Patent Publication Number: US-2021195701-A1

Title: Induction furnace device

Description:
The invention relates to an induction oven device according to the preamble of claim  1  and to a method for producing an induction oven device according to the preamble of claim  13 . 
     Cooktops are known from the prior art, which have heating units with induction coils which are fastened to a substrate unit. The substrate unit is provided to hold the induction coils in relation to a cooktop plate and to define a course of a conductor of the induction coil. Various methods of fastening the induction coils to the substrate unit are known, for example it is known to use clamps, screws, flaps, adhesives and plastic profiles. These known solutions, however, are only suitable for operating temperature of over 500° C. to a limited extent, as the use of special heat-resistant materials is expensive and established fixing methods are not designed for a thermal expansion of the induction coil. 
     The object of the invention consists in particular in providing a generic device with improved properties with respect to robustness and cost-effectiveness. The object is achieved according to the invention by the features of claims  1  and  13 , while advantageous embodiments and developments of the invention can be taken from the subclaims. 
     The invention is based on an induction oven device with at least one heating unit, which has at least one induction coil with at least one electrical conductor, at least one substrate unit and at least one fastening unit with at least one fastening element, which fastens the induction coil to the substrate unit. 
     In one aspect of the invention, it is proposed for the substrate unit to have at least one through-flow opening, through which at least the fastening element is guided. In particular, a simple and cost-effective fastening of the induction coil can be achieved as a result. Advantageously, a fastening of the induction coil to the substrate unit can be produced by established methods which can be performed automatically. 
     An “induction oven device” is to be understood in particular as meaning at least a part, in particular a subassembly of an induction oven, wherein in particular accessory units for the induction oven may additionally be included, such as for example a sensor unit for external measurement of a temperature of an item of cookware and/or a food to be cooked. In particular, the induction oven device may also comprise the entire induction oven. An “induction oven” is to be understood in particular as meaning a household appliance which has at least one cooking compartment, at least one cooking muffle, at least one oven door and at least one heating unit, wherein the cooking compartment is outwardly delimited by the cooking muffle and the oven door and wherein the heating unit is provided to heat an item of cookware and/or food to be cooked situated in the cooking compartment to a predefined temperature during an operation of the induction oven, at least for preparation and/or storage, by way of an alternating field induced by the heating unit and to keep said item of cookware and/or food to be cooked at said predefined temperature. 
     Preferably, the induction oven has at least an inner housing and outer housing. An “inner housing” is to be understood in particular as meaning a wall unit which at least for the most part outwardly delimits at least one interior, in particular a cooking compartment, and itself is outwardly delimited at least by the outer housing. Advantageously, the inner housing features a ferromagnetic metal. Particularly advantageously, the induction coil is provided to inductively heat at least a part of the inner housing during an operation of the cooking appliance device. Preferably, the part of the inner housing comprises a top wall and/or a bottom wall of the inner housing, in particular in order to provide a conventional heating mode, also known as “top and bottom heating”. Preferably, the inner housing is embodied as a cooking muffle. A “cooking muffle” is to be understood as meaning an inner housing which, together with an oven door of the induction oven, at least for the most part outwardly delimits a cooking compartment of an induction oven. An “oven door” is to be understood in particular as meaning a wall which, in a closed state, fully covers an opening of the cooking compartment which faces an operator and, in an opened state, at least partially releases the opening. An “outer housing” of an appliance is to be understood in particular as meaning a wall unit which at least for the most part defines an outer area of the appliance. In this context, “at least for the most part” is to be understood in particular as meaning at least  60 %, advantageously at least 70%, particularly advantageously at least 80%, preferably at least 90% and particularly preferably fully. 
     A “heating unit” is to be understood in particular as meaning a unit which is provided to heat at least one food to be cooked and/or item of cookware arranged in a predefined heating region, and/or to keep said food to be cooked and/or item of cookware warm. In particular, the heating unit has at least one induction coil, through which current flows in particular during an operation of the heating unit and which generates at least one electromagnetic field for heating the food to be cooked and/or item of cookware and/or keeping said food to be cooked and/or item of cookware warm. The induction coil has at least one conductor, which for example can be produced by a punching and/or sawing and/or cutting, in particular beam cutting, of a metal plate. In particular, the conductor may be embodied as an individual wire and/or preferably as a Litz wire. In particular, a Litz structure of a conductor embodied as a Litz wire may compensate for the thermal expansion of the conductor. Advantageously, the conductor has at least one coating, which insulates the conductor thermally and/or electrically. 
     A “substrate unit” is to be understood in particular as meaning a unit which in particular can be connected to the inner housing in a fixed manner and which is provided to hold the induction coil in relation to the inner housing and/or the item of cookware and/or food to be cooked which is/are to be heated. In particular, the substrate unit is arranged between the induction coil and the inner housing. Alternatively, the induction coil could be arranged between the substrate unit and the inner housing. It would be conceivable for the cooking appliance device to have a plurality of substrate units, which in particular are arranged in a stacked manner and preferably hold a winding of the induction coil between individual layers in each case. It would be conceivable for the inner housing to serve an accommodation of at least the heating unit. For example, the substrate unit could be adhesively bonded and/or riveted and/or screwed to the inner housing. It would be conceivable for the substrate unit to be fastened directly to the inner housing, in particular to be embodied in one piece with the inner housing. This makes it possible to minimize a distance between the induction coil and the inner housing in particular. “Embodied in one piece” is to be understood in particular as meaning connected with a material fit, for example by a welding process, an adhesive bonding process, an injection molding process and/or another process appearing suitable to the person skilled in the art, and/or advantageously understood as meaning molded in one piece, such as by producing from a cast iron and/or by producing in a single or multi-component injection method and advantageously from a single blank. 
     In particular, the substrate could be fastened to the inner housing indirectly. Furthermore, the heating unit could have at least one thermal isolation, via which the substrate unit is fastened indirectly to the inner housing. Preferably, the substrate unit has at least one heat-resistant material. A “heat-resistant material” is to be understood in particular as meaning a material which withstands temperatures of at least 500° C., advantageously at least 550° C. and preferably at least 600° C., without changing from a chemical perspective. Particularly advantageously, the substrate unit has at least one electrically insulating material. An “electrically insulating material” is to be understood in particular as meaning a material which has a specific electrical resistance of at least 10 12  (Ω mm 2 )/m and in particular is non-conductive, at least in relation to a current flowing through the induction coil during operation. It would be conceivable for the substrate unit to at least partially consist of at least one heat-resistant plastic. 
     A “fastening unit” is to be understood in particular as meaning a unit which is provided to fasten the induction coil to the substrate unit at least partially, in particular fully. In particular, the fastening unit is embodied separately from the substrate unit and/or the conductor. Preferably, the fastening unit has at least one heat-resistant and/or electrically insulating material. Advantageously, it is possible to dispense with a use of additional thermal insulations for the fastening unit and/or the substrate unit. For example, the fastening unit could have a material which is identical to a material of the substrate unit. In particular, the fastening unit may have at least one fastening element for fastening the induction coil to the substrate unit. The fastening element may for example be a clamp, a screw, a flap, an adhesive and/or a plastic profile. 
     A “through-flow opening” is to be understood in particular as meaning a recess of the substrate unit which is at a distance from an edge of the substrate unit, and through which a first side of the substrate unit, which preferably runs along a main extension plane of the substrate unit, is connected to a second side of the substrate unit which lies opposite the first side. Preferably, the substrate unit has a large number of through-flow openings, which in particular are arranged periodically in parallel with the conductor. Particularly preferably, in an installed state the through-flow openings run along at least a majority of the conductor, in particular the entire conductor. Particularly preferably, the through-flow opening can be widened. In this context, an “opening which can be widened” is to be understood as meaning an opening, the circumference of which can be extended to at least twice, advantageously at least three times, particularly advantageously at least four times, preferably at least five times and particularly preferably at least six times the length. 
     The fastening element being “guided through the through-flow opening” is to be understood in particular as meaning that the fastening element has at least one contiguous subregion which in an installed state extends from the first side of the substrate unit to the second side of the substrate unit. 
     “Provided” is to be understood in particular as meaning especially designed and/or equipped. An object being provided for a particular function is to be understood in particular as meaning that the object fulfills and/or carries out this particular function in at least one application and/or operating state. 
     In a further aspect of the invention, which can be considered separately or in combination with the remaining aspects of the invention, it is proposed that the substrate unit features at least one silicate. A “silicate” is to be understood in particular as meaning a material which at least contains the chemical elements of silicon and oxygen. In particular, a silicate is to be understood as meaning a salt and/or an ester of an orthosilicic acid and in particular also the condensate thereof. In particular, this should be understood as meaning a mineral, the chemical composition thereof has at least one SiO 4  tetrahedron. Exemplary applications of silicate are fibers and/or glasses. Preferably, the substrate unit features at least basalt, spar, dolomite, diabase, anorthosite, coke, glass fibers, water glass and/or mica. Preferably, the substrate unit consists of the silicate at least partially, preferably for the most part and particularly advantageously fully. Particularly preferably, the substrate unit is embodied in a mat-like manner. A “mat-like element” is understood in particular as meaning an element for which a smallest possible notional cuboid exists, which just barely accommodates the element, whose shortest side corresponds to at most 30%, advantageously at most 20%, particularly advantageously at most 10%, preferably at most 5% and particularly preferably at most 2% of a longest side of the cuboid. In particular, a mat-shaped element can be stretched, preferably can be folded. In particular, the substrate unit may also be embodied in a plate-shaped manner. Preferably, the substrate unit has a thickness of at most 500 μm, advantageously at most 450 μm, particularly advantageously at most 400 μm, preferably at most 300 μm and particularly preferably at most 200 μm. This makes it possible to raise robustness and cost-effectiveness in particular. Advantageously, a thermal and/or electrical insulation of the induction coil may be provided. Particularly advantageously, it is possible to dispense with additional components for a thermal and/or electrical insulation of the induction coil. 
     It is further proposed for the fastening element to feature at least one silicate. In particular, a silicate of the fastening element may be different from a silicate of the fastening unit. Preferably, the silicate of the fastening element is identical to the silicate of the fastening unit. This makes it possible to raise robustness in particular. It is advantageously possible to avoid a recess in the thermal and/or electrical insulation of the induction coil generated by guiding the fastening element through the through-flow opening. 
     Furthermore, it is proposed for the substrate unit to be able to be pierced through, at least partially, in order to fasten the induction coil. The substrate unit being “able to be pierced through at least partially” is to be understood in particular as meaning that the substrate unit has at least one subregion which comprises at least a first subregion of the first side of the substrate unit and a second subregion of the second side of the substrate unit, which can be pierced through by a preferably elongated object in order to generate and/or widen the through-flow opening, advantageously without damaging further surrounding subregions of the substrate unit. It would be conceivable for the substrate unit to be able to be pierced through by the fastening element. Preferably, the substrate unit can be pierced through by a further element, for example a needle and/or a punching tool and/or a cutting tool. This makes it possible to achieve a simple and cost-effective production and/or adjustment of the induction oven device in particular. Advantageously, the through-flow opening can be generated and/or widened by established and cost-effective methods. 
     Advantageously, the substrate unit is at least partially fibrous. A “fibrous element” is to be understood in particular as meaning an element which at least partially consists of fibers. A “fiber” is to be understood in particular as meaning an elongated, mat-shaped element which is at least partially pliable. In this context, an “at least partially pliable element” is to be understood in particular as meaning that the element can experience curvatures of at least 20°, advantageously at least 30°, particularly advantageously at least 40°, preferably at least 50° and particularly preferably at least 60°, without experiencing a permanent deformation and/or damage. Preferably, the element is pliable enough in order to permit a combination of numerous such elements according to at least one predefined one-dimensional pattern, preferably to form a yarn and/or twine and/or a cord. Advantageously, the substrate unit is fully fibrous. It would be conceivable for the substrate unit to be at least partially wound around the induction coil. Preferably, the through-flow opening is embodied as a widened distance between individual fibers of the substrate unit. This makes it possible to raise robustness and to achieve a simple production of the substrate unit in particular. Advantageously, damage to the substrate unit due to a bending process can be avoided. Particularly advantageously, the substrate unit can be adjusted in a simple manner by adding further fibers. Furthermore, piercing through the substrate unit can be performed in a simple manner to generate and/or widen the through-flow opening. 
     Preferably, the substrate unit has at least one textile structure with a flat shape. Advantageously, the substrate unit is fully formed from the textile structure with a flat shape. A “textile structure with a flat shape” is to be understood in particular as meaning a structure which is formed from a large number of fibers, in particular fiber strands, which are combined according to at least one predefined, mat-shaped pattern. Exemplary textile structures with a flat shape include woven fabric and/or knitted fabric and/or crocheted fabric and/or braided fabric and/or stitched fabric and/or non-woven fabric and/or felt. This makes it possible to achieve an effective thermal and/or electrical insulation of the induction coil in a simple and cost-effective manner in particular. Advantageously, recesses in the thermal and/or electrical insulation of the induction coil can be avoided. Particularly advantageously, the substrate unit can be produced and/or adjusted in a simple and cost-effective manner. 
     Furthermore, it is proposed for the fastening element to be embodied as a thread and the induction coil to be fastened to the substrate unit by means of at least one seam which has the threads. In particular, the threads are able to penetrate the substrate unit according to various standardized stitching methods, which are listed in ASTM D-6193 and ISO 4915:1991 in particular. For example, the seam and/or the further seams could run according to a lockstitch method and/or a zig-zag method. In particular, a longitudinal direction of the thread may correspond to a longitudinal direction of a nearest conductor segment of the conductor. In particular, piercing through the substrate unit by way of at least one needle and/or at least one punching tool and/or at least one cutting tool forms the generating and/or widening of the through-flow opening. Advantageously, the thread may run over the conductor, at least in segments. Advantageously, the thread may run laterally next to the conductor, at least in segments. This makes it possible to achieve a simple and cost-effective production of the induction oven device in particular. Advantageously, established and cost-effective sewing machines can be used to produce the induction oven device. 
     In one advantageous embodiment, the substrate unit consists of basalt at least partially, preferably at least for the most part. Preferably, the substrate unit consists of basalt fibers at least partially, preferably fully. In particular, the basalt may contain at least one ferromagnetic material, in particular magnetite. In particular, the substrate unit may consist of pressed basalt fibers. Preferably, the substrate unit consists of basalt fibers which have been combined to form a textile structure with a flat shape. This makes it possible to raise robustness in particular. Advantageously, a compressive strength and impact resistance and heat resistance of the thermal and electrical insulation of the induction coil can be increased. 
     It is further proposed for the substrate unit to consist of glass fibers at least partially, preferably at least for the most part. It would be conceivable for the substrate unit to fully consist of glass fibers. Furthermore, it would be conceivable for the substrate unit to feature at least one glass-fiber-reinforced plastic. This makes it possible to increase flexibility in particular. Advantageously, a weight reduction and an elasticity of the thermal and electrical insulation of the induction coil can be increased. 
     Moreover, it is proposed for the fastening unit to have at least one cover element, which is arranged on a side of the induction coil which lies opposite the substrate unit and restricts a movement of the induction coil on this side. It would be conceivable for the fastening unit to have a large number of cover elements, which together cover the entire region. Preferably, the cover element is fastened to the substrate unit by means of the seam and/or further seam having the thread and/or further thread. Preferably, the fastening unit has precisely one cover element, which in particular covers the entire induction coil. In particular, a main extension plane of the cover element runs in parallel with a main extension plane of the induction coil. Advantageously, the cover element has at least one electrically insulating and/or heat-resistant material. Preferably, the cover element has a material which is identical to a material of the substrate unit. In particular, the cover element may be embodied in one piece with the substrate unit. It would be conceivable for the cover element and the substrate unit to be embodied as adjacent subregions of an element of the fastening unit and, advantageously, to be arranged around the induction coil by folding the element. This makes it possible to improve a retaining of the induction coil in particular. Advantageously, a movement of the induction coil along a direction perpendicular to a main extension plane of the substrate unit can be avoided. 
     Preferably, the cover element features at least one silicate. Particularly preferably, the cover element has a material which is identical to a material of the substrate unit. This makes it possible to achieve a simple production of the induction oven device and an improved thermal and electrical insulation of the induction coil in particular. Advantageously, the cover element can be produced by a method which is identical to a production of the substrate unit. Particularly advantageously, the induction coil may be thermally and electrically insulated on at least two sides. 
     The invention is further based on a method for producing an induction oven device with at least one heating unit, which has at least one induction coil with at least one electrical conductor and at least one substrate unit, wherein the induction coil is fastened to the substrate unit. 
     It is proposed for a fastening element to be guided through the substrate unit in order to fasten the conductor. This makes it possible to provide a method for producing an induction oven device with an increased robustness and a simplified production in particular. 
     In this context, the induction oven device should not be restricted to the application and embodiment described above. In particular, in order to fulfill a mode of operation described herein, the induction oven device may have a number of individual elements, components and units deviating from a number mentioned herein. 
     Further advantages result from the following description of the drawing. The drawings show eight different exemplary embodiments of the invention. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them to form useful further combinations. 
    
    
     
       In the drawings: 
         FIG. 1  shows a schematic front view of a cooking appliance with a cooking appliance device, 
         FIG. 2  shows an exploded representation of a part of the cooking appliance device, 
         FIG. 3  shows a schematic oblique view of a part of the cooking appliance device with a heating unit, 
         FIG. 4  shows a schematic top view of the heating unit with an induction coil and a substrate unit, 
         FIG. 5  shows a schematic flow diagram of a method for producing the cooking appliance device, 
         FIG. 6 a    shows a schematic top view of a part of a cooking appliance device with a first relative arrangement of a conductor in relation to a thread, 
         FIG. 6 b    shows a schematic top view of a part of a cooking appliance device with a second relative arrangement of a conductor in relation to a thread, 
         FIG. 6 c    shows a schematic top view of a part of a cooking appliance device with a third relative arrangement of a conductor in relation to a thread, 
         FIG. 7 a    shows a schematic top view of a part of a cooking appliance device with a further thread at a minimum distance from the side and a thread at a minimum distance from the opposite side, 
         FIG. 7 b    shows a schematic top view of a part of a cooking appliance device with a further thread at a minimum distance from the side and a thread running at a distance from the opposite side, 
         FIG. 7 c    shows a schematic top view of a part of a cooking appliance device with a further thread running at a distance from the side and a thread at a minimum distance from the opposite side, 
         FIG. 8 a    shows a schematic top view of a cutout of a cooking appliance device with a thread crossing a conductor, which is in contact with the conductor, 
         FIG. 8 b    shows a schematic top view of a cutout of a cooking appliance device with a thread crossing a conductor, which runs at a distance from the conductor in segments, and 
         FIG. 9  shows a schematic flow diagram of a further method for producing the cooking appliance device from  FIG. 8   b.    
     
    
    
     Only one of the objects present repeatedly in the figures is provided with a reference character in each case. 
       FIG. 1  shows a cooking appliance  30   a.  The cooking appliance  30   a  is embodied as an induction oven. The cooking appliance  30   a  has an outer housing  44   a.  The outer housing  44   a  defines an outer contour of the cooking appliance  30   a.  The outer housing  44   a  accommodates a user interface  48   a  of the cooking appliance  30   a.  The user interface  48   a  is provided to be operated by an operator in order to control the cooking appliance  30   a.  The cooking appliance  30   a  has an inner housing  42   a.  The inner housing  42   a  consists of a ferromagnetic metal. Alternatively, the inner housing  42   a  could have a non-magnetic material, in particular glass, preferably a glass ceramic. In this alternative embodiment, the inner housing  42   a  has a plurality of heating elements (not shown), which consist of a ferromagnetic metal. The cooking appliance  30   a  has an oven door  46   a.  The oven door  46   a  is situated in a closed state. The oven door  46   a  covers an opening  52   a  of a cooking compartment  28   a,  which fully faces an operator. The oven door  46   a  and the inner housing  42   a  together outwardly delimit the cooking compartment  28   a.  The cooking appliance  30   a  has a cooking appliance device  10   a . The cooking appliance device  10   a  is embodied as an induction oven device. 
     One part of the cooking appliance device  10   a  is shown in more detail in an exploded representation in  FIG. 2 . The cooking appliance device  10   a  has the inner housing  42   a.  The cooking appliance device  10   a  has two heating units  12   a.  The heating units  12   a  are embodied as identical to one another. The heating units  12   a  are arranged on a top wall  54   a  and on a bottom wall  56   a  of the inner housing  42   a.  Alternatively or additionally it would be conceivable for heating units  12   a  to be arranged on side walls or a rear wall of the inner housing  42   a.  Just one of the heating units  12   a  will now be described. 
     The heating unit  12   a  has an induction coil  14   a.  During operation of the heating unit  12   a,  an alternating current flows through the induction coil  14   a,  which generates an electromagnetic alternating field. The induction coil  14   a  is embodied in a plate-shaped manner. A main extension plane (not shown) of the induction coil  14   a  runs in parallel with a main extension plane of the top wall  54   a  and the bottom wall  56   a.  The induction coil  14   a  has conductor  16   a.  The conductor  16   a  is embodied as an individual wire. The conductor  16   a  is embodied as a blank individual wire. Alternatively, the conductor  16   a  could have an insulation. The conductor  16   a  features aluminum. Alternatively, the conductor  16   a  could feature copper. The conductor  16   a  is arranged as a right-angled spiral. The conductor  16   a  is wound around a coil center  34   a  of the induction coil  14   a.    
     The heating unit  12   a  has an induction coil  18   a.  The substrate unit  18   a  is embodied in a mat-like manner. The substrate unit  18   a  is arranged between the induction coil  14   a  and the inner housing  42   a.  The induction coil  14   a  rests fully against the substrate unit  18   a.  The substrate unit  18   a  serves to thermally and electrically insulate the induction coil  14   a.  The substrate unit  18   a  at least for the most part consists of a material which features at least the chemical elements Si and  0 . The material is a silicate. The substrate unit  18   a  is fibrous. The substrate unit  18   a  consists of mineral wool. The substrate unit  18   a  has basalt fibers. Alternatively or additionally, the substrate unit  18   a  could have spar fibers, dolomite fibers, diabase fibers, anorthosite fibers and/or coke fibers. The substrate unit  18   a  can be pierced through, at least partially, in order to fasten the induction coil  14   a.  The substrate unit  18   a  fully consists of a textile structure with a flat shape. The substrate unit  18   a  fully consists of a woven basalt fabric. Alternatively, the substrate unit  18   a  could partially consist of the woven basalt fabric. The substrate unit  18   a  has a large number of through-flow openings  24   a.  The through-flow openings  24   a  are arranged periodically. The through-flow openings  24   a  are arranged along a large number of straight lines. 
     The heating unit  12   a  has a fastening unit  20  (see  FIG. 3 ). The fastening unit  20   a  fastens the induction coil  14   a  to the substrate unit  18   a.  The fastening unit  20   a  fastens the conductor  16   a  to the substrate unit  18   a  such that it can move in a region in relation to the substrate unit  18   a.  In this context, the region extends over the entire extension of the induction coil  14   a.  The fastening unit  20   a  has a fastening element  22   a.  The fastening element  22   a  is embodied as a thread  22   a.  The induction coil  14   a  is fastened to the substrate unit  18   a  by means of a seam which has the thread  22   a.  The thread  22   a  is fully embodied from silicate. The thread  22   a  is fully embodied from water glass. Alternatively, the thread  22   a  could consist of mineral wool and/or glass fibers. The thread  22   a  is guided through a part of the through-flow openings  24   a . The thread  22   a  is guided through the through-flow openings  24   a  according to a lockstitch stitching method. In a perpendicular view of the substrate unit  18   a,  the thread  22   a  runs fully laterally next to the conductor  16   a.  The thread  22   a  runs in parallel with the conductor  16   a . The thread  22   a  runs at a distance from the conductor  16   a.    
     The fastening unit  20   a  has a further fastening element  32   a.  The induction coil  14   a  is fastened to the substrate unit  18   a  by means of a further seam which has a further thread  32   a . The further thread  32   a  is embodied as identical to the thread  22   a.  The further thread  32   a  has a further course which is identical to a course of the thread  22   a.  The further thread  32   a  is guided through a further part of the through-flow openings  24   a.  In a perpendicular view of the substrate unit  18   a,  the further thread  32   a  runs on a side of the conductor  16   a  which lies opposite the thread  22   a.  Before operation of the cooking appliance device  10   a,  a distance between the thread  22   a  and the conductor  16   a  is at least largely identical to a further distance between the further thread  32   a  and the conductor  16   a.    
     The fastening unit  20   a  has a cover element  26   a.  Alternatively, the fastening unit  20   a  could have a large number of cover elements  26   a.  The cover element  26   a  features a silicate. The cover element  26   a  has basalt fibers. Alternatively or additionally, the cover element  26   a  could have spar fibers, dolomite fibers, diabase fibers, anorthosite fibers and/or coke fibers. 
     The cover element  26   a  is embodied as identical to the substrate unit  18   a.  The cover element  26   a  is arranged on a side of the induction coil  14   a  which lies opposite the substrate unit  18   a . The cover element  26   a  and the substrate unit  18   a  are stitched together within the region. The cover element  26   a  and the substrate unit  18   a  are stitched to one another by means of the seam which has the thread  22   a.  The cover element  26   a  and the substrate unit  18   a  are stitched to one another by means of the further seam which has the further thread  32   a.  The cover element  26   a  and the substrate unit  18   a  touch in the region, at least in segments. The cover element  26   a  and the substrate unit  18   a  form an end stop with regard to a permitted movement of the conductor  16   a.  The end stop is formed by the seam and the further seam. 
     The induction coil  14   a  is fully in contact with the cover element  26   a.  Alternatively, the induction coil  14   a  could exclusively be in contact with the cover element  26   a  in the region. The cover element  26   a  restricts a movement of the induction coil  14   a  on this side. The cover element  26   a,  the thread  22   a  and the further thread  32   a  together define the region. The thread  22   a  and the further thread  32   a  form end stops, at which the substrate unit  18   a  and the cover element  26   a  are stitched. The end stops restrict a movement of the induction coil  14   a  in parallel with a main extension plane of the induction coil  14   a.  In the region, the substrate unit  18   a  and the cover element  26   a  restrict a movement of the induction coil  14   a  perpendicular to the main extension plane of the induction coil  14   a.  Permitted movements of the conductor  16   a  include a movement along a direction  40   a  facing away from a coil center  34   a,  which is facing away from the coil center  34   a  of the induction coil  14   a  in a perpendicular view of the substrate unit  18   a.  The length of the permitted movement along the direction  40   a  is identical to a length by which the conductor  16   a  stretches during operation of the cooking appliance device  10   a.  Permitted movements of the conductor  16   a  include a movement counter to the direction  40   a.    
     In  FIG. 4 , the cooking appliance device  10   a  is shown before operation of the cooking appliance device  10   a.  For reasons of clarity, the induction coil  14   a  is represented in a simplified form with a reduced number of windings and an hatched conductor  16   a.  In addition, the distance of the thread  22   a  and the further thread  32   a  from the conductor  16   a  is shown in a reduced manner. The region comprises the entire induction coil  14   a.  The fastening unit  20   a  has an additional thread  50   a.  The additional thread  50   a  runs along a smallest possible rectangle, which just barely accommodates a projection of the induction coil  14   a  onto the substrate unit  18   a.  The additional thread  50   a  fully encircles the induction coil  14   a.  The additional thread  50   a  serves to stabilize the substrate unit  18   a  and the cover element  26   a.  The conductor  16   a  experiences thermal expansions during operation of the cooking appliance device  10   a.  The thermal expansions generate stretching movements of the induction coil  14   a  in the direction  40   a.  The stretching movements are movements of the induction coil  14   a  which are permitted within the region. 
       FIG. 5  shows a schematic flow diagram of a method for producing the cooking appliance device  10   a.  In a winding step  100   a,  the induction coil  14   a  is produced by winding the conductor  16   a.  Alternatively, the induction coil  14   a  could be produced by winding a Litz wire and/or punching out the conductor  16   a  from a metal plate (not shown). 
     In an insulating step  110   a,  the induction coil  14   a  is laid onto the substrate unit  18   a  and covered by the cover element  26   a.  In this context, the insulating step  110   a  follows the winding step  100   a.    
     In a stitching step  120   a,  the substrate unit  18   a  and the cover element  26   a  are pierced through by a needle. The substrate unit  18   a  and the cover element  26   a  are stitched to one another according to the lockstitch stitching method. In this context, the thread  22   a  is guided through a part of the through-flow openings  24   a.  Subsequently, the further thread  32   a  is guided through a further part of the through-flow openings  24   a  in an identical manner. In this context, the stitching step  120   a  follows the insulating step  110 . 
     In an installation step  130   a,  the heating unit  12   a  is installed on the inner housing  42   a . The heating unit  12   a  is screwed onto the inner housing  42   a.  Alternatively, the heating unit  12   a  could also be clamped and/or riveted onto the inner housing  42   a.    
       FIGS. 6 a    to  9  show further exemplary embodiments of the invention. The following descriptions are essentially restricted to the differences between the exemplary embodiments, wherein with regard to components, features and functions which remain the same, reference can be made to the description of the exemplary embodiment in  FIGS. 1 to 5 . In order to differentiate the exemplary embodiments, the letter a in the reference characters of the exemplary embodiment in  FIGS. 1 to 5  is replaced by the letters b to i in the reference characters of the exemplary embodiments of  FIGS. 6 a    to  9 . With regard to parts that remain the same, in particular with regard to parts with the same reference characters, in principle, reference can also be made to the drawings and/or the description of the exemplary embodiment of  FIGS. 1 to 5 . 
     For the sake of clarity, conductors  16   b - g  which are covered by cover elements  26   b - g  in the following figures are represented with hatching. 
     In  FIGS. 6 a - c   , a part of cooking appliance devices  10   b,    10   c,    10   d  is shown in each case. Induction coils  14   b,    14   c,    14   d  of the cooking appliance devices  10   b,    10   c,    10   d  are fastened to substrate units  18   b,    18   c,    18   d  by means of seams which have threads  22   b,    22   c,    22   d.  Cover elements  26   b,    26   c,    26   d  are stitched to one another by means of the seams which have the threads  22   b,    22   c,    22   d.  In the cooking appliance device  10   b,  a thread  22   b  runs along a side of a conductor  16   b  which is oriented counter to a direction  40   b  facing away from a coil center (not shown), at a minimum distance from the conductor  16   b.  The conductor  16   b  is fastened to the substrate unit  18   b  such that it largely cannot move counter to the direction  40   b.  The substrate unit  18   b  fully consists of glass fibers. In the cooking appliance device  10   c,  a thread  22   c  runs along a side of a conductor  16   c  which is oriented along a direction  40   c  facing away from a coil center (not shown), at a distance from the conductor  16   c.  The conductor  16   c  is fastened to the substrate unit  18   c  such that it can move along and counter to the direction  40   c.  In the cooking appliance device  10   d,  a thread  22   d  runs along a side of a conductor  16   d  which is oriented along a direction  40   d  facing away from a coil center (not shown), at a minimum distance from the conductor  16   d.  The conductor  16   d  is fastened to the substrate unit  18   d  such that it cannot move along the direction  40   d.    
     In  FIGS. 7 a - c   , a part of cooking appliance devices  10   e,    10   f,    10   g  is shown in each case. In the cooking appliance devices  10   e,    10   f,    10   g,  threads  22   e,    22   f,    22   g  and further threads  32   e ,  32   f,    32   g  run along opposite sides of conductors  16   e,    16   f,    16   g.  In the cooking appliance device  10   e,  the thread  22   e  and the further thread  32   e  run at a minimum distance from the conductor  16   e.  The conductor  16   e  is fastened to a substrate unit  18   e  such that it cannot move along and counter to a direction  40   e  facing away from a coil center (not shown). In the cooking appliance device  10   f,  a thread  22   f  runs at a distance from a conductor  16   f.  A further thread  32   f  runs at a minimum distance from the conductor  16   f.  The conductor  16   f  is fastened to a substrate unit  18   f  such that it cannot move counter to a direction  40   f  facing away from a coil center (not shown). In the cooking appliance device  10   g,  a thread  22   g  runs at a minimum distance from a conductor  16   g.  The thread  32   g  runs at a distance from a conductor  16   g.  The conductor  16   g  is fastened to a substrate unit  18   g  such that it cannot move along a direction  40   g  facing away from a coil center (not shown). 
     In  FIGS. 8 a - b   , a part of cooking appliance devices  10   h,    10   i  is shown in each case. Induction coils  14   h,    14   i  of the cooking appliance devices  10   h,    10   i  are fully stitched to substrate units  18   h,    18   i  by threads  22   h,    22   i.  In the cooking appliance devices  10   h,    10   i  the thread  22   h,    22   i  runs over a conductor  16   h,    16   i,  at periodic distances in each case. The thread  22   h,    22   i  runs in a zig-zag pattern in each case. Through-flow openings  24   h,    24   i  form turning points of the zig-zag pattern in each case. The threads  22   h,    22   i  are guided through the through-flow openings  24   h,    24   i  according to a zig-zag stitching method in each case. Alternatively, the threads  22   h,    22   i  run in parallel with the conductors  16   h,    16   i,  in segments, in each case. In the cooking appliance device  10   h,  the conductor  16   h  is fastened to the substrate unit  18   h  such that it cannot move along a main extension plane of the induction coil  14   h.  The conductor  16   h  is embodied as a Litz wire. In the cooking appliance device  10   i,  a portion of the through-flow openings  24   i  run at a distance from the conductor  16   i.  Said portion of the through-flow openings  24   i  are arranged on a side of the conductor  16   i  which is oriented along a direction  40   i  facing away from a coil center (not shown). The conductor  16   i  is fastened to the substrate unit  18   i  such that it cannot move counter to the direction  40   i.  The cooking appliance devices  10   h,    10   i  have no cover elements. The seams which have the threads  22   h ,  22   i  stitch the induction coils  14   h,    14   i  to one of the substrate units  18   h,    18   i  in each case. 
       FIG. 9  shows a flow diagram of a method for producing the cooking appliance device  10   i.  In a positioning step  140   i,  the induction coil  14   i  is arranged on the substrate unit  18   i  in an unwound state. 
     In an embroidery step  150   i,  the induction coil  14   i  is simultaneously wound while the thread  22   i  is guided through the through-flow openings  24   i  according to the zig-zag stitching method. In this context, the embroidery step  150   i  follows the positioning step  140   i.    
     In an installation step  160   i,  the heating unit  12   i  is installed on the inner housing (not shown). The heating unit  12   i  is screwed onto the inner housing. Alternatively, the heating unit  12   i  could also be clamped and/or riveted to the inner housing. 
     REFERENCE CHARACTERS 
     
         
           10  Cooking appliance device 
           12  Heating unit 
           14  Induction coil 
           16  Conductor 
           18  Substrate unit 
           20  Fastening unit 
           22  Thread 
           24  Through-flow opening 
           26  Cover element 
           28  Cooking compartment 
           30  Cooking appliance 
           32  Thread 
           34  Coil center 
           40  Direction 
           42  Inner housing 
           44  Outer housing 
           46  Oven door 
           48  User interface 
           50  Thread 
           52  Opening 
           54  Top wall 
           56  Bottom wall 
           100  Winding step 
           110  Insulating step 
           120  Stitching step 
           130  Installation step 
           140  Positioning step 
           150  Embroidery step 
           160  Installation step