Abstract:
A carrier for a flat induction coil of an induction heating device has an upper supporting plate and a lower supporting plate. The plates are mechanically interconnected and form a narrow gap for the introduction of the induction coil formed by a single, continuous coil wire in several windings. As a result of the mutual spacing of the two supporting plates, the coil wire can be secured and is therefore fixed in position.

Description:
[0001]     The following disclosure is based on German Patent Application No. 102005005526.5 filed on Jan. 31, 2005, which is herewith incorporated into this application by explicit reference.  
       FIELD OF APPLICATION AND PRIOR ART  
       [0002]     The invention relates to a carrier for an induction coil, particularly having a flat or shallow construction, as well as an induction heating device and a method for the manufacture of such an induction heating device and an induction hob.  
         [0003]     It is known for example from U.S. Pat. No. 5,686,006 in the case of an induction heating device of an induction hob to wind in single layer form the coil wire onto a carrier with prefabricated grooves or groove-like depressions and it is for example fixed by bonding.  
       PROBLEM AND SOLUTION  
       [0004]     The problem of the invention is to provide an aforementioned carrier, an induction heating device and a method for the manufacture of an induction heating device obviating the prior art difficulties and in particular enabling the simple manufacture of an induction coil with a precisely defined shape and construction.  
         [0005]     The set problem is solved by a carrier for an induction coil with a substantially flat and extension along plane or an area, said carrier having upper means and lower supporting means, both supporting means being mechanically interconnected and forming a narrow gap for the introduction of the induction coil. The problem is also solved by an induction heating device with an induction coil and with an aforementioned carrier, together with an induction hob having the aforementioned induction heating device. The problem is additionally solved by a method for the manufacture of an induction coil with a carrier, which has a substantially flat and extension in an area and upper means and lower supporting means, said two supporting means being mechanically interconnected. They form a narrow gap for the introduction of the induction coil and, starting on the radial inside on the carrier an induction coil wire is wound into the gap between the supporting means, winding taking place radially from the inside to the outside. Advantageous and preferred developments of the invention form the subject matter of further claims and are explained in greater detail hereinafter. By express reference the wording of the claims is made into part of the content of the description. Features describing both the carrier and the induction heating device and manufacturing method are in part only referred to once hereinafter. However, independently of one another, they apply to the carrier, induction heating device and the manufacturing method for the same.  
         [0006]     The carrier has upper supporting means and lower supporting means forming a narrow gap. They can for example be constructed in a substantially plate-like or in the form of a plane. Into said narrow gap, which can also be in the form of a very deep groove, the induction coil is introduced or inserted. The induction coil is advantageously formed from a continuous coil wire, which with particular advantage is a relatively thick multiple strand. An insulation of the coil wire to the outside or the individual strands advantageously takes place by a varnish-like coating, in place of a coating-like plastic jacket. With particular advantage the coil wire is wound into the gap in such a way that the resulting induction coil is in single layer form.  
         [0007]     It is advantageously possible with a single layer induction coil, particularly if the mutual spacing of the two supporting means or the gap is much the same as the coil wire thickness and the coil wire is placed in the gap under a slight clamping action. This makes it possible to fix the coil wire or the individual windings in position for a stable, permanent construction of the induction coil or an induction heating device. There is no need for further bonds or fixtures.  
         [0008]     It is possible to manufacture the carrier as a subassembly or substantially or completely from a single part. The supporting means can be connected to a connecting piece, which is particularly shaped in the central area. Complicated assembly steps before and after winding on or introduction of the coil wire are consequently unnecessary. It can be made from plastic. Alternatively, at least the lower supporting means can comprise ferromagnetic material, for example can be in strip form with a radial direction or can comprise the same and this in particular also applies to the upper supporting means. Thus, the magnetic field can be diverted and in this way the overall inductance of the induction coil is modified.  
         [0009]     The supporting means form advantageous supporting surfaces bounding the gap and therefore the space into which is introduced the induction coil or coil wire. For the construction of the supporting means or the supporting surfaces formed by them a number of different possibilities exist. It is firstly possible to construct them in full-surface manner or as closed supporting surfaces. This makes it possible to create a very stable carrier for example. It is also possible for at least one of the supporting means or supporting surfaces to have recesses and/or openings. They can perform numerous functions, as will be described hereinafter. For example, openings can serve as ventilation apertures for cooling the induction coil. Material and weight can also be saved. A construction of supporting means with openings can for example be built up in the manner of a spoked wheel, the coil wire engaging on the spokes. Further possibilities exist for an advantageous manufacturing method and these will be described in greater detail hereinafter.  
         [0010]     At least one or both of the supporting surfaces can be constructed in substantially planar manner or without elevations. Alternatively a row of elevations can be located on at least one of the supporting surfaces. They can define the path of the coil wire in the form of spacers or introduction grooves or prefabricated paths. This is particularly advantageous if the mutual positioning of the windings is to be precisely defined and in particular if the windings should not engage with one another and instead have a certain mutual spacing. These elevations can have an elongated structure and follow the coil windings or gaps. However, for saving material, they can also comprise a row of adjacent elevations defining the spiral path.  
         [0011]     The elevations can project over a supporting surface of a supporting means to such an extent that they form a certain stop for the coil wire. However, on introducing or winding on the coil wire it must still be possible to press it with a certain force through a narrowed cross-section into the inner area of the coil or the gap between the supporting means. In particular a multistrand coil wire here offers an advantageous deformability. A cross-sectional reduction in the gap through the elevations can be between approximately 10 and 20%. This is also considered adequate to bring about a sufficient positional fixing.  
         [0012]     The path of the induction coil or coil wire predeterminable by such elevations can be such that in the central area there is either no spacing or a very limited spacing between adjacent windings. The spacing can increase towards the outside, because this can define a type of power density of the induction heating device.  
         [0013]     The interconnection of the two supporting means in a central piece or central area can be integral, as stated hereinbefore. It is additionally possible following the winding on of the induction coil to provide in the outer area further connections or fixtures, because then the gap need no longer be accessible. A connecting piece in the centre can have an opening or a hole in order to render said area accessible. For example, a temperature sensor can be introduced into the same and measures the temperature above the induction coil. Particularly when using an induction heating device in an induction hob this is of interest in order to determine the temperature of a glass ceramic hotplate above the same or indirectly the temperature of a cooking vessel placed thereon. The connecting piece can have fastening possibilities for a temperature sensor, for example locking projections or recesses.  
         [0014]     Onto an outside or top side of the carrier can be shaped spacers or the like. With the aid thereof it can in particular be applied to the underside of a glass ceramic plate with a precisely defined spacing, particularly as an induction heating device in an induction hob.  
         [0015]     According to a further development of the invention the aforementioned openings or apertures can be so constructed in at least one of the supporting means and can be used for introducing spacers from the outside into the gap. This is particularly advantageous if juxtaposed windings of the induction coil have a certain mutual spacing. Thus, following the winding in of a winding a spacer can be introduced on its radial outside. As it is introduced from the outside through one of the supporting means, it does not hinder the introduction of the coil wire. The introduced spacer advantageously engages on the inner winding or defines the radial spacing of the outer winding. The said spacers can in particular be rod-like or projection-like. With particular advantage they engage in both supporting means and are consequently fixed in position. When the induction coil is wound up, they can remain in the carrier for a permanent induction coil design.  
         [0016]     Apart from the actual induction coil, ferrites can be provided on the carrier, for example on an underside. In particular they are relatively flat and have a spoke-like or radial configuration. They can be introduced, fixed or bonded into corresponding receptacles on the underside of the carrier.  
         [0017]     During the manufacture of the induction coil winding starts from the radial inside. Since, starting from the radial inside, a connection possibility must be created, on one of the supporting means can be provided an opening or a passage through which the start of the coil wire for the induction coil can be led to the outside. For the simplified passage of the coil wire, said passage can be enlarged. It is advantageously elongated or in the form of a wide slit, which extends radially into an outer area and in particular to shortly before the outer edge or even through the latter. As a result the passage of the coil wire is relatively simple. In addition, such a radially directed slit does not impede the supporting of the individual circumferentially directed coil windings, which are therefore essentially at right angles thereto. As stated hereinbefore, such a slit can also assume functions such as cooling air supply or the like.  
         [0018]     Following the introduction of one end of the induction coil or coil wire, the actual winding up process can commence. Numerous possibilities exist for this and in particular the carrier rotates with the coil wire supply fixed. Through the precise definition of the gap height between the supporting means or through the aforementioned elevations, it is possible for the coil wire to be adequately precisely fixed in position by a clamping action. Thus, the induction coil can be manufactured without bonding or other fastenings.  
         [0019]     These and further features can be gathered from the claims, description and drawings and the individual features, both singly or in the form of subcombinations can be implemented in an embodiment of the invention and in other fields and can represent advantageous, independently protectable constructions for which protection is claimed here. The subdivision of the application into individual sections and the subheadings in no way restrict the general validity of the statements made thereunder. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     Embodiments of the invention are diagrammatically illustrated in the attached drawings, wherein show:  
         [0021]      FIG. 1 A  lateral section through a carrier with different construction possibilities or details.  
         [0022]      FIG. 2 A  carrier corresponding to  FIG. 1  with a wound up induction coil.  
         [0023]      FIG. 3 A  section through an induction hob with induction heating device and an induction coil corresponding to  FIG. 2  placed below a glass ceramic hotplate. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0024]      FIG. 1  shows in exemplified manner an induction coil  11  and various construction possibilities are illustrated. The induction coil  11  has a carrier  12 . It comprises an upper plate  14  as the upper supporting means and a lower plate  15  as the lower supporting means. The two plates  14 ,  15  are connected by a centrepiece  16  and in particular the entire carrier  12  is integrally constructed, for example from plastic.  
         [0025]     In the centrepiece  16  is provided a central recess  18  as an elongated hole, which can fulfil various functions, inter alia for the passage of a temperature sensor for engaging on a hotplate located above the same. It is also used for the passage of a cooling air flow. The central recess  18  also saves material.  
         [0026]     It is also possible to provide in the surface of one of the two plates  14 ,  15  or in both plates ventilation openings  20  with intermediate webs  21 . They can for example be constructed as radially directed slots. Apart from the improved ventilation function, they can also save material. It is also possible to bring about a supply here to the coil wire winding between the plates  14 ,  15 . As the webs  21  of plates  14 ,  15  are also located between the ventilation openings  20 , an adequate supporting or positional securing of the windings  30  is ensured. It is for example also possible to arrange the ventilation openings  20  in the upper plate  14  so as to be offset with respect to those of the lower plate  15 . The webs  21  and the outer circumferential rim in such a case create an adequate supporting surface for the windings  30 .  
         [0027]     To the right on carrier  12  is shown in exemplified manner how a ventilation opening can pass through the right-hand side in the form of slot  22  or is open to the edge. Into such a slot can be laterally introduced in particularly advantageous manner an inner connection end for the induction coil or the windings  30 .  
         [0028]     In the left-hand area of the carrier  12  is also shown how it is possible to provide a hole  24  for a spacer  26 . Said hole  24  passes as hole  24   a  through the upper plate  14  and extends in part as lower hole  24   b  into the lower plate  15 . A spacer  26  is introduced into said hole  24 , advantageously by clamping. From the outlet, this takes place following the introduction of the inner winding  30  to the right alongside spacer  26 . From the outside the next outer winding  30  is then wound onto the left-hand side of the spacer  26 , so that then between the two windings is maintained a spacing with the spacer thickness. As a result of different placing of the holes  24  or thickness of the spacer  26 , it is possible to vary the spacings between juxtaposed windings.  
         [0029]     An alternative method to the spacer  26  is shown in the right-hand area, where the windings  30  are directly juxtaposed or contact one another in a central area of the induction coil. As from roughly half the radius elevations  28  are provided and in the embodiment shown they are formed on the supporting surface constituted by the lower plate  15 . The elevations  28  become wider with increasing radius of the windings. Thus, the spacing of juxtaposed windings  30  increases, which can inter alia take place for reducing the power density in the radially outer area.  
         [0030]     In one development the elevations  28  can be in the form of longitudinal elevations, which have a spiral configuration corresponding to the path of the individual windings  30 . They can either be continuous, or can be constructed with mutual spacings as individual elevations along an imaginary line and as a result form a type of line or linear stop for each individual winding.  
         [0031]     The height of the elevations  28  is advantageously such that on introducing the coil wire  31  or windings  30  they are introduced from the radial outside. They are introduced with sufficient force that they just overcome sufficient elevations  28  to enable them to follow the correct track. The elevations  28  can be given a flat, central protuberance. Preferably and as shown they are constructed with a triangular cross-section, constant height and varying width. Thus, the windings  30  are centred at the lowest point between two elevations  28  and in the desired position.  
         [0032]      FIG. 2  shows an induction coil  11  in partial section with introduced windings  30  of coil wire  31 . However, compared with  FIG. 1  there is here a constant mutual spacing of the windings  30  or the latter are in precise engagement with one another. Thus, there are no spacers  26  or similarly functioning elevations  28 . It is also clear that the thickness of the coil wire  31  roughly corresponds to the height of the groove  17  between plates  14  and  15 , so that there is a very good fixing of the position.  
         [0033]      FIG. 2  also shows connections on the induction coil  11 , namely an outer connection  32   a  and an inner connection  32   b . In particular, the inner connection  32   b  can be passed out through a corresponding opening, for example a ventilation opening  20  or a slot  22  according to  FIG. 1  on the lower plate  15 .  
         [0034]      FIG. 3  shows in section an induction hob  35 , an induction coil  11  being positioned below a glass ceramic hotplate  36 . Its carrier  12  or the upper carrier plate  14  has spacers  38  constructed as elevations. Thus, the induction coil  11  with the top of plate  14  engages on the underside of the glass ceramic plate  36 .  
         [0035]     In much the same way as in  FIGS. 1 and 2 , in groove  17  the carrier  12  has several windings  30  of a coil wire  31 . Corresponding connections  32   a ,  32   b  are led out and in particular guided into a supply  40  in which the induction coil  11  is supplied with power via connections  32 . No further details regarding the supply  40  are necessary, because such a connection can be readily implemented by an expert.  
         [0036]     A central recess  18  passes through a centrepiece  16  in the centre of carrier  12  and in the same is located a temperature sensor  42 . Its upper part engages on the underside of the glass ceramic plate  36  and can determine the temperature thereof. This more particularly serves to prevent overheating of the glass ceramic plate and to give the temperature thereof to a hot indicator or the like of the hob  35 .  
         [0037]     In much the same way as the inner connection  32   b  can be fixed through a corresponding slot or opening in the lower plate  15 , the outer connection  32   a  can pass through a similar opening. However, there is no fixing by radially outwardly connecting windings  30 , so that there must be a clamping action in the slot in lower plate  15 . Alternatively fixing can take place by bonding or by leading the connection  32   a  to a supply  40  according to  FIG. 3 a  securing in position can take place.