WO2013010555A1

WO2013010555A1 - Cooking vessel for an induction hob

Info

Publication number: WO2013010555A1
Application number: PCT/EP2011/003573
Authority: WO
Inventors: Katarina Verhaegen; Hans SPRUYTTE; Kurt Coppens
Original assignee: Zwilling J.A. Henckels Ag
Priority date: 2011-07-18
Filing date: 2011-07-18
Publication date: 2013-01-24

Abstract

The invention relates to a cooking vessel for an induction hob, the cooking vessel containing a cooking pot (11) with a base, which is heated up by means of an alternating electromagnetic field and has an upright pot wall (13), which adjoins the base, the cooking vessel having a thermally insulating outer jacket (12), which at least partially surrounds the pot wall (13) and the base, and projects with at least one lower jacket area (B) and/or a supporting element downwards relative to the base of the cooking pot such that an air gap (L), open at the bottom, arises between the base and the lower edge of the jacket, in order to create clearance between the underside of the base and the top of the hob.

Description

Cookware for an induction hob

The invention relates to a cookware for an induction hob, wherein the

Cookware contains a saucepan with a bottom over a

alternating electromagnetic field is heated and has a raised pot wall, which connects to the ground.

From US Pat. No. 3,209,746 a cookware is known which consists of a casing which is mounted around a pot so that the heat is captured in this way and the side walls of the pot can become very warm in order to better transfer energy to the food create.

In US 3,777,094 a cookware is known which consists of a material which is magnetically inducible and coated on the outside with a material which transmits magnetic induction. Here, a thermally insulating material must be placed under the bottom of the pot, which is resistant to high temperatures. In terms of production technology, this can only be achieved with great difficulty and cost-intensive.

From US 3,745,290 a cookware is known, which is provided with a saucepan, which is suspended in a supporting container. This keeps the food warm longer and keeps the wall cool. The bottom of the carrying container always remains in direct contact with the induction hotplate.

CONFIRMATION COPY From US 5,643,485 a cookware is known which consists of a double wall with a vacuum therebetween, which is to prevent the heat transfer.

The object of the invention is to provide a cookware, which is suitable for inductive heating and in which both the wall temperature and the energy consumption during and after the cooking process in comparison to

conventional cooking pots remain low.

This object is achieved in that the cookware has a thermally insulating outer jacket, which surrounds the pot wall and the bottom at least partially, and projects with at least one lower shell region and / or a support member relative to the bottom of the saucepan down so that a downwardly open air gap between the bottom and the bottom of the shell is to provide a space between the bottom of the bottom and the top of the hob.

The inventive aspect lies in the fact that the inventive

Cookware when cooking food over the induction source (especially induction hotplate) in a kind of coat, wrapping, skeleton or "shell" without ground hangs around the side walls of the saucepan partially or wholly.The distance between the suspended saucepan and The induction hot plate is chosen so that there is no measurable loss and the magnetic field lines are maximally absorbed in the bottom of the cooking pot.

The mantle can either be made to measure for a specific cooking pot or designed to be customizable, making it suitable for use on a variety of existing cooking pots.

The saucepan itself or at least its bottom (or a component of the

Bodens) is made of a material that can be warmed up by magnetic induction. The aforementioned coat is made of a material which is not directly accessible via magnetic induction (or, in other words, for magnetic induction transparent) is warmed up. For example, an air gap is provided between the jacket and the cooking pot which forms a thermal barrier in this way. This set-up is designed to limit losses due to convection around the saucepan as much as possible, so that the food to be prepared is thermally better insulated to the outside. As a result, the heat remains longer in the saucepan, or in other words, it must be transported less energy to bring the food to be prepared in the saucepan to a certain temperature or to hold. After cooking, or in other words, after switching off or removing the induction source, the food in the cooking pot stays warm longer than in already known cookware.

The thermal insulation provided by the aforementioned jacket ensures that the inner wall of the cooking pot is thermally isolated from the outer wall of the jacket when the pan is in the jacket. There is no risk of burns if the jacket is touched during cooking and thereafter. Furthermore, when using the

Cookware according to the invention the positive effect that the bottom of the hot pot, the work and / or table top (when serving food) does not touch directly when it is parked with the coat on it. As a result, the cooking instrument in its entirety can be freely moved and set down without having to use a backing or other protective material.

The coat can be made of different materials or material mixes. - One requirement is that the material is not warmed up by the magnetic flux of the alternating magnetic field generated under the cooking plate. Because the shell only comes in contact with the cooking pot at some limited locations (handle or rim, recesses or grooves), and if an air gap is provided between the cooking pot and the jacket, a material or a combination of different materials can be selected without that too strict conditions in connection with the

Resistance to high temperatures are provided. This "constructive freedom" can be used to create an appealing design for the

To choose cookware casing. Furthermore, by the relatively simple Requirement profile to the cookware jacket a low-cost production of this can be achieved.

Furthermore, a further, particularly advantageous embodiment of the idea according to the invention is possible. Here, the jacket described is directly part of the

Cookware. The walls of the cookware and the jacket are made of the same non-magnetic material as e.g. 18/8 or 18/10 stainless steel, other austenitic steels and other alternative materials such as aluminum or copper. The said pot with coat can easily in one

Deep drawing process are produced. Alternatively, pot and shell are fabricated separately and then the jacket is welded to the upper edge of the pot. (The jacket and the cookware can have different thicknesses). Since the inner side wall of the shell thereby has a larger diameter than the outer diameter of the cookware arises in this embodiment, the desired air gap. The execution of the walls can be parallel and cylindrical, a configuration with a non-parallel, conical design is also possible. Furthermore, it is particularly advantageous in the last-mentioned embodiment to design the lower edge of the side walls of the shell longer than the walls of the cooking pot with bottom. Thus, an air gap is created under the bottom of the cooking pot as the shell and cookware are carried by the bottom edge of the shell. The lower edge of the shell (which rests on the plate of the hob can be sanded or folded (or the like) be to effectively prevent damage to the hob by moving the cooking appliance.

The aforementioned embodiment can be done by deep drawing.

In summary, this invention provides i.a. these advantages:

- Achieving energy savings during the cooking process as well

Achieving a longer cooking time / warming time of the food without supplying additional energy thanks to a good thermal insulation; - safety in use thanks to a lower external wall / jacket wall temperature;

- The proposed new cookware can be placed directly - when hot - on a shelf or on the dining table (for serving), as there is no direct contact between the bottom of the saucepan and a surface underneath ('hanging' table);

- possibility of realization of an appealing design thanks to

Usability of different materials and the fact that these do not need to be resistant to an extremely high temperature.

It was thus created a cookware in which the risk of burns is minimized by the Berühung the wall and its energy consumption is greatly reduced compared to the existing cooking pots for induction and other types of stoves.

Advantageous embodiments of the invention are listed in the subclaims.

Embodiments are illustrated in the drawings and will be described in more detail below. Show it:

Figure 1 shows an axial vertical section through a first

embodiment

Figure 2 is an axial vertical section through a second

embodiment

FIG. 3 shows an isometric view of the embodiment according to FIG. 2

Figure 4 is a perspective view of a third

Embodiment, Figure 5 is a perspective view of a fourth

Embodiment,

Measured the temperature at the outer wall, the same curve as in Figure 6 to the

Measured by hand,

Temperature course under the cookware,

Warming up a quantity of water as

Function of the distance between the cooking fire

And the hung cooking pot,

Heating and cooling rate of a quantity of water In a cover pot (without shell) and suspended

Pot, the effect of the color of the inside of the shell: ever

Darker the color, the better the insulating effect.

In induction hotplates, induction eddy currents or Foucault currents are generated by means of a changing electromagnetic field below the cooking plate. These eddy currents are generated in a part of a cooking pot which is magnetizable, mainly in the bottom of the cooking pot. In this way, the cooking pot is heated and not the hotplate. The heat source does not need to be as large in diameter as the bottom of the saucepan, which contributes to the safety of the system and the minimum consumption of energy.

In an average family, the proportion of energy used to heat the food is about 15 to 25 percent of the total

Energy consumption of the said average household. This percentage will be even higher in the future, since today's creation is intense of energy-efficient homes and houses and in particular energy-efficient heating systems and lighting systems dedicated. The relative interest in the consumption of energy in cooking is thus further increased. This invention seeks to significantly reduce the cost of energy for cooking.

It should also be noted that due to the risk of burn hot

Cookware relatively many household accidents happen. Most children are endangered here, but also elderly people and other physically restricted groups of people. In view of the demographic development (aging) of populations in the industrialized nations, there is a great need for safe cooking facilities. A reduction of the risk of injury is thereby

in particular ensured by achieving a low temperature on the walls of the cookware. These requirements fulfilled the cookware according to the invention in full.

The above-mentioned aspects of energy saving cooking as well as the low temperature of the wall are further explained in the following paragraphs.

The cookware according to the invention is generally a jacket 12 for a saucepan and a saucepan provided with such a jacket. This sheath 12 according to the invention is made of a thermally insulating material which is highly transparent to a magnetic field, i. h. that it can not be heated by the magnetic field 15, which is generated below the cooking plate 16 and extends at least into the bottom of the cooking pot when it is placed on the surface of the cooking plate. The mantle usually extends over the wall area of the

Saucepan, while the bottom portion of the saucepan remains uncovered / free. When draining the cooking pot in the mantle, this extends over at least one support element B away to the bottom of the saucepan over. If the saucepan is placed together with the shell in this way on a flat surface, a free space, in detail an air gap L, between the bottom of the saucepan and this surface is present. The above-mentioned support member B can take various forms. This support element may be formed, for example, by two, three or more inconspicuous supports or feet or consist of a circumferential ring. The support member preferably forms a whole with the jacket and is

preferably made of the same material as the jacket.

The cooking pot rests on or in the mantle, in such a way that no direct contact between the bottom of the saucepan and a flat surface is possible, on which the cooking pot is placed with the mantle. For example, if the saucepan shows a conical shape, then the inner wall of the shell can also be made conical in such a way that the saucepan can be placed almost snugly in the shell. In this case, the smallest outer diameter of the cooking pot is preferably smaller than the largest inner diameter of the shell, so that this jacket extends at least with the above-mentioned support element to the bottom of the cooking pot over.

In another embodiment of the jacket according to the invention, the cooking pot with the handles 17 resting on it rests in the space provided for this purpose

Recesses in the upper edge of the shell, wherein it is ensured that the bottom of the cooking pot does not extend to the above-mentioned support element, in such a way that between the lower edge of the shell and the bottom of the cooking pot is a small distance.

Optionally, the cooking pot may have one or more ribs or protuberances with which the cooking pot rests on the mantle, with the inner wall of the mantle at least partially surrounding the outer wall of the cooking pot.

In one embodiment, at least one spacer is provided which extends between the inner wall of the above-mentioned shell 12 and the upstanding wall 13 of the cooking pot so as to form an air gap between them, with which the thermal insulation is to be improved. Such a

Spacer is formed for example by one or more ribs, which is provided on the inner wall of the shell or on the upstanding wall of the cooking pot or are. Figure 1 shows an embodiment with a jacket 12 which is integrally formed at its upper end to the upper end of the pot wall 13.

Figure 2 shows the principle of the invention. The actual cooking pot 1 rests on the shell 12 and is' suspended 'in this way in the jacket on the induction hob 16'. The lines 5 are the induction lines of the

magnetic field; the slightly hatched wall 13 is that part of the

Cookware, which is heated by magnetic induction, the dark hatched part 14 is that part of the cookware (mantle), the (as already in a

previous paragraph) is made of a material that is transparent to magnetic induction.

In Figure 2, the handle 17 is part of the cooking pot. In Figure 3, however, the handle is part of the jacket. It shows how the cooking pot and the coat fit together. The handles are integrated into the coat. These handles can be realized both as supportive of the handles of the actual cooking pot or as a handle per se.

The jacket 12 may be provided with cuts for the handles of a cooking pot. The saucepan is suspended in the mantle with the two handles resting on the mantle recesses. It is obvious that this model can in principle be made to measure for existing cooking pots. By creating openings or grooves, or a combination of the two, at the correct height in the shell, or by incorporating a consumer controllable mechanism, the cooking pot can be hung in the shell at a well-defined distance from the cooking fire.

The aforementioned shell shells can be created in numerous forms. It is possible to design stackable jackets as shown in FIG. However, it is also possible to develop a foldable or collapsible system using, for example, narrow slats of plastic and / or natural materials such as wood or other magnetic materials which are transparent to induction. An example is Figure 10, which shows a prototype of narrow wooden slats made of a stretchy or non-stretchable band held together. This version has the additional advantage that this jacket takes up little space when stowed. In general, it can be argued that various concepts are possible: a stackable concept or a design concept that strives for a particularly aesthetic shape that gives the cooking pot a pleasing look.

For verification, probes were mounted on the jacket and in the saucepan itself. The data log was made every 5 seconds via a MicroLog (tl500, PT100). At the beginning of each measurement cycle, a 1-minute wait is made to equilibrate the thermoprobes. Then pour 1 liter of tap water into the cookware and wait another 1 minute. Subsequently, the induction hot plate is turned on, with a power of 2000 watts for 15 minutes. Figure 6 shows the temperature of the wall of the cooking pot as a function of time. Curve 51 shows the evolution of the temperature of the wall of a reference saucepan. The peak value is 92 ° C. Curve 52 shows the evolution of the temperature of the jacket wall of the cooking instrument described in this invention. It barely reaches 42 ° C, ie a temperature below the pain threshold of 45 ° C. The graph of Figure 7 shows the same curves, but now measured by handles. Both curves are below the temperature at which skin damage occurs.

The temperature below the cooking instrument (cookware bottom) was measured in Figure 8 after the saucepan was lifted off the induction plate (but still hanging in the mantle). The maximum temperature measured was 45 ° C, which is clearly lower than the maximum temperatures that most commercially available countertops are resistant to. For comparison: a common bottom of a saucepan effortlessly reaches 200 ° C.

Figure 9 describes the rate of warming up the contents of the cooking pot as a function of height above the induction hotplate. For this purpose, a thermoprobe is placed in the water in the saucepan. The speed of

Warming is called the directional coefficient in the graph

expressed. It is clear that the cooking instrument has to be designed in such a way that the cooking pot 'hangs' less than 4 mm above the cooking fire. From here on is the Directional coefficient apparently the same as when the bottom of the saucepan of the bare pot rests directly on the cooking fire, ie 20.5 + - 0.5 ° C / minute. This distance depends very well on the type of induction source used.

Figure 10 describes the rate of warming and cooling of the contents of the cooking pot, both naked and surrounded by the mantle. As can be deduced, the heating takes place at least as fast as the naked saucepan (the slight improvement is due to the better thermal insulation: 21, 81 ° C for the cooking pot in the mantle against 20.81 ° C for the naked saucepan), but the speed of cooling is much lower. In this specific case, even by 30 percent (-1, 37 ° C / minute versus -1, 95 ° C / minute).

Figure 11 shows the effect of the color of the inner wall of the jacket. The graph shows that the contents of the cooking pot cool much less quickly if the inner wall of the shell is colored black than if the wall were white. The handles remain about the same warm. The mantle of the black pot becomes a few degrees warmer, which is understandable, since it better holds the heat.

The jacket can also be made of a mix of materials without imposing too high requirements for resistance to high temperatures. There are embodiments to produce, which are produced for example of wood, made of felt, leather or cardboard.

The cookware does not necessarily have to be cylindrical, it may also have a rectangular or square cross-section and also be conical or have prismatic shape. Also, the inner wall of the shell does not necessarily have to be cylindrical, but it may also have a conical or prismatic shape.

Claims

claims

Cookware for an induction hob (16), the cookware containing a cooking pot (11) with a bottom (10) which is heated by an electromagnetic alternating field (15) and a raised pot wall (13), which is at the bottom ( 10), characterized in that the cookware has a thermally insulating outer jacket (12, 14) which at least partially encloses the pot wall (13) and the bottom (10), and at least one lower jacket region (B) and / or one Support member relative to the bottom of the cooking pot (11) downwardly projecting such that a downwardly open air gap (L) between the bottom (10) and the lower edge of the jacket (12, 14), by a distance between the bottom of the bottom (10) and to create the top of the hob.

2. Cookware according to claim 1, characterized in that the jacket (12, 14) consists of a non-ferromagnetic material.

3. Cookware according to claim 1 or 2, characterized in that the jacket (12, 14) connects to the pot wall (13).

4. Cookware according to one of the preceding claims, characterized

in that at least over part of the surface of the pot wall (3) there is an annular air gap between the casing (12, 14) and the cooking pot.

5. Cookware according to claim 4, characterized in that at least one spacer is provided which extends between the

Inner wall of the shell (12, 14) and the outside of the pot wall (13) extends to form in this way the annular air gap.

6. Cookware according to one of the preceding claims, characterized

in that the support element (B) is formed by one or more supports which form a unit with the casing (12, 14) and likewise consist of a non-ferromagnetic material.

7. Cookware according to one of the preceding claims, characterized

characterized in that the cooking pot (11) rests with one or more of its handles (17) in recesses (42) provided for this purpose in the upper edge of the casing (12, 14).

8. Cookware according to one of the preceding claims, characterized

characterized in that the cooking pot (11) on the outside has one or more ribs or protuberances with which it rests on the casing (12, 14), the inner wall of the casing (12, 14) being the outer one

Pot wall (13) at least partially surrounds.

9. Cookware in particular according to one of the preceding claims,

marked

- By one of a heatable by magnetic induction

Material prepared cooking pot (11) or at least the bottom thereof;

by a jacket (12, 14) made of a non-ferromagnetic material, in which the cooking pot (11) can be suspended at a distance via an induction hob (16),

- Wherein the saucepan () and the jacket (12, 14) separated by an air gap and the bottom (10) of the cooking pot (11) and the

Induction hob (16) are separated by an air gap (L).

10. Cookware according to one of the preceding claims, characterized

in that the cooking pot (11) consists of stainless steel, iron, cast iron, titanium and in particular on the outside and / or inside with enamel, ceramic, a paint or powder layer or a

Non-stick layer, preferably PTFE coated.

11.Kochgeschirr according to one of the preceding claims, wherein the jacket (12, 14) made of plastic such as polycarbonate, polypropylene, polyvinyl carbonate, silicone or ceramic material or wood, cork, glass, leather, textile, felt or non-magnetic material such as 18/8 or 18/10 steel or austenitic steel or aluminum or copper.

12. Cookware according to one of the preceding claims, characterized

characterized in that one or more handles (7) on the jacket (12, 14) is attached / are.

13. Cookware according to one of the preceding claims, characterized

characterized in that one or more handles (17) is attached to the cooking pot (11) is / are.

14. Cookware according to one of the preceding claims, characterized by a double-walled lid.

15. Cookware according to one of the preceding claims, wherein the cooking pot (1) in particular with its upper edge from the upper edge of the jacket (12, 14) is worn.

16. Cookware according to one of the preceding claims, characterized

characterized in that the upper edge of the pot wall (13) with the upper edge of the jacket (12, 14) is connected in particular cohesively.

17. Cookware according to one of the preceding claims, characterized

in that the cooking pot (11) is supported by recesses (42), grooves or indentations in the edge or in the side wall of the jacket (12, 14).

18. Cookware according to one of the preceding claims, characterized

in that the air gap (L) has a height of 0.5 to 6 mm.

19. Cookware according to one of the preceding claims, characterized

in that there is at least one downwardly projecting projection on the underside of the bottom (10) which bridges the air gap (L).

20. shell (12, 14) for a cooking pot (11) for an induction hob (16), wherein the cooking pot (11) by a electromagnetic alternating field (15) heatable bottom (10) and a subsequent to the ground

upstanding pot wall (3), wherein the shell (2, 14) has a conical or cylindrical inner surface into which a cooking pot (11) is to be accommodated almost suitably, the shell (12, 14) the floor (10) completely or substantially free and extends with at least one lower shell region (B) and / or a support element downwardly past the bottom of the cooking pot (1) so as to open a downwardly open air gap (L) between the bottom (0 ) and the lower edge of the shell (12, 14).

21. A jacket according to claim 20, characterized in that the air gap extends over the full diameter of the lower part of the jacket (12).

22. A jacket according to any one of claims 20 to 21, d a d u r c h

characterized in that this annular, cylindrical or

Frusto-conical.

23. A jacket according to any one of claims 20 to 22, d a d u r c h

characterized in that it is made of plastic such as polycarbonate,

Polypropylene, polyvinyl carbonate, silicones or of ceramic material, wood, cork, glass, leather, textile, felt or of a thermally insulating and non-ferromagnetic material.

24. A jacket according to any one of claims 20 to 23, d a d u r c h

characterized in that it comprises one or more handles (17).