Induction hob and method for controlling an induction hob

Abstract

An induction hob has a hob plate, a plurality of induction heating coils arranged under the hob plate and a plurality of sensor coils arranged under the hob plate. The induction heating coils are rectangular, wherein at least two induction heating coils are arranged one behind the other and at least three induction heating coils are arranged one next to the other. Two adjacent induction heating coils form an adjacent region with one another in which the two induction heating coils lie with their adjacent sides. At least one sensor coil is arranged in each adjacent region, wherein precisely a single sensor coil is provided in a spacing direction from the one induction heating coil to the adjacent induction heating coil.

Claims

1. An induction hob comprising: a hob plate; a plurality of induction heating coils arranged under said hob plate; and a plurality of sensor coils arranged under said hob plate, said plurality of sensor coils being wound with turns running in a single and common plane, said single and common plane being above a location of said plurality of induction heating coils, wherein: said induction heating coils are embodied to be rectangular or approximately rectangular; at least two of said induction heating coils are arranged one behind the other and at least three of said induction heating coils are arranged one next to the other; two adjacent of said induction heating coils form an adjacent region with one another, wherein said two induction heating coils lie with sides adjacent to each other in said adjacent region; at least one sensor coil is arranged in each said adjacent region; and precisely one single of said sensor coils is provided in a spacing direction from one of said induction heating coils to adjacent one of said induction heating coils.

2. The induction hob according to claim 1, wherein at least two said sensor coils are provided one next to another along said adjacent sides of said induction heating coils in at least one said adjacent region.

3. The induction hob according to claim 1, wherein a centre point of one of said sensor coils lies between two of said adjacent sides of said induction heating coils.

4. The induction hob according to claim 1, wherein one of said sensor coils is arranged above a central region of one of said induction heating coils.

5. The induction hob according to claim 1, wherein all said induction heating coils are embodied so as to be of equal size.

6. The induction hob according to claim 1, wherein all said induction heating coils have a same winding direction.

7. The induction hob according to claim 1, wherein precisely one single sensor coil is arranged in adjacent regions on two of said induction heating coils being arranged with their short sides adjacent to one another.

8. The induction hob according to claim 7, wherein precisely two sensor coils are provided in adjacent regions between two induction heating coils being arranged with their long sides adjacent to one another.

9. The induction hob according to claim 1, wherein said sensor coils are not distributed uniformly or symmetrically along said long sides, but rather are shifted towards a central region of said induction hob, and away from an edge of said induction hob.

10. The induction hob according to claim 1, wherein, in adjacent regions between two of said adjacent induction heating coils in which only single of said sensor coils is provided, said sensor coil is arranged centrally with respect to said longitudinal sides of said induction heating coil running in said adjacent regions.

11. The induction hob according to claim 1, wherein said sensor coils have a round shape.

12. The induction hob according to claim 11, wherein said sensor coils have ten to forty turns.

13. The induction hob according to claim 1, wherein said sensor coils overlap said induction heating coils uniformly and to a same degree in the same way.

14. The induction hob according to claim 1, wherein said induction heating coils have a single layer of turns, or said turns run in a single layer.

15. The induction hob according to claim 1, wherein said sensor coils are wound in a single layer and turns of said sensor coils run in a single layer.

16. The induction hob according to claim 1, wherein said sensor coils are provided with a temperature sensor in their central area.

17. The induction hob according to claim 16, wherein said temperature sensor is a temperature dependent resistor.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) Exemplary embodiments of the invention are illustrated schematically in the drawings and will be explained in more detail below. In the drawings:

(2) FIG. 1 shows a plan view of an induction hob according to the invention with the hob plate removed; and

(3) FIG. 2 shows a view of various configurations of pans on the induction hob from FIG. 1.

DETAILED DESCRIPTION

(4) FIG. 1 shows an inventive induction hob 11 in a plan view, but with the hob plate removed, or without a hob plate, that is to say therefore a substructure 12. This substructure 12 can, as is shown, be connected to a hob plate essentially in a customary fashion. For this purpose, the substructure 12 has a carrier plate 13 which is then connected to the actual hob plate by securing means or the like.

(5) Eight essentially rectangular induction heating coils 15a to 15h are arranged on the carrier plate 13. The induction heating coils 15 are all embodied identically and oriented in the same way, as can be detected at least in their central region at the point where a respective coil turn 19a to 19h leads off downwards to the electrical connection. The induction heating coils 15 each have long sides 16a to 16h and short sides 17a to 17h. At the corners they are somewhat rounded because of the better guidance of the outer coil turns 19, since they should not be bent. Nevertheless, induction heating coils with this shape will be considered below to be rectangular or at least approximately rectangular, as explained at the beginning.

(6) Ferrite rods 20a to 20h are placed above the coil turns 19a to 19h. The coil turns 19a to 19h themselves are applied to coil carriers 21a to 21h, and these coil carriers 21 are then in turn arranged on the carrier plate 13.

(7) It is apparent that the induction heating coils 15a to 15h are each at a certain distance from their adjacent coils, which distance can in practice be 1 cm to 3 cm or even 5 cm, wherein smaller distances are preferred. As a result, adjacent regions 23 are formed, typically adjacent regions between long sides 16 of the induction heating coils, specifically the adjacent regions 23ab, 23bc, 23cd, 23ef, 23fg and 23gh. These adjacent regions 23 are all of the same width and same length. Furthermore, the induction heating coils 15 form further adjacent regions, specifically the adjacent regions 23ae, 23bf, 23cg and 23dh at their short sides 17 which point towards one another or are adjacent. These four adjacent regions are also each of equal length and equal width. In the exemplary embodiment illustrated here they are somewhat wider than the long adjacent regions, but this does not play any large role.

(8) Sensor coils 25 are arranged in the adjacent regions 23. These sensor coils 25 are embodied as described at the beginning, that is to say flat, single-turn or single-layer coils with a round shape with 10 turns to 30 turns. In each case two such sensor coils 25 are arranged in the long adjacent regions, specifically the sensor coils 25ab, 25ab, 25bc, 25bc, 25cd and 25cd are arranged in the upper three long adjacent regions 23ab, 23bc and 23cd. In the three lower long adjacent regions 23ef, 23fg and 23gh, these are the sensor coils 25ef, 25ef, 25fg, 25fg, 25gh and 25gh. In the case of these sensor coils 25 which are arranged in the long adjacent regions it is apparent that their centre point is arranged in each case precisely in the centre of the adjacent regions 23 or precisely between the adjacent induction heating coils 15 or their long sides 16. Otherwise, the sensor coils 25 overlap the induction heating coils 15 at their long sides 16, in each case by a certain amount, and specifically in the same way. There can be, in practice, one to three or four coil turns 19. Furthermore, although the sensor coils 25 in the long adjacent regions are arranged mirror-symmetrically with respect to an axis through the short adjacent regions, it is apparent that, for example in the upper region of the induction hob 11, the upper sensor coil 25ab is arranged further from the upper short sides 17a and 17b of the induction heating coils 15a and 15b than the lower sensor coil 25ab is arranged from the lower short sides 17a and 17b. This difference can be several cm, but is clear. The shifting can be by several cm, for example 1 cm to 5 cm. Therefore, as mentioned at the beginning, the sensor coil density or detection accuracy in the central region of the entire induction hob 11 is improved compared to the upper and lower edge regions.

(9) Sensor coils 25 are also arranged in the short adjacent regions 23ae, 23bf, 23cg and 23dh. These are also arranged precisely along a central longitudinal axis of the short adjacent regions, that is to say the respective upper and the respective lower induction heating coils 15 overlap uniformly, for example likewise with one to three coil turns. These sensor coils 25 also have a short offset from the central arrangement with respect to the induction heating coils, and the sensor coils 25ae and 25cg are therefore shifted somewhat to the left from the centre point of the short sides 17 of the respective adjacent induction heating coils 15. This shifting may have been by approximately 1 cm. The sensor coils 25bf and 25dh are, in contrast, shifted to the right by the same amount. This has also proven advantageous for the detection of placed pans within the scope of the invention.

(10) Finally, sensor coils, specifically the sensor coils 25a, 25b, 25c, 25d, 25e, 25f, 25g and 25h, are also arranged in central regions of the induction heating coils 15. These sensor coils 25a, 25b, 25c, 25d, 25e, 25f, 25g and 25h are arranged oriented centrally with respect to the long sides 16 of the induction heating coils, but are shifted a small amount to the left or to the right from the centre of the short sides 17 in a way corresponding to the sensor coils 25ae, 25bf, 25cg and 25dh in the short adjacent regions 23.

(11) All the sensor coils 25 are connected to a controller (not illustrated here) of the induction hob 11. A method for actuating the controller will be explained below. In the centre of the sensor coils, the above-mentioned temperature sensors are provided on their top side, shown as small circles. They can be for example PT 1000 temperature dependent resistors. The temperature sensor can be connected to a controller of the induction hob 11.

(12) In the front region, the induction hob 11 has an operator region 27 with displays and operator control elements for setting the power for hobs, which are formed in various ways by one or more induction heating coils 15.

(13) A plurality of possibilities for placed pans are illustrated in FIG. 2. A very large pan 29a is placed in the left-hand upper region, a medium-sized pan 29b is placed in the front central region and a small pan 29c is placed on the right at the top.

(14) The pan 29a covers large regions of the induction heating coils 15a and 15b as well as small regions of the lower induction heating coils 15e and 15f. Furthermore, the sensor coils 25ab, 25ab, 25ef, 25ae and 25bf as well as 25a and 25b are fully covered. This means that these sensor coils primarily detect the presence of a placed pan above them. However, they do not detect that this pan is a single, as it were coherent pan which is to be heated jointly with the same heating power. For this reason, the coverage information of the induction heating coils 15 is also used. Since none of the sensor coils 25e or 25ef which is otherwise also associated with the induction heating coil 15e detects the presence of a pan above it, but at the same time the sensor coils 25fg and 25fg detect the presence of the central pan 29b, which explains the higher degree of coverage of the induction heating coil 15f, a controller of the induction hob 11 can conclude that just such a very large pan is placed and covers these seven sensor coils, that is to say it must be approximately the size of the large pan 29a. In this case, owing to the excessively small coverage of the lower induction heating coil 15a the latter is then not operated, nor is the adjacent induction heating coil 15f. The pan 29a is therefore heated only by means of the two upper induction heating coils 15a and 15b. Here, under certain circumstances the information could also even be output to an operator that the pan 29a should be shifted somewhat more over the two upper induction heating coils 15a and 15b so that it is heated more uniformly. However, this is an optional additional function. Conclusions about the pan material can also be drawn through more wide-ranging evaluation of the sensor signal.

(15) Owing to the wide-ranging coverage of the induction heating coil 15g with complete coverage of the sensor coils 25g, 25fg and 25fg as well as the partial coverage of the sensor coil 25gh without coverage of the sensor coils 25gh and 25g as well as 25e, it is possible to infer the size of the pan 29b. Furthermore, the controller can also detect that this pan 29b partially projects over the induction heating coil 15e. Since the controller can, however, detect on the basis of the size and the arrangement of the pan 29a that the induction heating coil 15f is covered precisely to the same extent by the pan 29a as the induction coil 15e, it can detect that the overall, somewhat larger coverage of the induction heating coil 15f additionally occurs as a result of a part of the further pan 29b, but this portion is in turn too small to justify heating by the induction heating coil 15f. For this reason, the pan 29b is heated only with the induction heating coil 15g. Nevertheless, it is apparent that the overall degree of coverage of the induction heating coil 15f could in itself be sufficient to start a heating operation for a supposedly placed pan.

(16) The induction heating coil 15d detects coverage of approximately 30% to 40%. At the same time, the sensor coils 25d, 25cd and 25dh detect a partial coverage. However, the induction heating coils 15c and 15h do not have any coverage at all. It is therefore apparent that a pan is positioned only over the induction heating coil 15d, and also that its approximate size can be detected. Since such small pans are also to be heated inductively with the induction hob 11, the induction heating coil 15d then actually starts the heating operation for the pan 29c with a power level which is input at the operator region 27.

(17) From FIG. 2 it is apparent, on the basis of the explanation relating to the large pan 29a top left, that the coverage information of the induction heating coils 15, on the one hand, and of the affected sensor coils 25, on the other, necessarily signifies the presence of a single pan, and also approximately with this size. If the pan 29a were even larger with the same placed centre point, it would very quickly cover the sensor coil 25bc and therefore give rise to a signal at it. If it were even larger, but, as it were, shifted somewhat to the left and upwards, so that its degree of coverage of the induction heating coils 15a and 15b would be larger, this would still signify the same heating mode, specifically only by means of the induction heating coils 15a and 15b, which then together form a cooking zone for this pan. If the pan 29a were not circular but instead elongate in the manner of a roasting pan, it could only be larger without coverage of additional sensor coils 25 in the downwards direction, that is to say to a greater extent over the induction heating coils 15e and 15f. However, its degree of coverage would then increase or one of the sensor coils 25e, 25f or 25ef would detect the presence of a pan above it. If a certain degree of coverage of the induction heating coils is reached, or at the latest when one of the specified sensor coils is covered, additional operation of the induction heating coils 15e and 15f would, however, then also be justified.

(18) Furthermore, it is, for example, also clearly apparent that the coverage of the sensor coil 25ef in the case of such small coverage of the induction heating coils 15e and 15f as well as of the sensor coils 25ae and 25bf necessarily means that the sensor coil 25ef is covered by the same pan. Although the coverage with a very small pan, placed essentially centrally over the sensor coil 25ef, would in principle also be possible, the sensor coils 25ae and 25bf could then no longer be covered, unless, in turn, by very small pans. However, given coverage of the other four sensor coils by the pan 29a, this would then again not justify the overall large degree of coverage on the induction heating coils 15a and 15b. Furthermore, as explained at the beginning, all the coverage information of all the induction heating coils 15 and all the sensor coils 25 is continuously evaluated, and the additional degree of coverage of the induction heating coil 15f caused by the pan 29b can also be explained by the detection of this pan.

(19) Furthermore it is also apparent that the coverage by the two pans 29a and 29b cannot take place by means of a single large pan. Otherwise, the coverage of the induction heating coil 15f would be larger, and also the induction heating coil 15c would have to have at least a small degree of coverage, as would also in particular the sensor coils 25bc and 25f, but they are not covered at all. The same also applies to the sensor coil 25cg.