EP1967044B1 - Variable-size induction heating plate - Google Patents

Description

The present invention relates to an induction cooker of variable size, and an induction cooktop incorporating such a hearth.

In general, the present invention applies to the field of domestic cooking appliances by induction, such as induction glass-ceramic tables.

An induction cooking hearth generally consists of a circular winding adapted to the size of a cooking vessel of given size.

It may also consist of several concentric coils to adapt to the different diameters of the containers arranged on the hob above the fireplace.

A cooking hearth may also consist of several coils arranged side by side and supplied by independent generators as described in the patent application. FR 2 758 994 .

Hobs are also known comprising several small coils arranged in a hob. Such a hob is described in particular in the document FR 2 863 039 . This document describes a set of circular coils arranged side by side so as to cover the entire surface of the hob. In this method of assembly, the coils are magnetically independent and are controlled independently so that each cooking focus is determined case by case, depending on the position of the container on the cooking surface, vis-à-vis -vis reels.

However, depending on the position of the container on the hob, it is not uncommon for a large proportion of a group of coils is not covered by the container, so that the power delivered by the inductor is weak.

Indeed, the power delivered by a determined cooking point depends on the electromagnetic adaptation between the inductor and the container disposed above. The container is considered as a resistive load by the current generator supplying the inductor. In principle, the induction heaters are designed such that the electromagnetic adaptation is optimal and the power delivered is maximum when the container completely covers the surface of the inductor.

The present invention aims to solve the aforementioned drawbacks and to provide a cooking induction cooking of variable size to ensure a high power delivered to a container regardless of its size.

To this end, the present invention relates to a variable size induction cooking furnace comprising at least two assemblies of several coils arranged side by side in a plane, each assembly of several coils being adapted to form a cooking chamber.

According to the invention, the firing chamber comprises control means adapted, on the one hand, to independently control said assemblies in operation, and on the other hand to control said assemblies in synchronous operation, each assembly being powered by a single current generator.

Thus, the induction cooking stove has the advantage of being able to function as two independent cooking heaters of medium size or as a single larger sized hearth.

Through the use of several coils in each assembly constituting a cooking hearth, the recovery rate of the surface of the inductor coils is very important, when a container is placed above the two assemblies.

According to an advantageous characteristic of the invention, the assemblies comprise an identical number of coils.

Preferably, the coils of each assembly are tangent to a circle corresponding to the dimension of the cooking zone associated with this assembly, well suited to the circular shape of a conventional cooking vessel.

In addition, each assembly comprises at least three coils equidistant from each other, to distribute well in the plane of the cooking chamber the surface covered by the inductor coils arranged facing the bottom of a container.

Thanks to this equidistant arrangement of the coils, the recovery rate of the bottom of a container placed above three equidistant coils is greater than 70%.

According to one embodiment, the cooking chamber comprises two assemblies, each assembly comprising at least three coils equidistant from each other, at least two coils of a first assembly being arranged facing each other or at least two coils of a second assembly.

This arrangement provides a wider cooking focus at its center, well suited to heat larger containers when the coil assemblies operate in synchronized mode.

In addition, the surface of the inductors covered by a container placed in the center of the two assemblies is greater than 50% with a container of such size that it completely covers an assembly of inductor coils. Furthermore, the bottom surface of a container placed next to the coils of an assembly represents at least 70% of the total surface of the bottom of the container.

Preferably, the coils of each assembly are tangent to an ellipse corresponding to the size of a single large size cooking chamber.

The present invention also relates to an induction hob, comprising a cooking stove according to the invention.

This cooktop has features and benefits similar to those previously described in connection with the cooking stove.

Other features and advantages of the invention will become apparent in the description below.

• la figure 1 est un schéma simplifié illustrant un foyer de cuisson par induction conforme à un mode de réalisation de la présente invention ;
• la figure 2 est un schéma illustrant un assemblage de bobines du foyer de cuisson de la figure 1 ;
• la figure 3 est un schéma illustrant le fonctionnement en deux foyers indépendants du foyer de cuisson de la figure 1 ;
• la figure 4 est un schéma illustrant le fonctionnement en un unique foyer du foyer de cuisson de la figure 1 ; et
• les figures 5 et 6 sont des schémas illustrant des foyers de cuisson par induction conformes à d'autres modes de réalisation de l'invention.

In the accompanying drawings given as non-limiting examples:

• the figure 1 is a schematic diagram illustrating an induction cooking hearth according to an embodiment of the present invention;
• the figure 2 is a diagram illustrating a coil assembly of the cooking hearth of the figure 1 ;
• the figure 3 is a diagram illustrating the operation in two independent homes of the cooking chamber of the figure 1 ;
• the figure 4 is a diagram illustrating the operation in a single focus of the cooking hearth of the figure 1 ; and
• the Figures 5 and 6 are diagrams illustrating induction cooking stoves in accordance with other embodiments of the invention.

We will now describe with reference to Figures 1 to 4 , an embodiment of an induction cooking stove according to the invention.

In this embodiment, the cooking chamber comprises two assemblies 10, 10 'of several coils 10a, 10b, 10c, 10'a, 10'b and 10'c, all deposited in a plane parallel to the cooking surface.

As well illustrated on the figure 2 each assembly 10, 10 'comprises three coils arranged in a triangle, such that each assembly 10, 10' comprises coils equidistant from each other.

Thus, each assembly 10, 10 'of three coils is inscribed in a circle, as illustrated in FIG. figure 2 , so as to constitute a disk-shaped cooking hearth particularly well adapted to the shape of a cooking vessel.

In this embodiment, the coils are disk-shaped and tangent to the circle defining the cooking zone.

Each coil consists of an electrically conductive winding.

In practice, each coil may consist of a spiral flat winding of a multi-strand strand of copper wires.

The electrically conductive windings of each coil are non-parallel to the electrically conductive windings of neighboring coils. Thus, the natural magnetic coupling between two neighboring coils is virtually zero.

Furthermore, the two coil assemblies are arranged side by side in a plane parallel to the cooking plane and are inscribed substantially in an oval or elliptical shape.

In practice, each assembly 10, 10 'comprises two coils 10a, 10b and 10'a, 10'b disposed facing each other and equidistant from each other.

As illustrated in figure 1 each assembly 10, 10 'is fed by a single high-frequency alternating current generator 11, 11' conventionally used for supplying induction heating coils. The three coils of each assembly 10, 10 'are electrically connected in series or in parallel with each generator 11, 11'.

Preferably, the coils of each assembly 10, 10 'are electrically connected in series with each generator 11, 11'. Thus, unlike a parallel assembly, it is possible to avoid overheating of a coil that would not be covered by a small container placed on the assembly.

Control means 12, 12 'make it possible to operate in two configurations.

When the cooking hobs formed by each assembly 10, 10 'are used independently, as illustrated for example in FIG. figure 3 , the control means 12, 12 'are adapted to independently control the operation of each generator 11, 11', thus ensuring the operation of the two cooking stoves independently.

On the other hand, when the cooking stove is used as a single fireplace to heat a larger container, as illustrated in figure 4 , the control means 12, 12 'are adapted to synchronously control, thanks to a synchronization module 13, the operation of the generators 11, 11' so as to allow the operation of the six coils 10a, 10b, 10c, 10 ' a, 10'b and 10'c synchronously.

In practice, and by way of nonlimiting example, the diameter of each inductor coil 10a, 10b, 10c, 10'a, 10'b, 10'c is equal to about 100 mm. Each assembly 10, 10 'of three coils arranged in a triangle is then inscribed in a circle of about 200 mm, which corresponds to a focus of medium size.

The juxtaposition of the two assemblies 10, 10 'in two opposite triangular arrangements allows for a cooking zone of about 200 mm wide and 400 mm long.

The cooking stove of variable size thus offers the possibility of using two cooking hobs independent of each other, each constituted by three coils of each assembly 10, 10 ', a middle central circular fireplace consisting of four coils 10a, 10b, 10'a, 10'b controlled synchronously, or a large elliptical focus consisting of six coils 10a, 10b, 10c, 10'a, 10'b, 10'c, controlled synchronously .

Thus, such a variable size cooking hearth allows on the one hand to accept one or two small containers, of the order of 12 to 20 cm in diameter, arranged side by side, and on the other hand to receive a container of medium size, of the order of 25 cm in diameter, or even a large oval container, up to 40 cm long.

As well illustrated on the figure 4 thanks to the use of elementary coils in each assembly 10, 10 ', a medium-sized container disposed in the center of the cooking chamber is adapted to cover about 60% of the surface of the inductor coils.

Note that if each assembly 10, 10 'was replaced by a single circular inductor of diameter substantially equal to 200 mm, the same container would cover only about 40% of the surface of the inductors.

Thus, the induction cooking stove according to the invention makes it possible to optimize the area covered by the inductors by a container of any size, and thus to guarantee a high operating power in the various cases of use of the fireplace. cooking.

Furthermore, it is important that the total area covered by the inductor coils disposed under the bottom of the container is the largest possible to ensure a good temperature distribution in the container.

By using small elementary coils, it is possible to better distribute the surface of the coils arranged vis-à-vis the bottom of the container, and thus ensure a good distribution of the heating of the container.

Thus, thanks to the triangle arrangement of three coils under the bottom of a container whose diameter substantially corresponds to the dimension of the circle tangential to the three coils, the recovery rate of the bottom of the container by the inductor coils is greater than 70% .

Of course, the shape and the number of coils of each assembly of the variable size cooking stove are not limited.

Illustrative non-limiting examples of other examples of cooking hearth according to the invention on Figures 5 and 6 , in which the neighboring coils of each assembly are also nested and arranged in staggered relation to each other.

So, on the figure 5 each assembly 10, 10 'respectively comprises five coils 10a-10e, 10'a-10'e. In each assembly 10, 10 ', the inductor coils are arranged in staggered rows. Furthermore, each assembly 10, 10 'comprises three coils 10a, 10b, 10c and 10'a, 10'b, 10'c disposed opposite each other and equidistant from each other.

As illustrated in figure 6 , according to another embodiment, each assembly 10, 10 'comprises six coils 10a-10f, 10'a-10'f. In each assembly 10, 10 ', the coils are staggered and form a base triangle consisting of three coils 10a, 10b, 10c and 10'a, 10'b, 10'c and having a single coil 10f, 10' f at the top.

It is thus possible to obtain foci of variable sizes and of variable shapes, for example round, oval or other.

This gives a cooking stove of variable size to equip an induction cooktop with great flexibility of use depending on the size of the cooking vessels.

Of course, the present invention is not limited to the embodiments described above.

Thus, the cooking chamber could comprise assemblies of coils different from each other.

Furthermore, the cooking chamber could comprise a greater number of coil assemblies, and for example three assemblies.

Finally, the shape of the coils is not limited to one form of disc, but may be different and for example oval or other.

Claims (8)

1. Variable-size induction heating plate comprising at least two sets (10, 10') of a plurality of windings (10a-10f, 10'a-10'f) disposed side by side in a plane, each set (10, 10') of a plurality of windings being adapted to constitute a heating plate, characterized in that it comprises control means (12, 12', 13) adapted on the one hand to control said sets for independent operation and on the other hand to control said sets for synchronous operation (10, 10'), each set (10, 10') of a plurality of windings being supplied with power by a single current generator (11, 11').
2. Heating plate according to claim 1, characterized in that the windings of each set (10, 10') are electrically connected in series with said current generator (11, 11').
3. Heating plate according to either of claims 1 or 2, characterized in that said sets (10; 10') include exactly the same number of windings (10a-10f, 10'a-10'f).
4. Heating plate according to any one of claims 1 to 3, characterized in that the windings of each set (10; 10') are tangential to a circle corresponding to the dimension of said heating plate associated with each set.
5. Heating plate according to any one of claims 1 to 4, characterized in that each set (10; 10') includes at least three equidistant windings (10a, 10b, 10c; 10'a, 10'b, 10'c).
6. Heating plate according to any one of claims 1 to 5, characterized in that it comprises two sets (10, 10'), each set (10, 10') including at least three equidistant windings (10a, 10b, 10c; 10'a, 10'b, 10'c), at least two windings (10a, 10b) of a first set (10) being disposed face to face with at least two respective windings (10'a, 10'b) of a second set (10').
7. Heating plate according to any one of claims 1 to 6, characterized in that the windings of each set (10; 10') are tangential to an ellipse corresponding to the dimension of a single large heating plate.
8. Induction cooking surface, characterized in that it comprises a heating plate according to any one of claims 1 to 7.

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