FOOD PREPARATION DEVICE

Description

TECHNICAL AREA

[0001] The present invention relates to a device for preparing food, in particular a portable lunchbox for storing, transporting and preparing food, and a method for operating such a device. STATE OF THE ART

[0002] In today's business world, and also during training, it's becoming increasingly difficult to eat healthily throughout the day. Restaurants are often crowded and expensive, canteens rarely offer tasty food, and snack bars usually offer unhealthy fare. This creates a need to be able to easily prepare food brought from home. This need is further amplified when the employer doesn't provide a kitchen or, at best, a microwave.

[0003] Therefore, state-of-the-art technology includes lunchboxes that allow for the heating of food brought along on site.

[0004] WO 2015 / 177726 A1 describes a lunchbox comprising an upper and a lower shell, which are hinged and can be closed together. A tray with an integrated heating element is located in the lower shell, which can heat food placed in the tray. When the upper shell is closed, a seal is located between the upper shell and the tray.

[0005] CH 712870 A2 describes a container for transporting and heating food, comprising a main body and a lid that seals tightly onto it. Inside the container is a receiving tray with its own lid, which can be heated by heating elements located in the main body.

[0006] US 2016 / 0045054 A1 describes a cooking container with an outer body containing a heating cavity into which water and a heating element are placed. An inner body is positioned above the heating cavity within the outer body. The water in the heating cavity is heated, thereby warming the inner body and any food contained within it. The heating cavity and the interior of the inner body are not connected.

[0007] WO 03 / 101268 A1 discloses a thermally insulated container with a lid, wherein a heating plate is attached to the bottom of the container. The container is used for heating and / or keeping ready-made meals warm and for cooking raw food. US 2014 / 261381 A1 describes a heating container for warming or cooking food. The heating element is integrated into the heating container. A lid seals the container, making it suitable for outdoor use.

[0008] Most state-of-the-art appliances only allow for heating food. Steamers are also available, but they are relatively complex in design, correspondingly heavy and expensive. PRESENTATION OF THE INVENTION

[0009] It is an object of the present invention to create an improved device, in particular an improved lunchbox.

[0010] This problem is solved by a device having the features of claim 1 or claim 14 and by a method having the features of claim 11.

[0011] The inventive device for preparing food according to claim 1 has the following features: a food cavity for receiving food; a heating cavity for receiving water; a heating element for heating water in the heating cavity; at least one pressure sensor configured to detect pressure surrounding the device; a first temperature sensor configured to detect temperature inside the heating cavity; and a control device configured to control the heating power of the heating element based on data detected by the pressure sensor and the first temperature sensor.

[0012] In the inventive method for operating the above device according to claim 11, water in the heating cavity is heated by means of the heating element, the pressure surrounding the device is detected by means of the pressure sensor, the temperature inside the heating cavity is detected by means of the first temperature sensor, and the heating power of the heating element is controlled by means of the control device as a function of the data detected by the pressure sensor and the first temperature sensor.

[0013] The inventive device for preparing food according to claim 14 has the following features: a food cavity for holding food; a heating cavity with a water cavity for holding water; a heating element for heating water in the water cavity; a first temperature sensor configured to detect a temperature inside the heating cavity but outside the water cavity; a second temperature sensor configured to detect a temperature inside the water cavity; and a control device configured to control the heating power of the heating element depending on the data detected by the first and second temperature sensors.

[0014] The pressure sensor is, for example, arranged in a cavity separate from the food cavity and the heating cavity, which is in pressurized contact, e.g., gas contact, with the environment of the device. This cavity is preferably an electronics cavity as described below. The pressure sensor is, for example, arranged on a common circuit board with other electronic components. Alternatively, the pressure sensor is arranged on an outside of the device.

[0015] Since a pressure sensor designed to detect external pressure is generally not located within the food or heating cavity, it does not necessarily need to be specially designed to be moisture-resistant, thus saving costs. Furthermore, the pressure sensor is not contaminated by contact with the food.

[0016] Preferably, the temperature sensor is arranged in the heating cavity. In preferred embodiments, the temperature sensor is arranged in the water.

[0017] For example, the control device can be set up to switch off the heating element after a defined heating period, in order to prevent, for example, the battery from discharging too deeply.

[0018] In some embodiments of the invention, the control device is configured to regulate the heating power depending on the ambient pressure and the temperature in the heating cavity. This allows, for example, the heating temperature to be optimized in an energy-efficient manner. Particularly in embodiments that also enable cooking, it also prevents food from being prepared at excessively high or low temperatures.

[0019] This arrangement can be used without the switching device described below. The arrangement is not limited to lunchboxes; it can also be used for other types of food preparation devices. Furthermore, the device does not necessarily have to be suitable for storing or transporting food. For example, it could be a steamer built into a kitchen unit or a steamer for home use.

[0020] Thanks to the control of the heating output based on a combination of external pressure measurement and heating cavity temperature measurement, the device according to the invention has the advantage that both failure-prone valves and expensive liquid-resistant pressure sensors in the heating cavity can be dispensed with. This increases the reliability of the device and simultaneously reduces manufacturing costs.

[0021] The device according to the invention is particularly suitable for lunchboxes. It provides a device that does not require a pressure relief valve. Such valves can become contaminated by food and are therefore unhygienic. Furthermore, contamination poses the risk that they will not open when needed, or not open sufficiently. If they do open, however, the energy loss due to the escaping steam is relatively high, so heating takes longer and consumes more energy than necessary. These disadvantages are eliminated by the use of at least one pressure sensor.

[0022] In preferred embodiments, the device is designed to maintain the temperature in the heating cavity within a range determined by taking into account the ambient pressure during the heating process.

[0023] In preferred embodiments with the pressure sensor set up to determine the ambient pressure, the temperature sensor set up to determine the temperature in the heating cavity, and the control device, the device is set up such that At the beginning or during a heating process, the ambient pressure is measured via the pressure sensor; a minimum temperature is determined from the measured ambient pressure, e.g. via an internal database, e.g. a minimum temperature at which water evaporates, and the heating element is operated in such a way that during the heating process the temperature measured in the heating cavity by the temperature sensor is above the minimum temperature.

[0024] The device is preferably configured to set a minimum temperature of 100°C when the ambient pressure is 1033 bar, e.g. because the steam temperature of water at this pressure is 100°C.

[0025] In preferred embodiments with the pressure sensor set up to determine the ambient pressure, the temperature sensor set up to determine the temperature in the heating cavity, and the control device, the device is set up such that At the beginning or during a heating process, the ambient pressure is measured via the pressure sensor; a maximum temperature within the heating cavity is determined from the measured ambient pressure, e.g., via an internal database; and the heating element is operated in such a way that the temperature measured in the heating cavity by the temperature sensor during the heating process is below the maximum temperature, e.g., by switching off the heating element if a temperature exceeding the maximum temperature is measured in the heating cavity by the temperature sensor during the heating process.

[0026] The device is set up, for example, so that when the ambient pressure is 1,033 bar, it sets a maximum temperature of 106°C, e.g. because the steam temperature of water at a pressure 0.3 bar higher is 106°C and therefore, when the temperature is below 106°C, the pressure difference between the heating cavity and the environment is a maximum of 0.3 bar.

[0027] In preferred embodiments, the device features a redundant sensor system for controlling the heating power to further enhance safety. Preferably, the device has two sets of sensors, each comprising, for example, an external pressure sensor and a heating cavity temperature sensor. The control device is preferably configured to interrupt the heating process if at least one part of the sensor system detects values ​​outside the safe range. The redundant sensor system thus reduces the susceptibility to errors.

[0028] The device according to the invention preferably comprises a signal output unit. The signal output unit is configured to output an acoustic and / or optical signal. An optical signal output unit can be designed as a lighting unit, e.g., comprising one or more LEDs, and can be configured to illuminate in one, two, or more colors.

[0029] In preferred embodiments, the signal output unit indicates, for example, whether the heating element is activated, progress (especially completion) of a heating or steaming process, charge level of the accumulator, temperature in the heating cavity and / or food cavity, error messages, and / or fill level in the heating cavity.

[0030] In preferred embodiments, the device has a user interface through which the user can start a heating process. The user interface includes, for example, a switch. The user interface is preferably configured to allow the user to cancel a heating process.

[0031] Preferably, the lunchbox according to the invention allows for a choice of food preparation.

[0032] In a preferred embodiment, the portable lunchbox for storing, transporting, and preparing food has a switching device that can be switched from a first state to a second state. The lunchbox is designed to heat food arranged in the food cavity in the first state of the switching device, and to steam food arranged in the food cavity in the second state of the switching device.

[0033] In preferred embodiments, the first state of the switching device also serves to sufficiently seal the lunchbox and, in particular, the food container for transport.

[0034] In this text, the term "preparation" generally refers to the heating of a finished dish. A dish can be heated by applying heat, either through heat transfer or by adding steam, such as steam. In a broader sense, "preparation" here also refers to cooking, or simmering, food, for example, boiling potatoes or vegetables until tender. Some embodiments of the invention only allow for heating the food, while others additionally allow for cooking or simmering.

[0035] Steaming, also known as steaming, is an increasingly popular cooking method, not only because of its health benefits. A steamer can be used to reheat food or, with a longer heat source, to cook it. This method is commonly called steam cooking. The main advantage of heating with a steamer is that the food doesn't dry out.

[0036] Thanks to this lunchbox, the user can choose the preparation method depending on its contents. If they are carrying a pre-prepared meal one day, they can simply heat it up. If they are carrying food that still needs to be cooked on another day, they can do so using the same lunchbox. Furthermore, they can preheat the same food first and then steam it, or vice versa. To do this, they simply need to activate the switch. Commercially available containers with prepared food can also be used in the lunchbox according to the invention.

[0037] The user can therefore use the same lunchbox to transport, store, and prepare their food. Preferably, a seal is provided that seals against leakage in each of these situations, preventing liquids and odors from escaping. This is particularly advantageous when the lunchbox is stored and used directly at the workplace, for example, in an open-plan office.

[0038] Preferably, heating and, if necessary, cooking is carried out using water, which is poured into a suitable cavity. This can be done before transport or immediately before preparing the food.

[0039] In preferred embodiments, the lunchbox has a fluid connection between the heating cavity and the food cavity, which is configured to be opened and closed by the switching device. Hereinafter, the fluid connection is referred to as the gas connection. It comprises connections that allow at least vapor to pass through.

[0040] The lunchbox is preferably designed such that, in the first state, the switching device closes the gas connection, preventing, in particular, water vapor from passing from the heating cavity into the food cavity. Therefore, when water in the heating cavity is heated, only heat can be transferred to the food cavity, so that food placed in the food cavity is only warmed. In preferred embodiments, this state also corresponds to the state in which the lunchbox can be transported and stored with the food, even if the water for heating the food has already been poured into the lunchbox; i.e., the lunchbox is ready for use. Preferably, a tight seal is present in this state, preventing the contents and odors from escaping.

[0041] The lunchbox is preferably designed such that the switching device, in the second state, opens the gas connection, allowing water vapor, in particular, to pass from the heating cavity into the food cavity. Thus, when water in the heating cavity is heated and water vapor is produced, this vapor can enter the food cavity, steaming the food inside.

[0042] The heating element is preferably arranged in the heating cavity. In preferred embodiments, the bottom of the heating cavity is designed such that, at least in one intended use position of the lunchbox, any water in the heating cavity always flows towards the heating element. The heating cavity preferably has a sloping bottom. If the heating element is arranged centrally in the bottom of the heating cavity, the most uniform heating of the food is achieved. Preferably, it is plate-shaped towards the heating cavity.

[0043] In preferred embodiments, the heating element is electrically operated, and the lunchbox includes a battery that supplies power to the heating element. Preferably, a power connection is provided through which the battery can be charged. This power connection is preferably compatible with common chargers (e.g., USB-C, Lightning). In other embodiments, mains power is provided as an alternative or additional option. This mains power supply is particularly advantageous if the lunchbox is intended not only for heating food but also for cooking it.

[0044] Preferably, the lunchbox has a lid that can be completely removed from a base, here referred to as the bottom. This allows access to the food compartment. Preferably, water also enters the heating compartment through the same opening. In other embodiments, a separate opening is provided for this purpose.

[0045] To prevent odors from escaping and to ensure the lunchbox is portable, at least one seal is preferably provided. Additionally, a mechanism is included that connects or seals the food compartment to the heating compartment to enable or prevent steaming. This mechanism preferably also has a seal. These two seals enhance safety during transport and storage of the filled and ready-to-use lunchbox.

[0046] In preferred embodiments, the lunchbox therefore has a first seal, wherein in the first state of the switching device the first seal seals the food cavity gas-tight against the heating cavity, and in the second state of the switching device the switching device removes the first seal, at least partially, so that the food cavity and the heating cavity are gas-connected.

[0047] In preferred embodiments, the lunchbox has a second seal which, when the lunchbox is closed, seals the food cavity gas-tight to the outside. This same seal is preferably designed to seal the heating cavity, and preferably also the food cavity, gas-tight and thus also liquid-tight to the outside in both the first and second states of the switching device.

[0048] Preferably, when the lunchbox is closed, both seals seal the food compartment from the outside of the lunchbox. This provides at least double protection against leakage during transport.

[0049] Depending on the embodiment, the first seal and the second seal are two separate seals. They are preferably circumferential. They are preferably made of silicone.

[0050] In a preferred embodiment, these two seals are formed as a single piece. Preferably, they form a self-contained part with a closed circumference and a through-opening in the center. This sealing part can, for example, be easily manufactured from silicone. The first seal preferably forms an inner part of the sealing part, and the second seal an outer part.

[0051] In preferred embodiments, apart from the electronics and the operating and display elements, the lunchbox essentially consists of the lid, the base, and the container arranged between them. Preferably, the outer circumference is defined by the lid and the base.

[0052] The heating element is preferably electrically operated. In preferred embodiments, an electronics cavity is provided in the base, in which electronic components of the lunchbox, for example, the heating element, are arranged. Further components in the electronics cavity include, for example, a battery, a circuit board, cables, at least one push button, an acoustic signal output unit, at least one pressure sensor, at least one temperature sensor, at least one control unit, and, in the case of mains operation, at least one transformer. A power connection and / or optical signal output units (e.g., LEDs) are preferably arranged in a wall of the electronics cavity. For this purpose, the base is preferably designed in two or more parts.

[0053] In preferred embodiments, the lid is attached to the base by means of at least one fastening element. Preferably, several fastening elements are provided. They can be of different designs. Preferably, they are snap-in elements that can be clicked into the base and / or the lid. The snap-in elements are preferably designed as tabs, which are preferably arranged on the lid. For example, they are pivotably arranged.

[0054] The switching elements can be designed in different ways. They can be formed by the cover itself, by sliding elements for the cover, or by other means.

[0055] In a preferred embodiment, at least some of these fastening elements are designed as switching elements of the aforementioned switching device. The fastening elements, or at least some of them, can thus fulfill a dual function: on the one hand, they enable the opening and tight sealing of the lunchbox; on the other hand, they allow switching from a warming position to a steaming position. This is a simple design that allows for easy operation and cost-effective manufacturing.

[0056] For example, some of the fastening elements can be moved into an open position, while others remain in the closed position. The open elements allow gas to pass between the heating cavity and the food cavity, while the closed elements ensure that the lunchbox remains gas-tight.

[0057] In preferred embodiments, when the lunchbox is closed, the second seal is arranged between the lid and the base, for example clamped in place, and / or the container is arranged and clamped between the lid and the base.

[0058] In preferred embodiments comprising a control unit, a temperature sensor for detecting the temperature in the heating cavity, and a signal output unit, the control unit is configured to output a signal if a temperature increase is not detectable quickly enough after the heating element has been heated. Such a case can occur, for example, if there is no or too little water in the heating cavity, which the user can be alerted to by the signal.

[0059] Since not only the water but also the air inside the lunchbox heats up, this can lead to undesirably high internal pressure. In a preferred embodiment, the lunchbox therefore has a wall that moves outwards as the water heats up, allowing for an increase in volume within the interior of the lunchbox if the outer casing is sealed. For example, the lid of the lunchbox is flexible, enabling a change in volume as the interior heats up. The lid can, for instance, bulge inwards automatically or through manual pressure when closed and move outwards as the lunchbox heats up. In alternative embodiments, the entire lid can be moved upwards manually or automatically by means of the overpressure, thus increasing the volume during heating.

[0060] The outer seal is preferably designed to open or leak at a predefined internal pressure. If the outer seal is a sealing ring, it preferably becomes leaky at a specific internal pressure. This prevents excessive overpressure inside the lunchbox. In preferred embodiments, the lunchbox is sealed up to a pressure difference of 0.3 bar and leaks or opens at a pressure difference between the internal and external pressure of at least 0.31 bar and at the latest at 0.49 bar.

[0061] The control unit preferably allows monitoring of whether all or part of the air has escaped from the lunchbox. If the food and the heating chamber cool down again, a vacuum can form, making it difficult to open the lunchbox. In some embodiments, this can also be prevented by the control unit. If a leak is detected in the lunchbox due to overpressure or underpressure, some embodiments automatically equalize the pressure. All these variants include a first temperature sensor that measures the temperature in the heating cavity outside the water, and a second temperature sensor that measures the water temperature inside the heating cavity. Additional temperature sensors may also be present. A pressure sensor is not strictly necessary for this control system.

[0062] In this embodiment, the device according to the invention preferably comprises a food cavity for holding food; a heating cavity with a water cavity for holding water; and a heating element for heating the water in the water cavity. It further includes a first temperature sensor, configured to detect the temperature inside the heating cavity but outside the water cavity, and a second temperature sensor, configured to detect the temperature inside the water cavity. The control device is configured to regulate the heating power of the heating element based on the data detected by the first and second temperature sensors. This prevents overpressure from persisting for an extended period and causing all the water to escape from the lunchbox.This also prevents the interior from cooling down too much and the resulting negative pressure from making it impossible to open the lunchbox.

[0063] The boiling point of the water is measured by the first temperature sensor located in the water. This allows conclusions to be drawn about the prevailing absolute internal pressure. Depending on its position and the progress of the heating process, the second temperature sensor measures the temperature in the water vapor, in the vapor-air mixture, or in the air within the heating cavity.

[0064] Preferably, a food unit is provided, comprising a previously described container of the presented portable lunchbox and containing a food item. This food unit further includes a food unit lid to enclose the food item, preferably in a gas- and / or liquid-tight manner, between the container and the food unit lid. The food unit is placed in the lunchbox—possibly after removing packaging such as the food unit lid—with the food unit container replacing the lunchbox container. The food item in the food unit can then be heated and / or steamed as previously described. Particularly for foods suitable for steaming, the food unit container may have openings through which steam can pass. The bottom of the container may, for example, be designed as a rack.

[0065] Depending on the design, the container may have a single cavity or be divided. Each part of the unit could, for example, contain a different food item. Individual parts may be closed or open.

[0066] For example, a food unit can have two parts: the first part contains food that is not in contact with steam, and the second part contains food that is heated by steam. The two parts can be packaged so that they can be opened independently. For preparation, only the part containing the food to be steamed is opened, and the lunchbox is operated in the second position of the switching device. This allows the food in the opened part to be steamed, while the other part remains thermally insulated and is only heated. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Preferred embodiments of the invention are described below with reference to the drawings, which serve only for illustration and are not to be interpreted restrictively. The drawings show: Fig. 1 a perspective view of a lunchbox according to the invention in a first embodiment; Fig. 2 an exploded view of the lunchbox according to the invention. Figure 1 Fig. 3 shows a side view of the lunchbox according to Figure 1 ; Fig. 4 shows a cross-section through the lunchbox according to Figure 1 ; Fig. 5 an enlarged view of a section of the lunchbox according to Figure 4 Fig. 6 shows a side view of the lunchbox according to Figure 1 in a steaming mode; Fig. 7 a cross-section through the lunchbox according to Figure 6 ; Fig. 7a an enlarged view of a section of the lunchbox according to Figure 7 ; Fig. 8 a perspective view of a lunchbox seal according to Figure 1 ; Fig. 9 a view of a lid according to Figure 1from below without a seal; Fig. 10 a view of the lid of the lunchbox according to Figure 9 with the seal according to Figure 8 from below; Fig. 11 a perspective view of the bottom of the lunchbox according to Figure 1 with an inserted container; Fig. 12 a side view of the base with inserted container according to Figure 11 ; Fig. 13 a perspective view of the ground according to Figure 11 without container; Fig. 14 a view of the bottom according to Figure 13 from above; Fig. 15 a view of a circuit board of the lunchbox according to Figure 1 ; Fig. 16 a perspective view of a food unit for use in the lunchbox according to Figure 1 ; Fig. 17 a flowchart of the operation of the lunchbox according to Figure 1 Figure 18 shows a cross-section through a part of a lunchbox according to the invention in a second embodiment with the gas connection open; Figure 19 shows a cross-section through the part of the lunchbox according to Figure 18with closed gas connection; Figure 20 a view of the lid of the lunchbox according to Figure 18 from below; Figure 21 a cross-section through a part of a lunchbox according to the invention in a third embodiment with the gas connection open; Figure 22 a cross-section through the part of the lunchbox according to Figure 21 with closed gas connection; Figure 23 a perspective view of a switching element of the lunchbox according to Figure 21 Figure 24 shows another perspective view of a switching element of the lunchbox according to Figure 21 Figure 25 shows a cross-section through a part of a lunchbox according to the invention in a fourth embodiment with the gas connection open; Figure 26 shows a cross-section through the part of the lunchbox according to Figure 25with a closed gas connection; Figure 27 shows a cross-section through a part of a lunchbox according to the invention in a fifth embodiment with a closed gas connection; Figure 28 shows a cross-section through the part of the lunchbox according to Figure 27 with open gas connection; Figure 29 shows a cross-section through a part of a lunchbox according to the invention in a sixth embodiment with closed gas connection, and Figure 30 shows a cross-section through the part of the lunchbox according to Figure 29 with the gas connection open. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0068] Figure 1Figure 1 shows a perspective view of a lunchbox according to the invention. The lunchbox 1 shown has a lid 2 which is attached to a base 3 by fastening elements 5 in the form of hinged tabs. The lid 2 is preferably completely removable from the base 3, so that an opening in the base 3 is fully exposed. The tabs 5, 50 are preferably pivotally attached to the lid 2.

[0069] Two of the tabs are also designed as switching devices 50, which allow switching between a heating mode and a steaming mode. Preferably, a tab 5 is arranged on each side of the lid 2, with the larger, opposing tabs 50 on the longitudinal sides of the lid preferably being designed as switching devices. The tabs 50, which are designed as switching devices, are preferably configured as approximately right-angled elements. They preferably extend partially over the top surface of the lid 2, and when the lunchbox 1 is closed, they are preferably flush with the surface of the lid 2.

[0070] The lunchbox 1 is preferably approximately cuboid in shape. However, it can also have other shapes. Preferably, the base 1 is flat on its underside for resting on a table or it has corresponding feet. Preferably, the lunchbox 1 has no protruding elements when closed.

[0071] On the front of the lunchbox 1, in the base 3, there is a user interface 86 in the form of a push button, with which, for example, a heating process can be initiated, as well as two signal output units 84 in the form of LED lights, which can serve, for example, as status indicators or warning signals.

[0072] Figure 2Figure 1 shows an exploded view of lunchbox 1. A container 4 for holding food is arranged between the lid 2 and the base 3. The lid 2, the base 3, the container 4, and the tabs 5, 50 are preferably made of plastic. Parts of these components may also be made of metal or another material.

[0073] Container 4 defines a food cavity 10 for holding the food to be heated or, if applicable, cooked. The base 3 defines a heating cavity 20 for holding water for heating or steaming the food. A seal is arranged between the lid 2 on the one hand and the base 3 and container 4 on the other, comprising a first seal 40 and a second seal 30. The first and second seals 40, 30 can consist of two separate elements or they can be formed as a single piece. In this example, they are formed as a single piece.

[0074] Figure 3 Figure 1 shows a side view of Lunchbox 1 in its closed state. This state is used for transporting the lunchbox, storing food, and also for warming food without steam. This state will be referred to as the warming mode in the following.

[0075] Figure 4Figure 1 shows a cross-section of the lunchbox 1 in heating mode. The two tabs, designed as a switching device 50, are in a first, depressed state, so that they press the first seal 40 against a circumferential upper rim 43 of the container 4. This rim is in Figure 2 This is evident. As a result, the upper edge 43 is sealed all around, and a gas connection between the heating cavity 20 and the food cavity 10 is closed. No water vapor can enter the food cavity 10. Instead, the water vapor heats the outside of the container 4 and thus also the food (not shown) arranged in the container 4. In this first state of the switching device 50, food arranged in the food cavity 10 can therefore be heated. The water vapor is generated in the heating cavity 20, more precisely in a Figure 13 The depicted water cavity 21, which is part of the heating cavity 20.

[0076] The second seal 30 is pressed by the lower edge of the lid 2 against an upper edge 33 of the base 3 and seals the heating cavity 20, and thus also the food cavity 10, gas-tight to the outside, so that no contents, such as water vapor, water, or food, can leave the system. The upper edge 33 of the base 3 is in Figure 2 Clearly visible. This ensures the lunchbox is tightly sealed for transport. Furthermore, no odors can escape during storage or food preparation. The two seals (30, 40) provide double sealing, guaranteeing optimal leak protection.

[0077] The heating element 80 and other electronic components, such as a circuit board 89 to which the user interface 86 and the signal output unit 84 are connected, are arranged in an electronics cavity 70 of the base 3. The base 3 preferably has a lower cover which allows access to the electronics cavity 70, at least during assembly.

[0078] Figure 5 Figure 1 shows an enlarged section of a cross-section of the lunchbox 1 in heating mode. It is clearly visible that the tab, designed as a switching device 50, is pressed down, thus pressing the first seal 40 against the upper edge 43 of the container 4, thereby closing a gas connection between the heating cavity 20 and the food cavity 10.

[0079] Figure 6Figure 1 shows a side view of the lunchbox 1 in steaming mode. The two fastening elements 5, designed as a switching device 50, are in a second, raised state, in which they no longer secure the lid 2 to the base 3. However, the two other tabs 5 still close the lunchbox.

[0080] Figure 7 Figure 1 shows a cross-section of the lunchbox 1 in steaming mode. The two fastening elements 5, designed as a switching device 50, are in a second, raised state, so that they lift the first seal 40, for example via a mechanical connection 51 as shown, thereby opening a gas connection between the heating cavity 20 and the food cavity 10. Through this connection, steam, which is generated in the heating cavity 20 by the evaporation of water, can enter the food cavity 10 and steam the food placed there.

[0081] In this second state of the switching device 50, the second seal 30 is also pressed by the lower edge of the cover 2 against the upper edge 33 of the base 3 and seals the entire assembly of heating cavity 20 and food cavity 10 gas-tight to the outside, so that no water vapor can leave the system.

[0082] Figure 7a The figure shows the state with the tab raised and the gas connection open. The sealing wing 45 is raised together with the flap or tab 50. The upper edge 43 of the container 4 is exposed in the area of ​​the sealing wing 45, and the gas connection between the heating cavity 20 and the food cavity 10 is open. However, the second sealing ring 32 of the second seal 30 still rests on the upper edge 33 of the base 3 and seals outwards over the entire circumference of the base 3.

[0083] Figure 8Figure 1 shows the one-piece seal comprising the first seal 40 and the second seal 30. It is preferably made of silicone. The second seal 30 has a second sealing ring 32, which, in the orientation shown, projects downwards, but in the operating state is directed upwards, although it has a downward-facing sealing surface. The first seal 40 has a first sealing ring 42, which projects upwards, and two sealing wings 45, each of which has a mechanical connecting element attached. This connecting element allows the switching device to lift at least a part of the first seal 40, in particular the sealing wings 45. In this example, the mechanical connecting element is a rigid cuboid sleeve 51 made of plastic with a rigid pin 52 projecting from both sides. The central area 46 is empty, i.e., the seal is formed solely by a circumferential, self-contained annular structure.

[0084] Figure 9 Figure 2 shows the cover 2 from below. Its underside is marked with reference numeral 25. First structures 41 and second structures 31 are arranged on the underside of the cover 2. The first structures 41 are designed to interact with the first sealing ring 42 of the first seal 40, for example, to guide it, promote its correct seating, and / or improve its sealing properties. For example, the first structures 41 can have a first ledge projecting from the cover 2, against which the first sealing ring 42 of the first seal 40 rests. The structures preferably have two second ledges projecting from the cover 2, between which the first sealing ring 42 of the first seal 40 engages. The two second ledges preferably run substantially parallel to each other and are preferably formed close to each other, so that the first sealing ring 42 of the first seal 40 is clamped between them. Figure 10The one-piece seal 30, 40 is inserted.

[0085] The second structures 31 are designed to interact with the second sealing ring 32 of the second seal 30, for example, to guide it, promote its correct seating, and / or improve its sealing properties. The structures have, for example, a shoulder circumferential to the lid 2, against which the second sealing ring 32 of the second seal 30 can rest and which presses the second sealing ring 32 against the base 3 when the lunchbox is closed. In another embodiment, the second structures 31 have a ledge circumferential to the lid 2, against which the second sealing ring 32 of the second seal 30 rests and is pressed. In this example, the two structures 41 and 31 are two circumferential grooves.

[0086] Structures 53 are arranged on the two fastening elements 5 of the switching device 50, into which the connecting elements 51, 52 of the first seal engage. Receptacles 53 are provided for this purpose. When the fastening elements 5 are lifted, the connecting elements 51 and thus the adjacent part of the seal 40 are also lifted. This opens the gas connection between the heating cavity and the food cavity. When the fastening elements 5 are pushed down, the connecting elements 51 are also pushed down, thereby closing the gas connection between the heating cavity and the food cavity.

[0087] The Figures 11 and 12Figure 3 shows the base 3 with the container 4 inserted therein. The container 4 is designed as a recessed tray. It has a laterally projecting, flat rim that extends above the upper edge of the base 3 and preferably does not rest on it. A gap between the base 3 and the container 4 allows water vapor, generated in the water cavity 21 below the container 4, to rise through the heating cavity 20 between the base 3 and the container 4. Because the container 4 extends above the base 3, it can also be removed more easily.

[0088] Figure 16Figure 1 shows a preferred food unit 60 before use. It comprises a container 4 and a lid 65. The lid 65 is preferably made of a gas-tight film, which is detachably affixed to the upper rim of the container 4. Food items already prepared for heating or steaming can thus be placed in the container 4. The unit can therefore be offered to consumers in appropriate retail outlets. Depending on the type of food offered, the lid 65 is partially or completely removed before the container 4 is placed in the lunchbox, allowing steam to reach the food. However, it can also remain on the container 4 for other preparation methods.

[0089] Figure 13Figure 3 shows a perspective view of the base 3. The base 3 is designed to form the lower part of the heating cavity 20. A depression in the form of the water cavity 21 is recessed in the center of the base of the heating cavity 20. This cavity is designed to receive water to be evaporated. The edge of the water cavity 21 preferably has a circumferential ledge or other features that serve as an indicator of a maximum or preferred fill level. Inside the heating cavity 20, webs 22 are formed such that a container inserted into the base 3 remains at a distance, allowing water vapor to rise between the base 3 and the container. As shown, the base 3 of the heating cavity 20 can be sloped, preferably so that water and condensate located on the base 3 of the heating cavity 20 can flow back into the water cavity 21.The heating element 80 is preferably arranged on or below the water cavity 21.

[0090] Figure 14 Figure 3 shows the base 3 from above. Preferably, a recess is formed in the base 3 in which at least one first temperature sensor 95 and / or a cable connection between a first temperature sensor 95 and the circuit board 89 located inside the base 3 is arranged. This first temperature sensor 95 can also be located within the water cavity 21. Preferably, however, it is located in the area of ​​the heating cavity, where it comes into contact with air and / or water vapor and / or an air / water vapor mixture.

[0091] In some embodiments, a second temperature sensor 96 is provided, which is preferably arranged in the water cavity 21 and thus lies in the water. If both temperature sensors 95, 96 are present, a pressure sensor is not provided, depending on the embodiment. The second temperature sensor is in Figure 13recognizable.

[0092] Figure 15 Figure 89 shows the circuit board 89 of the lunchbox, preferably arranged in the electronics cavity. The circuit board 89 includes, for example, the user interface 86 (e.g., in the form of the aforementioned push button), a control device 85, the signal output unit 84 (in the form of at least one LED), a power connection 82, and at least one pressure sensor 90. The circuit board 89 has a recess in its center into which the water cavity 21 of the base 3 can engage. The circuit board 89 preferably has a connection for controlling and / or supplying power to the heating element 80 and / or a connection to a battery and / or a mains power supply.

[0093] The circuit board 89 is preferably arranged so that it is in contact with the environment of the lunchbox, allowing the pressure sensor 90 to detect the ambient pressure. For this purpose, it is sufficient, for example, that the lower part of the lunchbox is not airtight. This allows the control unit 85, which may include a database, e.g., in an EEPROM (not shown), to define a minimum required temperature and / or a maximum permissible temperature in the heating cavity. This temperature can be monitored by the first temperature sensor 95 located in the heating cavity, and the heating power of the heating element 80 can be controlled accordingly.

[0094] Figure 17Figure 1 shows a possible flowchart for operating the lunchbox. In step 100, the device, i.e., the lunchbox, is in a standby mode in which energy consumption is minimized. In step 101, the device is activated, for example, by pressing the user interface button 86, so that the device is ready in step 102. This can be signaled to the user, for example, by the signal output unit 84, e.g., in the form of a green indicator light.

[0095] If no further commands are entered via the user interface for a predefined time t, the device automatically switches back to standby mode in step 103 to save power. However, if the user initiates a heating process, as shown in step 104, the heating process is initialized in step 105. During this step, the actual ambient air pressure is measured, and a maximum target internal pressure is calculated from the measurement. In the next step, 106, the heating process starts, activating the heating element. If there is water in the heating cavity, water vapor is generated, either for heating or steaming food in the food cavity. A heating timer is also started. The activation of the heating element can be indicated to the user, for example, by a red light signal from the signal output unit 84.

[0096] During the heating process, the internal parameters, i.e., the temperature of the water or water vapor inside the lunchbox, are queried and monitored, e.g., continuously, periodically, or at set intervals (step 107). Based on the measured temperature, the actual air pressure can be determined, e.g., using a water vapor table, and compared with the target internal air pressure set in step 105.

[0097] If the actual indoor air pressure is higher than the maximum target indoor pressure, the heating element is switched off in step 108, and a message is sent to the user in step 109, for example, via a flashing red warning signal. If the user does not respond within a certain period, the device can be returned to standby mode in step 110. However, if the user opens and closes the heating chamber in step 111, thus equalizing the pressure, the device can be returned to an operational mode from which the user can restart it.

[0098] As long as the actual indoor air pressure is less than or equal to the maximum target indoor pressure and the heating timer has not yet expired, the device is reinitialized, e.g., periodically or at set intervals. In step 114, the actual outdoor air pressure is measured again, and the maximum target indoor air pressure in the boiler room, i.e., in the heating cavity, is calculated. If the heating timer expires, the heating element is switched off in step 113, and a corresponding message is sent to the user, e.g., via a flashing green signal. The device can be configured to then automatically switch back to standby mode.

[0099] In the embodiment which has the first temperature sensor 95 outside the water and the temperature sensor 96 in the water, the control unit can be used to monitor and, depending on the variant, to control the tightness. This embodiment is preferably combined with the variant in which the outer seal becomes leaky or opens above a certain pressure difference between the internal and external pressure.

[0100] In the first scenario, heating is performed at maximum power. The absolute internal pressure no longer increases beyond a defined relative pressure because the outer seal leaks and the heating cavity is no longer airtight. The stable absolute internal pressure is determined using the temperature measured by the second temperature sensor 96, i.e., the measured water temperature. The first temperature sensor 95 measures the temperature outside the water, i.e., the temperature of the air / steam mixture. Heating continues at maximum power until the temperature measured by the first temperature sensor 95, i.e., the internal temperature, is approximately equal to the water temperature. From this point on, it can be assumed that the air has partially or completely escaped from the lunchbox. The heating power is then reduced to allow the outer seal to close again and the heating cavity to become airtight once more.

[0101] In another variant, the heating power is reduced shortly after reaching the absolute internal pressure, which would subsequently lead to leakage of the heating cavity.

[0102] The switching device, which enables or closes a gas connection between the heating cavity and the food cavity, can be designed in various ways. Accordingly, the seals, the shape of the lid, and, if applicable, the shape of the upper part of the base can also be designed differently. Some examples of how the switching device can be designed are given below. The parts of the lunchbox according to the invention that are not described or shown preferably correspond to the components according to the first embodiment shown and described in detail above.

[0103] The embodiments described below have the advantage of minimizing the manufacturing costs of the lunchbox. These embodiments feature a lid 2 that closes a base 3. The lid 2 can be completely separate from the base 3 or hinged to it. The lid 2 is preferably lockable in its closed position to allow the lunchbox to be transported. These closures are not shown below. For example, flaps and tabs like those in the first example can be used, without requiring a switching function for toggling between steaming and heating.

[0104] In the Figures 18 to 20 A second embodiment of the lunchbox according to the invention is shown. The lid 2 no longer has tabs or flaps as a switching device; instead, the lid 2 itself forms the switching device. For this purpose, it is designed asymmetrically. As in Figure 20As can be seen, it has two circumferential sealing rings 32, 42, wherein the inner sealing ring 42 has a greater distance to the outer sealing ring 32 on one longitudinal side of the cover 2 than on the opposite longitudinal side. Along the two other longitudinal sides, the two sealing rings 32, 42 preferably run at a constant distance from each other. Preferably, the different distance is present along the longer longitudinal sides. The cover 2 preferably has a rectangular base shape. However, other shapes are also possible as long as the cover 2 can be placed on the base 3 in two different, well-defined positions.

[0105] The base 3 has a circumferential upper edge 33, which is also not symmetrical. As in the Figures 18 and 19 It can be seen that the edge 33 is longer on one longitudinal side than on the other side.

[0106] The lid 2 can be placed in a first switching position onto the upper edge 33 of the base 3. In this position, the outer sealing ring 32 seals against a protruding flange of the base 3. The inner sealing ring 42 has no sealing function. The upper edge 43 of the container 4 is not sealed. The gas connection between the food cavity 10 and the heating cavity is open. It runs between the side walls of the base 3 and the container 4. The lunchbox is ready for steaming.

[0107] In Figure 19 The lid 2 is now in place rotated 180°, i.e., in a second switching position. The outer sealing ring 32 still rests on the upper edge 33 of the base 3, sealing all the way around. Now, however, the inner sealing ring 43 also rests on the upper edge 43 of the container 4, sealing all the way around. The gas connection between the food cavity 10 and the heating cavity is closed. The lunchbox is ready for heating.

[0108] In the Figures 21 to 24 A further embodiment of the lunchbox according to the invention is shown. The switching device has at least one, preferably two or more, switching levers 6. As in the previous example, the lid 2 has a downward-facing outer sealing ring 32 and an inner sealing ring 42, also facing downwards. Each of the two sealing rings 32, 42 completely surrounds the lid 2, with their distance from each other and preferably also their distance from the edge of the lid remaining constant over the entire circumference. The container 4 preferably also has a constant rim, in contrast to the previous example.

[0109] The cover 2 is penetrated by at least one, here by two, shift levers 6. The shift levers 6 run between the inner sealing ring 42 and the outer sealing ring 32, as shown in the Figures 21 and 22 is clearly visible.

[0110] By changing the position of the shift lever 6, the container 4 can be raised until its upper edge 43 rests against the inner sealing ring 42 and is thus sealed all around. This raising closes the gas connection. The open steam position is in Figure 21 The closed heating position is shown. Figure 22 .

[0111] The at least one switching lever 6 can be designed differently. Preferably, it can be moved from the steam position to the heating position and vice versa by vertical displacement and / or by a rotary movement, whereby this movement lowers and raises the container 4. An example of the switching lever 6 is shown in the Figures 23 and 24It is recognizable. It has a handle 66, which is arranged on an upper head 67. The head 67 is arranged on a shaft 68, the free end of which terminates in a downwardly sloping cam 69. By turning the handle 66, the cam 69, which is located below the upper edge 43 of the container 4, rotates. The upper edge 43 is engaged during rotation and carried upwards.

[0112] In the Figures 25 and 26 Another example is provided. Here too, the lid 2 has an inner sealing ring 42 and an outer sealing ring 32, both of which are directed downwards and seal against the upper edge 43 of the container 4 and the upper edge 33 of the base 3, respectively. They are again formed completely around the circumference and preferably have the same distance from each other over their entire circumference.

[0113] In this example, the cover 2 is designed in two layers, with an outer cover plate 26 and an inner cover plate 27. The outer sealing ring 32 is arranged on the outer cover plate 26, the inner sealing ring 42 on the inner cover plate 27. The two plates 26, 27 are arranged to be slidably relative to each other in the vertical direction, so that the distance between the inner cover plate 27 and the outer cover plate 26 can be changed.

[0114] In the raised switching position, only the outer sealing ring 32 rests against the upper edge 33 of the base, providing a circumferential seal. The inner cover plate 27 is raised, and the inner sealing ring 42 therefore terminates at a distance from the upper edge 43 of the container 4. The gas connection is open, and the lunch box is ready for steaming. This is in Figure 25 recognizable.

[0115] In Figure 26The inner lid plate 27 is lowered and the inner sealing ring 42 rests on the upper edge 43 of the container 4, sealing the container interior 10 all around to the base 3. The gas connection is closed and the lunchbox is ready for heating.

[0116] The switching device for moving the two cover plates 26, 27 can be designed differently. In this example, a sliding knob 29 is provided that raises and lowers the inner cover plate 27. Preferably, the sliding knob can be changed in position linearly or by a rotary movement.

[0117] In the embodiment according to the Figures 27 and 28The container 4 is tightly sealed with a separate container lid 7. A circumferential container sealing ring 71, oriented upwards, is arranged on this lid 7. Instead of a soft sealing ring 71, a circumferential raised section can also be present, forming a sealing seat. Alternatively, the container lid 7 can simply be sufficiently thick to form a sealing seat. The counterpart to this seal is the downward-facing inner sealing ring 42, which is arranged on the lid 2. If the container lid 7 has a sealing ring, the lid 2 can also form a suitable sealing seat instead of the inner sealing ring 42.

[0118] The lid 2 in turn has the downward-facing outer sealing ring 32, which seals the lunchbox tightly to the outside by resting on the upper edge 33 of the base 3 in a sealing manner all around.

[0119] In Figure 27Container 4 is sealed with the container lid 7. Therefore, there is no gas connection to the interior 10. The lunchbox is ready to be heated.

[0120] In Figure 28 Container lid 7 has been removed, thus opening container 4. The gas connection is open and the lunchbox is ready for steaming.

[0121] Depending on the embodiment, the container lid 7 is either reusable or used as a disposable part. The container lid 7 forms the switching device, particularly when it is reusable.

[0122] In the Figures 29 and 30Another embodiment is shown. The lid 2 has a circumferential, downward-facing sleeve 28. The outer sealing ring 32 is not attached to the lid 2, but is held in a corresponding receptacle on the side walls of the container 3 or is integrally formed with it. The sleeve 28 covers the outer sealing ring 32, so that the lunchbox is tightly sealed to the outside. The inner sealing ring 42 is still attached to the lid 2 and projects downwards. In the closed state, the inner sealing ring 42 rests against the upper edge 43 of the container 4, sealing it in place. The gas connection is interrupted, and the lunchbox can only be used for heating. Figure 29 recognizable.

[0123] When the lid 2 is lifted, the inner sealing ring 32 releases the upper edge 43 of the container 4 and the gas connection is open. The lunchbox can then be used for steaming. This is in Figure 30recognizable. The lunchbox is still completely sealed to the outside, since the sleeve 28 of the lid 2 has been moved along the outer sealing ring 43, but is still in contact with it.

[0124] The lid 2 can be moved in various ways. For example, it can be moved manually. However, the upward movement can also be achieved using the steam generated in the device. In both cases, a locking mechanism is preferably provided to prevent the lid 2 from being lifted when only the heating function is to be used. The usual clamping devices or other known elements can be used as locking mechanisms. The switching device is again the lid 2 itself.

[0125] The inventive lunchbox is easy to manufacture, robust and cost-effective, and it allows for a variety of ways to prepare food in a simple manner. REFERENCE MARK LIST

[0126] 1 Lunchbox 45 Sealing wing 2 Lid 46 Empty space 3 Floor 50 Switching device 4 container 51 sleeve 5 Fastener 52 Pen 6 gearshift lever 53 Recording 7 Container lid 60 Food unit 10 Food cavity 65 Food unit 20 Heating cavity Lid 21 Water cavity 66 Handle 22 footbridges 67 Head 25 Underside of the lid 68 shaft 26 outer cover plate 63 backdrop 27 inner cover plate 70 Electronics cavity 28 Coat 71 Container sealing ring 29 sliding button 80 heating element 30 second seal 82 power connection 31 second structures 84 Signal output unit 32 second sealing ring 85 Control device 33 upper edge of the ground 86 User Interface 40 first seal 89 circuit board 41 first structures 90 Pressure sensor 42 first sealing ring 95 first temperature sensor 43 upper edge of the container 96 second temperature sensor

Claims

1. Device for preparing food, comprising - a food cavity (10) for receiving food; - a heating cavity (20) for receiving water; - a heating element (80) for heating water in the heating cavity (20); characterized in that the device comprises - at least one pressure sensor (90) which is designed to detect a pressure surrounding the device (1); - a first temperature sensor (95) designed to sense a temperature within the heating cavity (20); and - a control device (85) designed to control a heating power of the heating element (80) in dependence on the data detected by the pressure sensor (90) and the first temperature sensor (95).

2. Device according to claim 1, wherein the at least one pressure sensor (90) is arranged fluidically separately from the food cavity (10) and the heating cavity (20).

3. Device according to any one of claims 1 or 2 wherein the pressure sensor (90) is arranged in a cavity which is separate from the food cavity (10) and from the heating cavity (20) and which is in pressure connection to the environment of the device.

4. Device according to any one of claims 1 or 2 wherein the pressure sensor is arranged on an outside of the device.

5. Device according to any one of claims 1 to 4 wherein the temperature sensor is arranged in the heating cavity.

6. Device according to any one of claims 1 to 5 wherein the control unit is designed to switch off the heating element after a defined heating period.

7. Device according to any one of claims 1 to 6 wherein it is a portable lunchbox (1 for storing, transporting and preparing food comprising - the food cavity (10) for receiving food, - the heating cavity (20) for receiving water, - the heating element (80) for heating water in the heating cavity (20).

8. Device according to claim 7 wherein the lunchbox comprises a switch device (50) which can be switched from a first state to a second state, and wherein the lunchbox (1) is designed - in the first state of the switch device (50) to heat food arranged in the food cavity (10), and - in the second state of the switch device (50) to steam food arranged in the food cavity (10), wherein the switch device (50) in the first state closes a gas connection between the heating cavity (20) and the food cavity (10) and in a second state, opens a gas connection between the heating cavity (20) and the food cavity (10).

9. Device according to claim 8 comprising a first seal (40), wherein - in the first state of the switch device (50), the first seal (40) seals the food cavity (10) in a gas-tight manner with respect to the heating cavity (20), and - in the second state of the switch device (50), the switch device (50) at least partially releases the first seal (40) so that the food cavity (10) and the heating cavity (20) are gas-connected to each other.

10. Device according to any one of claims 1 to 9 wherein the device comprises a second temperature sensor (96) designed to detect a temperature within the water cavity (21), and wherein the control device (85) is designed to control a heating power of the heating element (80) in dependence on the data detected by the first and second temperature sensors (95, 96).

11. Method for operating the device according to any one of claims 1 to 10, wherein water in the heating cavity (20) is heated by means of the heating element (80), wherein the pressure surrounding the device is detected by means of the pressure sensor (90), wherein the temperature within the heating cavity (20) is detected by the first temperature sensor (95), and the heating power of the heating element (80) is controlled by the control device (85) as a function of the data detected by the pressure sensor (90) and the first temperature sensor (95).

12. Method according to claim 11, wherein the ambient pressure is measured at the start of or during the heating process, wherein a minimum temperature is determined from the measured ambient pressure, and wherein the heating element is operated such that, during the heating process, the temperature measured in the heating cavity remains above the minimum temperature.

13. A method according to any one of claims 11 or 12, wherein the ambient pressure is measured at the start of or during the heating process, wherein a maximum temperature is determined from the measured ambient pressure, and wherein the heating element is operated such that, during the heating process, the temperature measured in the heating cavity remains below the maximum temperature.

14. Device for preparing food, comprising - a food cavity (10) for receiving food; - a heating cavity (20) with a water cavity (21) for receiving water; - a heating element (80) for heating water in the water cavity (21); characterized in that the device comprises - a first temperature sensor (95) designed to detect a temperature inside the heating cavity (20) but outside the water cavity (21); - a second temperature sensor (96) designed to detect a temperature inside the water cavity (21); and - a control device (85) designed to control a heating power of the heating element (80) in dependence on the data detected by the first and second temperature sensors (95, 96).

15. Device according to claim 14, wherein at least the heating cavity (20) is sealed with respect to the outside by a seal (32), and wherein the seal (32) opens or leaks at a defined pressure difference between the interior of the heating cavity (20) and the outside.