cooktop

Abstract

Cooktop (211) with a cooktop plate (212) as a cover and with at least one heating device (213) underneath, wherein the heating device (213) comprises: - a carrier (215), - at least one heating element (220), wherein the heating element o is located under the cooktop plate (212) and above the support (215), o has a boundary (221), o is movable on the carrier (215), wherein: - at least two thermally activated actuators (225) per heating element (220) are provided on and / or within the heating device (213) for the heating element (220) in order to move it within the heating device above the support (215), - the thermally activatable actuators (225) are designed such that they project laterally in a direction parallel to the plane of movement of the heating element (220) at least partially beyond it, - the thermally activatable actuators (225) are designed and attached to the heating element (220) in such a way that a thermally activatable actuator (225) supplied with radiant heat (S) from above moves the heating element (220) in such a way that the radiant heat (S) in the thermally activatable actuator (225) decreases, characterized in that the thermally activatable actuators (225) are arranged in a plane below the heating element (220), being arranged partly below and partly outside the edge boundary (221) of the heating element.

Description

Area of ​​application and state of the art

[0001] The invention relates to a hob with a hob plate and a heating device underneath according to the preamble of claim 1.

[0002] In the case of cooktops with a cooktop plate as a cover and several heating devices underneath, a cooking vessel placed on the cooktop plate can, if it is of the right size, be heated by exactly one of these heating devices. The type of heating can vary, for example using so-called radiant heating devices or induction coils. A general difficulty here is that a cooking vessel is not always placed exactly centrally over a heating device. This can lead to less efficient heating, longer heating times and higher energy consumption, which is considered disadvantageous, particularly when using radiant heating devices. DE 10 2015 203 316 A1 and DE 10 2016 218 269 A1 describe ways in which induction coils or heating devices in general can be moved into the most suitable position possible under a cooking vessel on the cooktop plate above.However, these solutions are very complex in terms of position detection, control mechanics, and activation. It would be desirable to have a simpler method with a simpler cooktop structure.

[0003] US 2019 / 0254124 A1 discloses a cooktop comprising multiple heating elements beneath a cooktop plate. The heating elements can be moved more effectively and centrally beneath a cooking vessel placed on the cooktop plate by means of bimetallic elements engaging with them. The bimetallic elements extend radially along a circular heating element in a base position. They also extend above the heating element, allowing them to be exposed to maximum radiant heat from above.

[0004] DE 10 2006 025 095 A1 discloses the use of hydrogel, for example, for valves, pumps, sensors, or actuators. The hydrogel is arranged in a chamber whose volume can be adjusted. A housing of the chamber can be divided into two parts and can have at least one elastically deformable membrane wall, which can be semipermeable. Task and solution

[0005] The invention is based on the object of creating a cooking hob as mentioned above, with which problems of the prior art can be solved and, in particular, it is possible to adapt the position of a heating device to the position of a cooking vessel placed above it on a cooking hob plate as simply and practically as possible.

[0006] This object is achieved by a hob having the features of claim 1. Advantageous and preferred embodiments of the invention are the subject of the further claims and are explained in more detail below. The wording of the claims is incorporated into the content of the description by express reference.

[0007] The hob is provided with a hob plate as a cover and at least one heating device underneath. The heating device, in turn, has a support and at least one heating element arranged above the support and below the hob plate. Advantageously, the heating element can rest on the support and be movable thereon. Bearing means or friction-reducing devices such as sliding projections made of a suitable material, wheels, or the like can be provided here. The heating element has an edge limitation, advantageously designed as a solid edge or border. Advantageously, the heating element is provided with a flat design or with a flat heating effect, for example as a conventional radiant heating device according to EP 590315 A2 or as an induction heating coil according to EP 1686836 A1. The heating element is preferably round or circular, although other shapes such as oval or rectangular are also possible.

[0008] According to the invention, thermally activatable or actuatable or triggerable actuators are provided on or within the heating device, which move the heating element within the heating device on or above the support. The thermally activatable actuators can engage the heating element or be attached to it in order to be able to move it. The thermally activatable actuators are designed such that they at least partially protrude laterally beyond the heating element in a direction parallel to the plane of movement of the heating element. This partial protrusion can advantageously be such that at least one of the thermally activatable actuators protrudes laterally beyond the heating element and is thus visible and accessible in a plan view from above, in particular for radiant heat from above. Depending on the position of the heating element, this can apply differently to different actuators.Furthermore, the thermally activated actuators are distributed across the heating element, advantageously evenly distributed. At least two thermally activated actuators are provided per heating element, advantageously more, such as four, six, or eight. The thermally activated actuators are attached to the heating element in such a way that a thermally activated actuator exposed to radiant heat from above moves the heating element in such a way that the radiant heat or the input of radiant heat into the thermally activated actuator is reduced. This radiant heat advantageously emanates from a cooking vessel placed on the cooktop, which is heated by the activated heating device or the activated heating element and thus has a hotter base. This radiates a considerable amount of radiant heat downwards, particularly at temperatures of around 100°C, advantageously above 200°C.This radiant heat passes through the hob plate, and if the cooking vessel protrudes laterally over the heating element with part of its base because the positioning or overlap is not optimal, this protruding area heats up downwards or radiates radiant heat downwards. This heat then hits the thermally activatable actuator, which protrudes laterally from the heating element or protrudes over the heating element, in particular from underneath it, so that the actuator becomes hotter here. In particular, the thermally activatable actuator arranged in this protruding area becomes hotter than other actuators attached to the heating element, in particular than actuators arranged directly opposite or in an area opposite each other. According to the invention, the thermally activatable actuator is designed such that it then moves the heating element in such a way that less radiant heat is radiated into it.This can be achieved primarily by an actuator located beneath the heating element, which moves the heating element even further above itself, thus automatically moving it in the direction of the radiant heat from above, i.e., in the direction where the cooking vessel protrudes above the heating element. This automatically brings the cooking vessel and heating element into better overlap, or rather, better centered relative to each other. If the actuator is mounted on the outside of the heating element, particularly at one of its edges, it moves the heating element and itself in the direction of better overlap between the cooking vessel and heating element, which essentially has the same effect.

[0009] In the context of this application, better coverage means that the distance between the center of the surface of the cooking vessel or its base and the center of the surface of the heating element is reduced and as small as possible overall. This improves the heating of this cooking vessel by means of this heating element, or can be optimized.

[0010] The thermally activated actuator is advantageously designed as a passive actuator. This means that it does not require an external power supply. It is also particularly advantageous in that it does not have any sensors that need to be evaluated. This makes the structure noticeably simpler. Furthermore, it is particularly advantageous to have an automatically operating actuator that requires neither a power supply nor control by a special controller or the like. When exposed to radiant heat, i.e. when heated, it works automatically, so to speak, until it reaches a state in which it either no longer receives any radiant heat that would deform it, or until identical actuators arranged directly opposite or in an opposite area build up a sufficiently strong counterforce that counteracts the force developed by the actuator so strongly that it can no longer move the heating element. By omitting the control system and sensors and a separate orWith its own power supply for the actuators, the design is noticeably simple, which reduces costs and increases reliability.

[0011] In an advantageous embodiment of the invention, the thermally activatable actuators are arranged in a uniform distribution, in particular at the same distance from one another or offset at the same angle to one another. Such a regular arrangement has the great advantage that not only is a larger number of actuators provided overall, which can apply sufficient force to move the heating element as desired for better coverage with a cooking vessel placed on top, but also that a better distribution of the thermally activatable actuators can result in more precise movement to create better coverage. Depending on the type of thermally activatable actuators, as will be explained in more detail later, a large number of such actuators, in particular 20 to 30, can be provided around the heating element and thus heated very evenly with radiant heat from a projection on the base of the cooking vessel in order to then move the heating element.

[0012] In the invention, it can advantageously be provided that thermally activatable actuators, which are acted upon by radiant heat from above and are then intended to move or pull the heating element in this direction, have thermally activatable actuators on the other side of the heating element, which then experience a change in length or which, so to speak, release the heating element and enable its movement towards the projection. This can be facilitated by these thermally activatable actuators being an above-average distance from the heating element and, above all, from the cooking vessel as the source of radiant heat, and are thus significantly cooler than those actuators below the area of ​​radiant heat from above. Thus, they can, so to speak, enable or allow the heating element to move away from them; under certain circumstances, as will be explained in more detail below, they can even support such a movement.

[0013] According to the invention, the thermally activated actuators are arranged at least partially or in regions in a plane below the heating element. They are arranged at least partially outside the edge of the heating element or protrude laterally outwards below the heating element. This is then the area into which radiant heat can radiate from above to heat this area so that the actuator can be thermally activated and move the heating element as intended. Such actuators can, so to speak, capture radiant heat with their laterally projecting part and then transmit it to an area of ​​them located below the heating element. Materials with good thermal conductivity are suitable for this purpose.This makes it possible for a thermally induced change in the actuator's material to be effective not only in the potentially relatively small area directly exposed to radiant heat from above, but also in a larger area, particularly the largest area of ​​the actuator or the entire actuator. The heat is then distributed within the actuator.

[0014] In an embodiment of the invention, the thermally activatable actuators can be designed to move the heating element by expanding one or more of the materials in question. This follows the normal law that most materials expand or increase in volume when heated, i.e. they have a positive thermal expansion coefficient. As a result of this expansion, the thermally activatable actuator can move the heating element, in particular to ensure better coverage with a cooking vessel placed on top of it, or in such a way that a center point of the heating element is moved towards the thermally activatable actuator. An actuator can be fastened with one end outside the heating element and at a radial distance from it, and with the other end to the heating element, in particular close to or directly at its edge. Due to its design orIn its design, it must convert the expansion of a material due to heating into a contraction in order to move the heating element toward its radially outwardly mounted end. Alternatively, the thermally activated actuator can generally be made of a material that contracts when heated, i.e., one with a negative thermal expansion coefficient. Then it can move the heating element directly and in a way that is easy to understand, by directly contracting when heated.

[0015] In another embodiment of the invention, the actuator can be elongated and have two ends, one end being arranged below the heating element and offset a little bit radially inwards, for example 1 cm to 5 cm, and is attached to the support below. The end projecting above can then project 2 cm to 4 cm or even 10 cm radially, and from this end a mechanical connection can be made to the heating element or its edge. This long, laterally projecting part can then expand and move its free end away from its other free end, which is attached to the support. In doing so, this free end, through its connection to the heating element, pulls the heating element in the same direction in which the free end expands, thus also enabling movement. This movement can possibly occur against a force exerted by at least one thermally activated actuator in the opposite area.For this purpose, it can be designed to be correspondingly flexible; alternatively, a certain amount of looseness can be provided in the connection between the actuator and the support and / or the heating element. This may, however, make it impossible to achieve a clear base or center position for the heating element. However, this is not absolutely necessary, since the heating element, thanks to the invention, moves as far as possible underneath a set-up and heated cooking vessel, which radiates or introduces radiant heat downwards into at least one thermally activated actuator in an overhang area above the heating element.

[0016] Alternatively, the heating element can have a home position, wherein in this home position it is arranged centrally in the heating device or in an edge of the support. From there, it can be moved into various deflection positions, wherein a deflection position is precisely a position in which the heating element has been moved from the home position towards a projection of a cooking vessel. The heating element can possibly remain in this deflection position, even after the heating element has stopped operating and thus when the cooking vessel is cool again, as long as it is not moved back into another deflection position or into the home position by another thermally activated actuator. The home position enables the heating element to be in a predeterminable position when not in operation, i.e. when it is not exposed to radiant heat from above by a cooking vessel it is heating.

[0017] The aforementioned thermally activated actuators can be selected in various ways, for example, they can comprise an element from the following group, such as expansion elements, bimetallic strips, bipolymer strips, shape memory alloys, thermoactive plastics, or an expansion material. The aforementioned expansion materials can be, for example, oil, wax, hard paraffin, or the like. A thermally activated actuator can be designed in the form of a rod or strip, alternatively as a flexural element, a spring, or a helical spring. A design as a helical spring in particular has the advantage that such a thermally activated actuator can exhibit a certain degree of elasticity, so that it can also be influenced or deformed by other actuators in order to effect a desired movement of the heating element towards a smaller projection of the cooking vessel placed above it.

[0018] A thermally activated actuator, in particular any actuator, can advantageously have a heat irradiation area and a movement area. The heat irradiation area and the movement area can interact in such a way that, as radiant heat increases in the heat irradiation area, the movement area, possibly even the heat irradiation area itself, causes the thermally activated actuator to move or expand, which in turn moves the heating element as desired.

[0019] The thermally activated actuator should be designed and positioned in such a way that the radiant heat is directed into the heat radiation area. The movement area then moves the heating element, and advantageously also the heat radiation area.

[0020] In one embodiment of the invention, the thermally activatable actuator can have a negative thermal expansion coefficient overall. The heat radiation area and the movement area are formed together, in particular by the same component. Alternatively, the heat radiation area and the movement area can be formed together, for example by the same component, but have a positive thermal expansion coefficient. A desired movement of the heating element can then be achieved through their design or construction and / or their attachment to the heating element and the heating device. Reference is also made, in particular, to the following exemplary embodiments and drawings.

[0021] As an alternative to the aforementioned material having a negative thermal expansion coefficient, the thermally activatable actuators may comprise a material, particularly as the movement region or within the movement region, that expands when heated or has a positive thermal expansion coefficient. This is known to apply to most materials, particularly most of those mentioned above. The movement region can convert a movement toward a central region of the heating element into a movement in the opposite direction via a gear, particularly a lever. Such a gear is advantageously attached to the heating element or engages the heating element and moves it in the opposite direction, being moved at least partially over the heat radiation region or increasingly covering it.This means that the movement of the heating element can be stopped again at some point, so to speak, if it is arranged in the previously existing overhang area or if the cooking vessel and heating element are arranged centrally to one another or in a manner that largely or completely overlaps.

[0022] In principle, it can also be regarded as such a gear if a thermally activated actuator is designed as described above and is attached to the support below the heating element with one end and to the heating element with the other, but via a pull rod or pull connection or the like.

[0023] In yet another possible embodiment of the invention, the carrier has a holding limit which surrounds the heating element with its edge limit. In this way, a circumferential annular space can be formed around the heating element, which can have a width in the range between 0.5 cm and 5 cm, advantageously between 1 cm and 4 cm. This annular space should also be formed on the carrier, but this does not have to be the case, in which case the holding limit can also be arranged on the carrier or connected to it. Hydrogel spheres as thermally activated actuators are arranged in this annular space or between the holding limit and the edge limit. The intermediate space or annular space should be watertight or airtight, in particular by seals downwards towards the carrier and upwards towards the underside of a hob plate. The hydrogel spheres should rest against one another, advantageously also at the edge limit and the holding limit.The annular space should therefore be partially or largely, preferably completely, filled with hydrogel spheres, particularly in the radial direction. These hydrogel spheres can advantageously be arranged on or in a single plane, so that it is possible to arrange the hydrogel spheres in a row as a circumferential ring, for example, 10 to 40 such hydrogel spheres. Alternatively, they can be provided as a random bed or the like, in which case advantageously in a significantly larger number with more than 40 hydrogel spheres, particularly advantageously up to 100 or even up to 500 hydrogel spheres.

[0024] These hydrogel spheres have hydrogel inside them or are made of hydrogel. Hydrogel is a material that expands significantly when it absorbs liquid such as water. In the area around the heating element, where there is an overhang caused by a cooking vessel placed above it with radiant heat downwards, the hydrogel spheres become warm or hot due to this radiant heat. This causes any liquid or water stored in them to evaporate, making them smaller. At the same time, this water remains in the enclosed annular space in which the hydrogel spheres are arranged and is absorbed by all the colder hydrogel spheres. The colder the hydrogel spheres are, the more water they absorb, i.e. the exact opposite of the heated hydrogel spheres. As they absorb water, they in turn become larger or expand.If the hydrogel spheres on one side of the heating element shrink or contract due to the overhang of the cooking vessel with radiant heat downwards, and the other hydrogel spheres expand to their maximum on the other side, particularly in the area directly opposite, the expanding hydrogel spheres push the heating element away from them and in the easiest direction, i.e. to where the hot hydrogel spheres have contracted. In this way, the heating element is moved in the direction in which it is as far below the hot cooking vessel as possible, or in which the cooking vessel no longer protrudes over the heating element. If the heating element reaches the stop limit, then the maximum travel distance has been reached. If this is sufficient to achieve good coverage between the cooking vessel and the heating element, then the goal has been achieved.If this isn't sufficient, heating will have to be done with a slight offset. Nevertheless, covering the area and thus heating is definitely better than before.

[0025] The advantage of such hydrogel spheres, which are also presented in the following example, is that they allow for the influencing or modification of many or all thermally activated actuators around the heating element, whereas with the previously described solutions, thermal influence actually only occurs in a few actuators, and then only in those that are heated more strongly. The other actuators, however, remain thermally unaffected.

[0026] In a further advantageous embodiment of the invention, a diameter of a hydrogel sphere can correspond to the distance between the edge boundary of the heating element and the holding boundary of the heating device or the carrier when the heating element is in the aforementioned basic position. Preferably, all hydrogel spheres are of the same size and touch each other laterally. Their diameter can therefore correspond to half the difference between the diameters of the edge boundary and the holding boundary. The hydrogel spheres do not necessarily have to be spherical, i.e., completely rounded. They can also be any desired solid body, whereby a maximum diameter should preferably be no more than three times, advantageously no more than twice, a minimum diameter.

[0027] These and other features emerge not only from the claims but also from the description and the drawings. The individual features may be implemented individually or in combinations in an embodiment of the invention and in other fields, and may represent advantageous and individually protectable embodiments for which protection is claimed here. The division of the application into individual sections and subheadings does not limit the generality of the statements made therein. Brief description of the drawings

[0028] Embodiments of the invention are illustrated in the drawings and explained in more detail below. In the drawings: Fig. 1 a simplified plan view from above of a section of a hob according to the invention with a heating device including a round heating element, above which a pot has been placed offset, Fig. 2 the arrangement Fig. 1, where the heating element has just started heating without any movement, Fig. 3 the arrangement Fig. 2, where the heating element has been moved towards the cooking vessel by thermally activated actuators, Fig. 4 the state after a few minutes, where starting from Fig. 3 the thermally activated actuators have moved the heating element centrally under the hob, Fig. 5 a modification of the heating device according to Fig. 1 with eight thermally activated actuators, Fig. 6 a lateral section through a cooking vessel not according to the invention corresponding to the Fig. 1, in which a cooking vessel is placed on the hob offset from the heating element, Fig. 7 the representation from Fig. 6 in a condition corresponding to Fig. 4, in which the thermally activated actuators moved the heating element centrally under the cooking vessel, Fig. 8 a representation of the invention similar Fig. 6 with a more concretely illustrated thermally activated actuator in rod form, which expands when heated from above into a position shown in dashed lines and thereby moves the heating element, Fig. 9 shows yet another modification of a thermally activated actuator with a spring made of a shape memory alloy in a representation similar to Fig. 8, which is attached to a holding limit and engages the side of the heating element, Fig. 10 the representation from Fig. 9 with heated and expanded actuator, which has moved the heating element at least partially or better centrally to the placed cooking vessel, Fig. 11 is a representation of an alternative embodiment not belonging to the invention, similar Fig. 1 with a view from above with a heating element which is mounted on a support within a holding limit and is surrounded by hydrogel balls, with a cooking vessel placed offset thereon and Fig. 12 the heating device Fig. 11 in a state after several minutes of heating the cooking vessel, where the hydrogel balls have deformed differently and the heating element has moved almost centrally under the cooking vessel. Detailed description of the implementation examples

[0029] In the Fig. 1 shows a section of a cooking hob according to the invention, which will later be shown in the Fig. 6 ff. is shown in a sectional view. The hob 11 has a heating device 13 which has a support 15 and, at the edge of this support 15, a holding limit 16. A round heating element 20 is mounted or arranged on a support surface 18. The heating element 20 can, as explained above, have a different functional principle; advantageously, it is a radiant heating device according to the aforementioned EP 590315 A2 or an induction heating coil according to the aforementioned EP 1686836 A1. The heating element 20 has a circumferential edge 21, advantageously made of stable material. Four actuators 25 are provided which are designed to be thermally activated as described above. They will first be explained in general terms below. The actuators 25 are attached to the edge 21 of the heating element 20 with an inner end. The actuators 25 are attached to the holding limit 16 with an outer end.The actuators 25 are designed in such a way that they contract when heated, i.e., they shorten or their two ends move closer together. Overall, they therefore have a negative thermal expansion coefficient due to their design and / or material. The actuators 25 in the arrangement shown here can thus pull the heating element 20 toward them when heated or exert a tensile force due to their shortening.

[0030] A pot T is placed on a hob plate (not shown here) of the hob 11 as a cooking vessel; it is preferably a completely normal pot. Its outline, or the outline of a pot base, is shown in dashed lines. It can be seen that the pot T is arranged diagonally offset to the top right relative to the heating element 20, so its position is not suitable for optimal or even good heating. A pot of the same size would be a good match for the size of the heating element 20. It can be seen that the pot T, or rather its base, partially covers the upper and right-hand thermally activated actuator 25 due to the overhang here. This will play an important role later. It is relatively far away from the other two actuators 25.

[0031] In the Fig. 2 is the same condition as in Fig. 1, the heating element 20 has begun heating. This depends on its configuration; in any case, the bottom of the pot is heated. Even if, due to the non-centric placement of the pot T above the heating element 20, the bottom of the pot is not evenly heated, particularly in the upper right area, there is no direct heating from below, the heat is distributed fairly evenly in the bottom of the pot. Thus, the upper right area of ​​the pot T or its bottom is also heated, possibly a few °C less than the area directly above the heating element 20, but it still gets hot. Due to its own heating, the bottom of the pot can then emit heat radiation or radiant heat downwards through the hob plate, which visibly radiates into the upper and right thermally activated actuators 25. These are thus heated or thermally activated. They thus shorten, which is reflected in the Fig. 3. By shortening, the two actuators 25 pull the heating element 20 diagonally upwards to the right. The other two unheated actuators 25 can become longer or are pulled apart or stretched by the force of the heated actuators 25.

[0032] From the presentation of the Fig. 3 shows that the heating element 20 is already significantly more fully covered by the pot T. However, it is not yet optimal. Furthermore, it can be seen that the pot T, shown in dashed lines, still directly covers the two actuators 25 above and right, and thus its radiant heat can still affect them. Therefore, they are shortened even further until the representation of the Fig. 4, which thus shows the deflection position mentioned above. The basic position is shown in the Fig. 1 and Fig. 2. Here, the pot T is precisely centered on the heating element 20. Furthermore, the bottom of the pot T covers all actuators 25 approximately evenly, thus heating or thermally activating them approximately evenly. Thus, the left and lower actuators 25 can also experience a certain shortening due to heating, thus building up a counterforce to the actuators above and right, which prevents the heating element 20 from being pulled further upwards and to the right.

[0033] Based on these four illustrations and descriptions, it is easy for the person skilled in the art to understand that even with any other offset or off-centered placement position of the pot T above the heating element 20, the actuators covered in each case, after heating by the hot pot base, try to pull the heating element under the pot T, so to speak, or they actually pull the heating element 20 in the direction of the projecting area of ​​the pot T above the heating element 20 until such a projecting area no longer exists or until the actuators 25 are no longer heated by a projecting area of ​​the pot base or can no longer pull. Alternatively, according to Fig. 4 heating will act on all actuators 25 simultaneously and in the same way, which will then also prevent further movement of the heating element.

[0034] In the Fig. 5 is similar to the Fig. 1 shows how eight thermally activated actuators 125 can be provided in a further heating device 113 of a hob 111. The same parts are designated by the same reference numerals, only preceded by a 1. Fig. 5 shows that, when the pot T is specifically positioned above the heating device 113, the heating element 120 can be particularly well pulled in this direction due to the thermally activated actuator 125 at the top right. The provision of eight thermally activated actuators 125 is therefore in accordance with the design of the Fig. 1 to 4 are preferable, since a better adapted and stronger movement of the heating element is possible through the actuators 125.

[0035] In the sectional view of the Fig. 6 and Fig. 7 is according to the Fig. 2 and Fig. 4 shows what this looks like from the side. The pot T is placed on the hob plate 12 of the hob 11, but laterally offset from the heating element 20 of the heating device 13 in its home position. The heating element 20 rests on the support surface 18 of the support 15 with sliders 22 on its underside. The heating element 20 can rest directly on the underside of the hob plate 12, or alternatively, it can be spaced apart, making it easier to move. Two thermally activated actuators 25 are shown, which are attached by an inner end to an edge 21 of the heating element. The actuators 25 are attached by an outer end to an edge-like holding limit 16 of the support 15.

[0036] In the presentation of the Fig. 6, the heating element 20 begins its heating operation, even if the pot T is clearly not placed centrally or offset from it. The bottom TB of the pot T is thereby heated and in the right in Fig. It then radiates heat downwards into the overhang area shown in Figure 6. This radiant heat S is illustrated by the arrows, where it acts on the actuator 25 located underneath. The actuator 25 then shortens due to its structural design and / or choice of material and pulls the heating element 20 to the right. The force of the shortened actuator 25 on the right lengthens the left actuator 25, allowing the heating element 20 to move. The heating of the pot T by the heating element 20 during heating operation is not shown here; with a radiant heating device, it would also be radiant heat, which would then be similar to that shown, only in reverse.

[0037] While the Fig. 6 shows the basic position of the heating element 20 on the heating device 13, as mentioned above, Fig. 7 shows the maximum deflection position or a deflection position of the heating element 20. The right thermally activated actuator 25 is significantly shortened and has thereby pulled the heating element 20 centrally under the pot T or the pot base TB. As can be seen, the right actuator 25 is thus no longer exposed to radiant heat, or not more intensely, than the left actuator 25, resulting in a kind of force equilibrium.

[0038] In the Fig. Figure 8 shows a further embodiment of a cooktop 211 according to the invention, which has a cooktop plate 212 with a heating device 213 underneath. The heating device 213 has a heating element 220 that can rest against an underside of the cooktop plate 212 and rests with sliders 222 on a support 215 or on its support surface 218. The support 215 has an outer retaining limit 216. The support 215 can be made of sheet metal, for example, or alternatively of plastic. The retaining limit 216 is then bent laterally or pulled upwards.

[0039] A thermally activated actuator 225 is elongated and rod-like. Its inner end 226 is attached to the support surface 218 or to the support 215 by means of a pin 229, which allows a certain degree of rotation. Its outer end 227 has an upwardly projecting pin 231, to which a tension element 232 is attached at one end. The other end of the tension element 232 is connected to the edge 221 of the heating element 220. The tension element 232 can, for example, be a thin rope, a thin wire, or a thin rod, advantageously each made of metal. The attachment of the actuator 225 with the inner end 226 to the pin 229 can advantageously be designed such that the actuator 225 has the illustrated upwardly inclined profile. This makes it possible for the inner end 226 to be mounted below the heating element 220, while the outer end 227 projects laterally far beyond the edge 221 of the heating element 220.Because it slopes upwards, it is closer to the hob plate 212 and thus also closer to a radiant heat source.

[0040] The thermally activated actuator 225 is designed such that it is made of a material with a high or large positive thermal expansion coefficient, yet is simultaneously mechanically stable. When the actuator 225 heats up, it simply becomes longer or expands significantly in the longitudinal direction. This will be explained in more detail below.

[0041] A pot T with a pot base TB is placed on top of the cooking surface 212, which protrudes significantly beyond the heating element 220 to the right, or rather, projects beyond it in projection. Such an overhang can be, for example, 3 cm to 6 cm and would enable heating operation, similar to that shown in the Fig. 1 and Fig. 2, significantly disrupt and render it inefficient. If the heating element 220 nevertheless begins to heat the pot T, the temperature rises primarily in the pot base TB first. Due to cross-heat conduction, the entire pot base TB becomes warm or hot. The overhanging area on the right may become 10°C to 20°C less hot than the area directly above the heating element 220, but it usually reaches temperatures of 150°C to 250°C or more relatively quickly. At these temperatures, the pot base TB develops considerable radiant heat S, which it radiates downwards according to the arrows towards the actuator 225, at least towards that area of ​​the actuator 225 that runs freely or protrudes below the heating element 220, i.e. at the outer end 227. The actuator 225 will then expand and lengthen. It can heat up over its entire length or completely by means of heat conduction and thus experience expansion along its entire length.Using the pulling element 232, it will pull the heating element 220 to the right. After a certain time, for example, 1 minute or 2 minutes, the actuator 225 is extended as far as shown in the dashed line, almost reaching the stop limit 216. Using the pulling element 232, it then moves or pulls the heating element 220 into the deflection position shown in the dot-dash line. Here, it can be seen that only a small portion of the radiant heat S from the pot base TB radiates onto the actuator 225, possibly heating it further.

[0042] This configuration makes it possible to move the heating element with a relatively simple thermal actuator with a positive thermal expansion coefficient. The actuator 225 can have a heat radiation area and a movement area. The heat radiation area is the area to the right of the heating element 220, into which the radiant heat S radiates. The movement area is formed here by the entire actuator 225, since it expands and is intended to expand as a whole.

[0043] In the Fig. 9 is shown in a modification, as in a hob 311 with hob plate 312 similar to the Fig. 8, a heating device 313 including heating element 320 and edge 321 can be provided by means of a differently designed thermally activated actuator. An actuator sleeve 335 is attached to the inside of a holding limit 316 of a carrier 315 including carrier surface 318, which actuator sleeve is preferably made of a material with good thermal conductivity, for example, metal such as copper or the like. A helical spring 325 made of a shape memory alloy is arranged in the actuator sleeve 335 as a thermally activated actuator. In the cool state, it is compressed, either automatically due to its design, or because it is actuated by opposing thermally activated actuators according to the Fig. 1 was compressed when they expanded. Alternatively, it can be made of a material that expands significantly when heated or, as a coil spring, elongates significantly.

[0044] The coil spring 325 is connected at its right end to a tension element 332, which can be designed as Fig. 8. Its left end is pressed against the bottom of the actuator sleeve 335. The tension element 332 extends through a hole in the bottom of the actuator sleeve 335 and is connected to the edge 321 of the heating element 320. The pot T and the pot base TB are now heated by the heating element despite the overhang on the right.

[0045] The Fig. Figure 10 shows how the radiant heat S from the pot base TB has heated the actuator sleeve 335 and thus also the coil spring 325 within it. The coil spring 325 has expanded considerably and thus lengthened until its outer end strikes the sleeve 335. It thus pulls the tension element 332 to the right and thus also the heating element 320. The length of the entire actuator, including the sleeve 335 and tension element 332, has thus shortened, even though the actual material or the actual actuator, namely the coil spring 325, has expanded or lengthened. This construction is therefore also a type of gear mechanism, as mentioned at the beginning.

[0046] From the Fig. 10 it can be seen that the heating element 320 has not moved completely centrally under the pot T. This can be due, for example, to the offset of the Fig. 3. However, the structural design does not allow for a greater movement. The sleeve 335 could still protrude to the right through the holding limit 316, and thus the coil spring 325 could extend even further as an actuator. However, this area would then no longer be as well exposed to the radiant heat S, and the movement of the heating element 320 would no longer be as easy. In any case, the pot T is in Fig. 10 but significantly better and more centrally positioned over the heating element 320 than in Fig. 9 with better coverage.

[0047] Yet another embodiment, which is not part of the invention, is shown in the Fig. 11 and Fig. 12. A heating device 413 has a round support 415 with a support surface 418, which has an outer circumferential holding limit 416. A round heating element 420, the diameter of which is approximately 10% to 15% smaller, is mounted on the support 415 or its support surface 418. In the annular space formed between them, which is sealed or closed to the side by the holding limit 416 and to the top by the support 415 and a sealed contact with the underside of a cooktop plate, wherein the annular space has an approximately constant width, hydrogel spheres 425 are arranged as thermally activated actuators. They rest on a support surface 418. Here, they have a diameter corresponding to the distance between the holding limit 416 and the heating element 420 or its edge 421, i.e., they rest radially on the inside against the heating element 420 and radially on the outside against the holding limit 416.Neighboring hydrogel spheres 425 are spaced closely apart, for example, between 2 mm and 2 cm, but this can also be different, so they can also be adjacent to each other. The heating element is in its basic position on the carrier 415; all hydrogel spheres are the same size and evenly distributed in a kind of row, specifically in a closed circular shape.

[0048] Above the heating element 420, a pot T with a pot base TB is placed on a hob plate (not shown) of a hob with the heating device 413. It is shown shifted to the right, thus having a protrusion on the right. In this protrusion, the pot base TB radiates radiant heat S into or onto the hydrogel spheres 425 in the right-hand area after the pot T has been heated by the heating element 420, with varying intensity depending on the degree of coverage. This varies as the Fig. 11 clearly shows, and it also decreases. Due to the heating of the hydrogel spheres 425, the water stored in them evaporates; alternatively, another suitable liquid is used. The hydrogel spheres then shrink by the volume of the evaporated water. The evaporated water, in turn, condenses most where it is coolest, namely in the opposite area, where it is absorbed by the hydrogel spheres 425 arranged there. These then expand by the volume of the absorbed water and thus become larger.

[0049] The Fig.Figure 12 shows how the heating element 420 has subsequently been moved to the right by the hydrogel spheres 425. These spheres are still positioned between the edge 421 of the pot T and the retaining stop 416, and in particular, still against both. The heating element 420 has moved so far to the right that it is located almost centrally beneath the pot T with its pot base TB. Thus, there is no longer any particular overhang that would need to be compensated for and that could influence the distributed hydrogel spheres 425, acting as thermally activatable actuators, to move the heating element 420 to one side. The heating element 420 can therefore remain permanently in this deflected position, not only during operation to heat the pot T, but also after cooling. A differently positioned and heated pot T could, in turn, have a different overhang, which in turn causes the heating element to move to a different position.

Claims

[1] Hob (211) with a hob plate (212) as a cover and with at least one heating device (213) underneath, the heating device (213) comprising: - a carrier (215), - at least one heating element (220), wherein the heating element o is arranged under the hob plate (212) and above the support (215), o has an edge boundary (221), o is movable on the support (215), wherein: - at least two thermally activatable actuators (225) per heating element (220) are provided on and / or within the heating device (213) for the heating element (220) in order to move it within the heating device above the carrier (215), - the thermally activatable actuators (225) are designed such that they project at least partially beyond the heating element (220) in a direction parallel to the plane of movement of the latter, - the thermally activatable actuators (225) are designed and attached to the heating element (220) in such a way that a thermally activatable actuator (225) supplied with radiant heat (S) from above moves the heating element (220) in such a way that the radiant heat (S) in the thermally activatable actuator (225) is reduced, characterized by that the thermally activatable actuators (225) are arranged in a plane below the heating element (220), wherein they are arranged partly below and partly outside the edge boundary (221) of the heating element. [2] Hob according to claim 1, characterized by that the thermally activated actuators (225) are arranged evenly distributed with the same distance. [3] Hob according to one of the preceding claims, characterized by that the thermally activatable actuators (225) are designed to move the heating element (220) by expansion. [4] Hob according to claim 3, characterized bythat a thermally activatable actuator (225) moves the heating element (220) by its expansion. [5] Hob according to one of the preceding claims, characterized by that the heating element (220) has a basic position, wherein the heating element is arranged centrally in the heating device (213) in the basic position and can be moved therefrom into various deflection positions. [6] Hob according to claim 5, characterized by that the heating element (220) remains in a deflected position after a movement there, as long as it is not moved by a thermally activated actuator (225) into another deflected position or into the home position. [7] Hob according to one of the preceding claims, characterized by that the thermally activatable actuators (225) comprise an element from the following group: expansion elements, bimetallic strips, bipolymer strips, shape memory alloy. [8] Hob according to one of the preceding claims, characterized by that each thermally activatable actuator (225) has a heat radiation area (227) and a movement area, wherein the heat radiation area (227) and the movement area interact in such a way that when radiant heat increases in the heat radiation area, the movement area causes the thermally activatable actuator (225) to move in such a way that the heating element (220) is moved. [9] Hob according to claim 8, characterized by that the thermally activated actuators have a negative thermal expansion coefficient and that the heat radiation area and the movement area are formed together. [10] Hob according to claim 8 or 9, characterized by that the radiant heat (S) is directed into the heat radiation area (227) and the movement area moves the heating element. [11] Hob according to one of claims 1 to 8, characterized bythat the thermally activatable actuators have as a movement area or in the movement area a material which expands when heated and has a positive expansion coefficient, wherein the movement area converts a movement towards a central area of ​​the heating element into a movement in the opposite direction via a gear, wherein the gear is fastened to the heating element, acts on the heating element and moves this in the opposite direction and in the process moves it at least partially over the heat radiation area.

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