Patent Grant
8912473
1.Field of the Invention
The present invention concerns a variable-size induction heating plate, and an induction cooking surface integrating such a plate.
2. Description of the Related Art
The present invention applies generally to the field of domestic induction cooking appliances, such as induction vitroceramic cooking surfaces.
An induction heating plate generally consists of a circular winding adapted to the dimension of a cooking vessel of given size.
It can equally consist of a plurality of concentric windings enabling adaptation to different diameters of vessels disposed on the cooking surface above the plate.
A heating plate can equally consist of a plurality of windings disposed side by side and supplied with power by independent generators, as described in patent application FR 2 758 994.
Also known are cooking surfaces comprising a plurality of small windings disposed in a cooking surface. One such cooking surface is described in the document FR 2 863 039 in particular. That document describes a set of circular windings disposed side by side so as to cover all of the area of the cooking surface. In this kind of set, the windings are magnetically independent and are controlled independently so that each heating plate is determined individually as a function of the position of the vessel on the cooking surface, facing the windings.
However, as a function of the position of the vessel on the cooking surface, it is not rare for a significant proportion of a group of windings not to be covered by the vessel, with the result that the power delivered by the induction winding is low.
The power delivered, by a particular heating plate depends on the electromagnetic matching between the induction winding and the vessel disposed above it. The vessel is seen as a resistive load by the current generator feeding the induction winding. In principle, induction heating devices are designed to optimize the electromagnetic matching and to maximize the power delivered when the vessel completely covers the area of the induction winding.
An object of the present invention is to resolve the drawbacks cited above and to propose a variable-size induction heating plate guaranteeing delivery of high power to a vessel regardless of its size.
To this effect the present invention concerns a variable-size induction heating plate comprising at least two sets of a plurality of windings disposed side by side in a plane, each set of a plurality of windings being adapted to constitute a heating plate.
According to the invention, the heating plate comprises control means adapted on the one hand to control said sets for independent operation and on the other hand to control said sets for synchronous operation, each set being supplied with power by a single current generator.
Thus the induction heating plate has the advantage of being able to function as two medium-size independent heating plates or as a single, larger plate.
By using a plurality of windings in each set constituting a heating plate, the overlapping proportion of the induction windings is very high when a vessel is placed on both sets.
According to one advantageous feature of the invention, the sets include exactly the same number of windings.
The windings of each set are preferably tangential to a circle corresponding to the dimension of the heating plate associated with that set, well adapted to the circular shape of a standard cooking vessel.
Further, each set includes at least three equidistant windings, enabling good distribution in the plane of the heating plate of the area covered by the induction windings facing the bottom of a vessel.
Thanks to this equidistant disposition of the windings, the bottom of a vessel placed on three equidistant windings achieves an overlap of greater than 70%.
One embodiment of the heating plate includes two sets, each set including at least three equidistant windings, at least two windings of a first set being disposed face to face with at least two respective windings of a second set.
This arrangement produces a heating plate wider at its center, well suited to heating larger vessels when the sets of windings function in synchronized mode.
Moreover, the area of the induction windings covered by a vessel placed, at the center of the two sets is greater than 50% with a vessel of a size such that it completely covers a set of induction windings. Moreover, the area of the bottom of a vessel facing the windings of a set represents at least 70% of the total area of the bottom of the vessel.
The windings of each set are preferably tangential to an ellipse corresponding to the dimension of a single large heating plate.
The present invention also concerns an induction cooking surface comprising a heating plate according to the invention.
That cooking surface has features and advantages analogous to those described previously in relation to the heating plate.
Other features and advantages of the invention will become more apparent in the course of the following description.
In the appended drawings, which are provided by way of nonlimiting example.
One embodiment of an induction heading plate of the invention is described next with reference to
In this embodiment, the heating plate comprises two sets 10, 10′ of a plurality of windings 10a, 10b, 10c, 10′a, 10′b and 10′c, all disposed in a plane parallel to the cooking surface.
As shown clearly in
Thus each set 10, 10′ of three windings is inscribed in a circle, as shown in
In this embodiment, the windings are disc-shaped and tangential to the circle defining the heating plate.
Each winding consists of an electrically conductive coil.
In practice, each winding can consist of a flat, spiral coil of multistrand copper wires.
The electrically conductive coils of each winding are not parallel to the electrically conducting coils of the adjacent windings. There is therefore virtually no inherent magnetic coupling between two adjacent windings.
Moreover, the two sets of windings are disposed side by side in a plane parallel to the cooking surface and are substantially inscribed in an oval or elliptical shape.
In practice, each set 10, 10′ includes two equidistant windings 10a, 10b and 10′a, 10′b facing each other.
As shown in
The windings of each set 10, 10′ are preferably electrically connected in series to each generator 11, 11′. Thus, in contrast to a parallel circuit, it is possible to prevent overheating of a winding not covered by a small vessel placed on the set.
Control means 12, 12′ provide for operation in two configurations.
If the heating plates consisting of each set 10, 10′ are used independently, as shown in
On the other hand, if the heating plate is used as a single plate for heating a larger vessel, as shown in
In practice, and by way of nonlimiting example, the diameter of each induction winding 10a, 10b, 10c, 10′a, 10′b, 10′c is approximately 100 mm. Each set 10, 10′ of three windings disposed in a triangle is then inscribed in a circle of approximately 200 mm, which corresponds to a plate of average size.
The juxtaposition of two sets 10, 10′ in two triangular arrangements facing in opposite directions produces a cooking area approximately 200 mm wide and 400 mm long.
The variable-size heating plate therefore offers the possibility of using two independent heating plates each consisting of three windings of each set 10, 10′ , a central circular plate of medium size consisting of four windings 10a, 10b, 10′a, 10′b controlled synchronously, or a large elliptical plate consisting of the six windings 10a, 10b, 10c, 10′a, 10′b, 10′c controlled synchronously.
Thus a variable-size heating plate of this kind accepts, on the one hand, one or two small vessels, of the order of 12 to 20 cm diameter, disposed side by side, and, on the other hand, a vessel of medium size, of the order of 25 cm diameter, or a large oval vessel, up to 40 cm long.
As shown clearly in
It will be noted that if each set 10, 10′ were replaced by a single circular induction winding with a diameter substantially equal to 200 mm, the same vessel would cover only approximately 40% of the area of the induction windings.
Thus the induction heating plate of the invention optimizes the area of the induction windings covered by a vessel whatever its size, and thus guarantees a high power in operation for the various uses of the heating plate.
Moreover, it is important that the total area covered by the induction windings disposed under the bottom of the vessel be as large as possible to guarantee a good distribution of temperature in the vessel.
Using small individual windings, it is possible to improve the distribution of the area of the windings facing the bottom of the vessel, and thus to guarantee a good distribution of heat in the vessel.
Thus, thanks to the triangular arrangement of three windings under the bottom of a vessel whose diameter substantially corresponds to the dimension of the circle tangential to the three windings, more than 70% of the bottom of the vessel overlaps the induction windings.
The shape and the number of windings of each set of the variable-size heating plate are not limited, of course.
Other examples of heating plates of the invention are shown by way of nonlimiting example in
Thus, in
As shown in
Plates of variable size and variable shape, for example round, oval or other shape, can be obtained in this way.
There is obtained in this way a heating plate of variable size for use in an induction cooking surface having great flexibility of use as a function of the size of the cooking vessels.
The present invention is not limited to the embodiments described above, of course.
Thus the heating plate could include sets of windings different from each other.
Moreover, the heating plate could include a greater number of sets of windings, for example three sets.
Finally, the shape of the windings is not limited to a disc shape, and can be different, for example oval or another shape.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05 13362 | Dec 2005 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR2006/002853 | 12/22/2006 | WO | 00 | 6/26/2008 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2007/074233 | 7/5/2007 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4074101 | Kiuchi et al. | Feb 1978 | A |
| 4987828 | Nuns et al. | Jan 1991 | A |
| 5136277 | Civanelli et al. | Aug 1992 | A |
| 5658478 | Roeschel et al. | Aug 1997 | A |
| 5808280 | Gaspard | Sep 1998 | A |
| 5893996 | Gross et al. | Apr 1999 | A |
| 5900174 | Scott | May 1999 | A |
| 6184501 | Zapf | Feb 2001 | B1 |
| 6232731 | Chapman | May 2001 | B1 |
| 6259069 | Schotten et al. | Jul 2001 | B1 |
| 6263782 | Brindani et al. | Jul 2001 | B1 |
| 6528770 | Akel et al. | Mar 2003 | B1 |
| 6614006 | Pastore et al. | Sep 2003 | B2 |
| 6633023 | Cornec et al. | Oct 2003 | B2 |
| 7202451 | Uchida et al. | Apr 2007 | B2 |
| 7361870 | Cornec et al. | Apr 2008 | B2 |
| 7423244 | Baier et al. | Sep 2008 | B2 |
| 7425690 | Schilling | Sep 2008 | B2 |
| 7759616 | Gouardo et al. | Jul 2010 | B2 |
| 20010025848 | Cornec et al. | Oct 2001 | A1 |
| 20020053563 | Pastore et al. | May 2002 | A1 |
| 20030071031 | Gerola et al. | Apr 2003 | A1 |
| 20040238524 | Lerner | Dec 2004 | A1 |
| 20050199614 | Uchida et al. | Sep 2005 | A1 |
| 20070164017 | Gouardo et al. | Jul 2007 | A1 |
| Number | Date | Country |
|---|---|---|
| 2 758 994 | Aug 1998 | FR |
| 2 863 039 | Jun 2005 | FR |
| WO 2005064992 | Jul 2005 | WO |
| Entry |
|---|
| Machine Translation of WO 2005/064992 A1 Description. |
| Machine Translation of WO 2005/064992 A1 Claims. |
| Number | Date | Country | |
|---|---|---|---|
| 20090008384 A1 | Jan 2009 | US |
