The present invention relates to an induction heating device comprising a central element and at least one ferrite bar. With the term “ferrite bars” we mean any kind of elongated magnetic field concentrator.
The above heating devices are used to heat and cook food thanks to heat energy generated in a ferromagnetic container placed above the coil assembly and supported on a ceramic glass or the like.
The known induction heating devices consist of a series of layers dedicated to different functions. All of them are composed of different materials and geometries. In some solutions layers are connected with glue. All the parts (with the exception of the support plate, usually made of aluminum) have a hole in the center which is designed to allow the insertion of a sensor holder for a thermal sensor contacting the ceramic glass. On the top of the last layer, i.e. the coil assembly, there is a thermal insulating layer for instance of rock wool. The sequence of the layers, starting from the top is: rock wool>glue>copper coil>glue>mica>glue>ferrite>glue>aluminum base. Mica and copper coil are usually supplied as a single assembly.
Other heating induction devices, for instance as described in EP0713350 and EP1560462, comprise a disk-shaped plastic support interposed between the support plate and the coil assembly and having a plurality of housings for containing the ferrite bars. Also in these solutions glue is used for holding together the different layers.
All the above known solutions present drawbacks, either in view of the extensive use of glue which makes the assembly process quite complex and unreliable in terms of controlled final dimensions, or in view of the increase of cost due to the use of quite complex and large components as the disk-shaped plastic supports. Another problem is linked to the need of having, in an automated assembly process, a reliable and constant thickness of the flat induction heating device, particularly because the quantity of glue cannot always being dosed in a constant manner.
In one aspect, the disclosure relate to an induction heating device, including a planar central element having a plurality of radial seats, at least one ferrite bar, wherein each of the radial seats is dimensioned to receive an end of the at least one ferrite bar with a predetermined degree of interference so that the at least one ferrite bar extends radially from and centered on the planar central element, a base disposed below the planar central element, and a coil assembly disposed above the planar central element, opposite the base. The at least one ferrite bar is radially retained by the respective radial seat of the planar central element, and wherein the at least one ferrite bar is vertically retained between the coil assembly and the base.
In another aspect, the disclosure relates to an induction cooktop, including a plurality of ferrite bars, a central element having a plurality of radial seats dimensioned to receive and locate ends of the plurality of ferrite bars with a predetermined degree of interference so that the plurality of ferrite bars extend radially from and centered on the central element between the coil assembly and the support plate, the predetermined degree of interference radially retaining the plurality of ferrite bars, a glass support plate positioned below the central element and engaged with the central element, a coil assembly positioned above the central element and engaged with the central element, wherein the plurality of ferrite bars are vertically sandwiched between the coil assembly and the glass support plate.
Further advantages and features according to the present invention will be clear from the following detailed description, provided as a not limiting example, with reference to the attached drawings, in which:
With reference to the drawings, the induction heating device comprises a central component K composed of a co-injection of two different materials. With reference to
The shape of the component K recalls that of a snowflake, since it comprises a central portion 10 shaped as a regular polygon, for instance an hexagon (where the rubber or similar elastomeric material is centrally co-injected), on whose apexes 10a are integrally formed other regular auxiliary polygons 12, in the shown example triangles.
Such shape is due to the main technical purpose of the component K, i.e. to constrain the ends of ferrite bars 4 in the position required to channel or concentrate the electromagnetic field. Between each side 10b of the hexagon defining the central portion 10 of the component K and two facing sides 12a of two adjacent auxiliary triangles 12 it is defined a quadrangular seat 14 (open on top and bottom) for an end 4a of a ferrite bar 4. In the example shown in
The sensor holder 1 is a co-injection of rubber, with a total height slightly higher than the thickness of the central portion 10, because the holder 1 needs to generate a spring effect to keep a sensor 8 (
The central portion 10 of the component K is also provided with a plurality of elastic hooks 16 and 18 which are oriented parallel to the central symmetry axis of the component K. A first crown of upper hooks 16 can be seen in
A thermal insulation layer 7, for instance of rock wool, is then placed on the copper coil 6 and a temperature sensor 8, for instance a NTC sensor, is joined to the central component K through its insertion in corresponding joints 26 (
The embodiment shown in
In the embodiment shown in
The solution according to the invention, independently on which embodiment is used, has many benefits in terms of cost reduction and improved assembly procedure.
First of all, it is possible to get rid of the glue required, in the known solution, to position the ferrite bars on the aluminum base. Accordingly, there is also a decrease of the assembly time of the induction heating device and of the ferrite bars, by replacing the glue with snap-engaging fastener as hooks integral with a central simple component. There is a more accurate positioning of the ferrite bars, with a reduction in position variability caused by the unreliable quantity (and thickness) of the glue, and therefore a better control of the electromagnetic field in the working conditions of the induction heating device. It is also possible to avoid the use of glue required to position the mica layer on the ferrite, with a decrease of connection time of the mica layer by replacing the glue with snap-engaging fasteners.
Last but not least it is possible to easily integrate the temperature sensor holder with a decrease of the number of components, increasing the stability of the sensor holder because it is no longer connected with fasteners, but it is part of a single body.
This application is a continuation of U.S. application Ser. No. 15/148,621, filed May 6, 2016, now issued as U.S. Pat. No. 10,531,522, issued on Jan. 7, 2020, which is a continuation of U.S. application Ser. No. 13/775,945, filed Feb. 25, 2013, now issued as U.S. Pat. No. 9,370,051, issued on Jun. 14, 2016, both of which are incorporated herein by reference in their entirety.
Number | Name | Date | Kind |
---|---|---|---|
3953783 | Peters, Jr. | Apr 1976 | A |
3980858 | Hibino | Sep 1976 | A |
4629843 | Kato | Dec 1986 | A |
4792652 | Seguy | Dec 1988 | A |
5227597 | Dickens | Jul 1993 | A |
5665263 | Gaspard | Sep 1997 | A |
6594885 | Abdel-Tawab et al. | Jul 2003 | B2 |
9370051 | Fossati | Jun 2016 | B2 |
20030164370 | Aihara et al. | Sep 2003 | A1 |
20070278215 | Schilling | Dec 2007 | A1 |
20090020526 | Roux | Jan 2009 | A1 |
20100206871 | Kataoka | Aug 2010 | A1 |
20100282737 | Acero Acero et al. | Nov 2010 | A1 |
20110100980 | Kitaizumi | May 2011 | A1 |
20110163087 | Wakashima et al. | Jul 2011 | A1 |
20120111854 | Gaspard | May 2012 | A1 |
20120223070 | Matsui | Sep 2012 | A1 |
Number | Date | Country |
---|---|---|
3731762 | Mar 1989 | DE |
19955457 | May 2001 | DE |
102010030392 | May 2011 | DE |
0713350 | May 1996 | EP |
1335632 | Aug 2003 | EP |
1560462 | Aug 2005 | EP |
0743805 | Nov 1996 | ES |
4135270 | Aug 2008 | JP |
20080030737 | Apr 2008 | KR |
WO-02051571 | Jul 2002 | WO |
2011138715 | Nov 2011 | WO |
WO-2011138715 | Nov 2011 | WO |
Entry |
---|
European Patent Application No. 12156872.9, Filed Feb. 24, 2012, Applicant: Whirlpool Corporation. European Search Report dated Jul. 5, 2012. |
Number | Date | Country | |
---|---|---|---|
20200120763 A1 | Apr 2020 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 15148621 | May 2016 | US |
Child | 16715304 | US | |
Parent | 13775945 | Feb 2013 | US |
Child | 15148621 | US |