating mode. This allows for faster heating of induction-compatible cookware 3 by using an insert such as in Fig. 1A This can be achieved by placing the same cooking appliance 100 in overhead operation on the edge 5 of the cookware 3 and creating a baking effect through heat radiation 111, while a previously heated base plate 4 also heats the food from below. In particular, the cookware can then be placed on a thermally insulating plate 7.

[0025] The Fig. 1D again shows the cooking appliance 100 with hybrid coils 12. The hybrid coils 12 glow as radiant heaters and thus initiate heat radiation in their primary function as radiant heaters 111 according to arrows 117, since the cookware 2 is not suitable for induction heating. Here, too, the cookware 2 operates without further modifications. Reference numeral 116' again designates the potential (ineffective) eddy current region.

[0026] The Fig. 2 shows a schematic cross-sectional sketch of a first mobile cooking appliance 101 placed on a base plate 6 according to a further embodiment of the invention with a cooking utensil 3 placed thereon and a second mobile cooking appliance 101' placed overhead according to this further embodiment.

[0027] On a base plate 6, which can in particular be a flat tabletop, a first of two mobile cooking appliances 101 is placed. The mobile cooking appliance 101 has a housing 11, which is covered by a glass ceramic plate not shown in the drawing.

[0028] The cover of the housing 11 is selected such that a radiant heater (including halogen) 21 provided in the cooking appliance 101 can introduce its heat radiation 17, indicated by arrows, through this cover into the plate 4 of the cookware 6, which thus also heats the food to be cooked, identified by reference number 1, in the cooking chamber 2 of the cookware 3. These radiant heaters 21 operate according to the principle of heat radiation. Any type of cookware 3 can be heated with heat radiation, regardless of its material, and the cooktop heats up naturally. The radiant heater arrangement 20 consists in particular of heating coils embedded beneath the glass ceramic plate. Two heating coils 21 are shown here, one on the left and one on the right, which act on the cookware 6 via vertical heat radiation, indicated by the arrows 17, and also via heat conduction into the housing cover 11, i.e., for example, the glass ceramic plate.The heating coils 21 are arranged in particular in a ring shape, possibly in spirals with more than the two loops shown here.

[0029] In addition, the cooking appliance 101 has induction coils 19, which are arranged around the heating coils 21 here and, together with the cookware base 4 made of magnetizable material or via a ferrite surface 15 behind the coils, heat this base 4 via an alternating electromagnetic field, which is again indicated by the dashed area of ​​the eddy current visualization 116. The eddy currents forming in the base 4 are designated by reference numeral 16. The outer heating coils can be designed as pure induction coils 19, thus achieving a separation of the two functions of the induction heater 110 and the function as a radiant heater 111.

[0030] In the illustrated embodiment, ring-shaped heating zones are provided for the heating functions 110 and 111, an outer and an inner heating zone, with the heating coils of the radiant heaters being provided as the inner zone. These heating zones can also be arranged the other way around, with the pure induction coils 19 on the inside and the coils 21 operating solely as radiant heaters on the outside. As already explained in connection with Fig. 1 can the Fig. 2 can also be regarded as a representation of two successive heating processes, namely a first heating of the base plate 4 of the cooking utensil 3 by the cooking appliance 101 and then the overhead use of the same cooking appliance as an overhead cooking appliance 101'.

[0031] The Fig. 3 shows a schematic cross-sectional sketch of a first mobile cooking appliance 102 mounted on a base plate according to a further exemplary embodiment of the invention, with a cooking utensil 3 mounted thereon and a second mobile cooking appliance 102' inserted overhead. These further exemplary embodiments have heating zones arranged one above the other perpendicular to the base plate. In addition to induction coils 19 in front of a ferrite surface, a further coil with the arrangement according to reference numeral 21 is also provided. These induction coils 19 in the dashed boxes 116 represent an induction heater, while the heating coils 21 arranged above them are designed to heat directly via thermal conduction.

[0032] Thus, the cooking appliance 100, 101, or 102 is versatile, as a cooking surface that heats up faster than other cooking appliances if the cookware 3 is induction-compatible, or via the heating coils 12 of the radiant heaters 21 if the cookware is not induction-compatible. The stacked coils 19 and 21 allow for a larger surface area for the heating coils.

[0033] What is essential is the ability to first heat the bottom of a cookware 3, particularly an induction-compatible cookware 3, using the cooking appliance 100, 101, or 102, and then to place this cooking appliance 100, 101, or 102 as an overhead cooking appliance 100', 101', or 102', respectively, on the edge 8 of the cookware 3 with the housing cover 11 facing downwards. This cooking appliance can then be used for baking, gratinating, or for simultaneous heating. When the heating coils 12, 19, 21 of the radiant heaters of the cooking appliance 100', 101', or 102' are switched on, the appliance heats the cooking chamber 2 of the cookware 3 with top heat, indicated by arrows 117. The same applies to the dual-function coils 20, which can be controlled as heating coils for a heat radiation function 111 and as induction coils. These are hybrid heating coils with control electronics that control both of these modes.

[0034] With separate coils for the induction heater 110 and the radiant heater 111, a coil with thick-diameter wires is used as a helix for low resistance, resulting in minimal induction. The conductor material used is a sufficiently high-resistance conductor to limit the current. The resistance defined by the resistance R and the LC element in a coil is small without the effect of annealing, while the resistance R becomes large during annealing. Currently, the cookware 3 and its base 4 are usually made of a commercially available steel and NiCu alloy.

[0035] The cooking utensil 3 can also stand on a stove, so that there is a heating effect from below and separately from this on the cooking space formed by the pot and the cooking appliance 100', 101' or 102' forming a lid, from above.

[0036] The combined use of radiant heaters of the cooking appliance 100' overhead (where no induction effect is possible) and the use of induction coils 19 from below when used as a cooking appliance 100 results in very good heating efficiency for the bottom heat. Only minimal power loss is generated in the cooking surface, allowing for a rapid heating time of the food being cooked and enabling finely graduated and rapid regulation of the heating output.

[0037] The Fig. 4 shows a schematic plan view of a heating coil as shown in the cross-sectional view in Fig. 1A It has two feed points 13, one at the outer edge of the spiral and one at the inner edge. Six ferrite plates are provided radially here. A real heating coil has far more than three turns, in particular between 10 and 20 or between 10 and 30 turns. The provision of six ferrites 15, on the other hand, often represents an optimum balance between effectiveness and manufacturing costs. However, 10 ferrites 15 or a single, disc-shaped ferrite can also be provided.

[0038] The Fig. 5 shows a schematic plan view of two heating coils as shown in the cross-sectional view of the cooking appliance 101 in Fig. 2 can be installed. Feed points 13 of the outer heating coil and feed points 22 for an inner heating coil 21 are provided. Since only the outer heating coil is intended to function as an induction coil, the six ferrites shown here are arranged so as to only cover the coils of the outer heating coil.

[0039] The Fig. 6 shows a block diagram of the control electronics 50 of a cooking appliance 100, 101, or 102 according to one of the embodiments of the invention. The power supply has an electrical input socket 30 with conventional connection values. This is connected to an AC-AC converter 32 via an electrical access line 31. As an output, the heating coils of various embodiments of cooking appliances and positions (bottom heat or overhead arrangement) 104 can be controlled via the power electronics 32 via the electrical connection 33, in particular the embodiments of the cooking appliances 100, 101, or 102 according to Fig. 1A , Fig. 1C and Fig. 1D .

[0040] The actual power value 36, along with optional actual values ​​(ohmic resistance and / or leakage inductance), is fed to a control circuit for adaptive control. The actual value 36 is compared with a setpoint 35 supplied by a power selector switch 34 in a comparison device 37 to then provide a control output 43 as a control input 38 for an adaptive control element 42, which then supplies the control signal for the electrical connection 33. In addition to the further actual values ​​39, an optional position signal 41 is also supplied to the adaptive control element 42. This position signal is determined by a 3D position sensor 40, which can be used to determine which regime is being controlled, i.e., bottom heating or overhead heating. For this purpose, the magnetic field strength can be used to determine whether the bottom heating is primarily based on induction heating or radiant heating.

[0041] With this control, all types of heating coils can be controlled, as shown by three examples in the lower part of the Fig. 6 is shown schematically.

[0042] Fig. 7 finally shows another heating coil, as shown in the cross-sectional view in Fig. 1A can be installed. Feed points 13 of the outer heating coil and feed points 22 for an inner heating coil 21 are provided. Since only the outer heating coil is intended to function as an induction coil, the six ferrites shown here are arranged so as to only cover the coils of the outer heating coil. LIST OF REFERENCE SYMBOLS

[0043] 1Food 2Cooking chamber 3Cookware 4Base plate of the cookware 5Top edge of the cookware 6Base plate (e.g. table) 7Thermal insulation 11Housing 12Hybrid coil 13Feed point hybrid coil 14Magnetic field 15Ferrite (soft magnetic) 16Eddy current visualization 17Heat radiation 19Induction coil 20Heating coil arrangement 21Heating coil 22Feed point heating coil 30Electrical input socket 31Electrical access line 32AC-AC converter, power electronics / converter hybrid coil 33Electr.Connection 34Power selector switch 35Power setpoint 36Power actual value 37Comparator 38Control input variable 39Optional actual values ​​for adaptive control, effective resistance (R) and / or leakage inductance (L) 403D Position sensor 41Optional position signal 42Adaptive control element 43Control output manipulated variable (switching frequency) 44Converter, control and regulation electronics 50Control electronics 100Cooking appliance (first version) 101Cooking appliance (second version) 102Cooking appliance (third version) 100Cooking appliance in overhead mode (first version) 101Cooking appliance in overhead mode (second version) 102Cooking appliance in overhead mode (third version) 104Cooking appliance (symbolic representation) 110Primary function as induction heater 111Primary Function as thermal radiation heating 116effective eddy current area 116potential (ineffective) eddy current area 117thermal radiation 120cooking appliance 121heating coil 122feed point heating coil.

Claims

1. Mobile cooking appliance (100, 101, 102; 100', 101', 102') with a radiant heater (21) and control electronics (50) controlling the same, characterized in that the mobile cooking appliance also has, in addition to the radiant heater (21), an induction coil (19, 12) which can be controlled by the control electronics (50).

2. Mobile cooking appliance according to claim 1, characterized in that the radiant heater comprises a coil arrangement (20) with at least one hybrid coil (12), wherein the control electronics (50) are configured such that the hybrid coil (12) can be controlled as a radiant heater (21) or as an induction coil (12).

3. Mobile cooking appliance according to claim 1, characterized in thatthe mobile cooking appliance comprises in the housing (11) a coil arrangement (20) which has at least one heating coil (21) and a separate induction coil (19), wherein the control electronics (50) are configured to control either the heating coil(s) (21) as a radiant heater or the induction coil(s) (19) in induction mode.

4. Mobile cooking appliance according to claim 3, characterized in that the heating coil(s) (21) is or are arranged between the turns of the induction coils (19).

5. Mobile cooking appliance according to claim 3, characterized in that the heating coil(s) (21) is or are arranged above or below the induction coils (19).

6. Mobile cooking appliance according to one of claims 1 to 5, characterized in that the induction coils (19) on the side of the housing (11) facing away from the cooking utensil (3) are covered with one or more ferrite elements.

7. Mobile cooking appliance according to one of claims 1 to 6, characterized in thatthe control electronics (50) are designed to control the induction or hybrid coils (12, 21) in the induction heating mode (110) without glowing and with an inductive component of the heating power of at least 20%.

8. Mobile cooking appliance according to claim 7, characterized in that the inductive component of the heating output is at least 50%.

9. Mobile cooking appliance according to one of claims 1 to 8, characterized in that the control electronics (50) comprises a 3D position sensor (41) with which it can be determined whether the cooking appliance is arranged overhead.

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