SELF-HEATING CONTAINER FOR FOOD

Abstract

A container made from an electrically insulating material whose walls are functionally connected to a temperature sensor and incorporate heating groups consisting of a plurality of elongate metal elements; should the container be made from glass, the coefficient of thermal expansion of the heating groups is similar to that of glass. The container is functionally associated with an electronic power and control module, connected to the heating groups and comprising a rechargeable energy accumulator of a type with one or several high-performance cells. The metal elements are heated by Joule effect by the flow of a pulsed current provided by the energy accumulator and controlled by the electronic power and control module.

Claims

1-14. (canceled)

15. A self-heating container for food comprising: a vessel made from an electrically insulating material comprising one or more walls that are functionally connected to at least one temperature sensor and incorporate heating groups comprising a plurality of thread-like, ribbon-like or a combination of thread-like and ribbon-like elongate metal elements; and an electronic power and control module, functionally connected to said heating groups and comprising a rechargeable energy accumulator comprising one or several high-performance cells; wherein said elongate metal elements are heated by Joule effect, causing a pulsed current supplied by said rechargeable energy accumulator and controlled by said electronic power and control module to flow through the elongate metal elements, the latter comprising: a microcontroller; a power control circuit for controlling power transferred from the rechargeable energy accumulator to the elongate metal elements; a measurement conditioning circuit which transfers a temperature value assessed by said at least one temperature sensor to said microcontroller; an energy accumulator management circuit for controlling the rechargeable energy accumulator, which an energy accumulator management circuit comprises at least one integrated circuit, electronically interfaced to said microcontroller and electrically connected between a power source and said rechargeable energy accumulator; and a user interface for exchanging information with said microcontroller.

16. The container according to claim 15 wherein said elongate metal elements comprise a coefficient of thermal expansion, wherein the coefficient of thermal expansion of the elongate metal elements is the same as the coefficient of expansion of the material that said vessel is made from.

17. The container according to claim 15 wherein said vessel is made from glass.

18. The container according to claim 16 wherein said vessel is made from glass

19. The container according to claim 18 wherein the coefficient of thermal expansion of said elongate metal elements ranges from 2 to 10 m/m C.

20. The container according to claim 19 wherein said coefficient of thermal expansion of said elongate metal elements equals 8 m/m C.

21. The container according to claim 15 wherein the heating groups comprise an impedance, wherein further said measurement conditioning circuit measures the impedance of said heating groups.

22. The container according to claim 15 wherein a lid is functionally associated with said vessel, such lid operating, via sliding contacts, as an intermediary for an electrical interconnection between the heating groups, the temperature sensor and the electronic power and control module, thus implementing a reversible, on or off, plug-in coupling.

23. The container according to claim 22 wherein said lid comprises spring small pistons.

24. The container according to claim 15 wherein an identifying resistor, having a predetermined value as a function of the type of container, is associated therewith, and wherein said identifying resistor is electrically connected to the electronic power and control module which identifying resistor is capable of determining its value by measuring the voltage drop that is created across it by way of a resistive divider.

25. The container according to claim 24 wherein a lid is functionally associated with said vessel, such lid operating, via sliding contacts as an intermediary for an electrical interconnection between the heating groups, the temperature sensor, the identifying resistor and the electronic power and control module, thus implementing a reversible, on or off, plug-in coupling

26. The container according to claim 15 comprising an accelerometer functionally connected to said microcontroller.

27. The container according to claim 15 wherein said power control circuit comprises a DC-DC converter of a reducer-elevator type.

28. The container according to claim 27 wherein said DC-DC converter comprises a proportional-integrative-derivative (PID) regulator and a pulse width modulator (PWM).

29. The container according to claim 28 comprising an EEPROM memory and wherein the card of the electronic power and control module comprises a circuit built according to the 1 wire technology for reading out said EEPROM memory.

30. The container according to claim 29 wherein a lid is functionally associated with said vessel, such lid operating, via sliding contacts as an intermediary for an electrical interconnection between the heating groups, the temperature sensor, the EEPROM memory and the electronic power and control module, thus implementing a reversible, on or off, plug-in coupling.

31. The container according to claim 15 comprising an electronic Bluetooth module interfacing to said microcontroller.

32. A self-heating container for food comprising: a vessel made from an electrically insulating material comprising one or more walls that are functionally connected to at least one temperature sensor and incorporate heating groups comprising a plurality of thread-like, ribbon-like or a combination of thread-like and ribbon-like elongate metal elements, wherein said elongate metal elements comprise a coefficient of thermal expansion, wherein the coefficient of thermal expansion of the elongate metal elements is the same as the coefficient of expansion of the material that said vessel is made from, wherein the heating groups comprise an impedance; an electronic power and control module, functionally connected to said heating groups and comprising a rechargeable energy accumulator of a type with one or several high-performance cells; wherein said elongate metal elements are heated by Joule effect, causing a pulsed current supplied by said rechargeable energy accumulator and controlled by said electronic power and control module to flow through the elongate metal elements, the latter comprising: a microcontroller; a power control circuit for controlling power transferred from the rechargeable energy accumulator to the elongate metal elements; a measurement conditioning circuit which transfers a temperature value assessed by said at least one temperature sensor to said microcontroller and measures the impedance of said heating groups; an energy accumulator management circuit for controlling the rechargeable energy accumulator, wherein the energy accumulator management circuit comprises at least one integrated circuit, electronically interfaced to said microcontroller and electrically connected between a power source and said rechargeable energy accumulator; a user interface for exchanging information with said microcontroller; wherein a lid is functionally associated with said vessel, such lid operating, via sliding contacts as an intermediary for an electrical interconnection between the heating groups, the temperature sensor and the electronic power and control module, thus implementing a reversible, on or off, plug-in coupling.

33. A self-heating container for food comprising: a vessel made from an electrically insulating material comprising one or more walls that are functionally connected to at least one temperature sensor and incorporate heating groups comprising a plurality of thread-like, ribbon-like or a combination of thread-like and ribbon-like elongate metal elements, wherein said elongate metal elements comprise a coefficient of thermal expansion, wherein the coefficient of thermal expansion of the elongate metal elements is the same as the coefficient of expansion of the material that said vessel is made from; an electronic power and control module, functionally connected to said heating groups and comprising a rechargeable energy accumulator of a type with one or several high-performance cells; an identifying resistor, having a predetermined value as a function of the type of container, which identifying resistor is electrically connected to the electronic power and control module, wherein the identifying resistor is capable of determining its value by measuring the voltage drop that is created across it by way of a resistive divider; wherein said elongate metal elements are heated by Joule effect, causing a pulsed current supplied by said rechargeable energy accumulator and controlled by said electronic power and control module to flow through the elongate metal elements, the latter comprising: a power control circuit for controlling power transferred from the rechargeable energy accumulator to the elongate metal elements; a measurement conditioning circuit which transfers a temperature value assessed by said at least one temperature sensor to said microcontroller; an energy accumulator management circuit for controlling the rechargeable energy accumulator, which energy accumulator management circuit comprises at least one integrated circuit, electronically interfaced to said microcontroller and electrically connected between a power source and said rechargeable energy accumulator; a user interface for exchanging information with said microcontroller; wherein a lid is functionally associated with said vessel, such lid operating, via sliding contacts as an intermediary for an electrical interconnection between the heating groups, the temperature sensor, the identifying resistor and the electronic power and control module, thus implementing a reversible, on or off, plug-in coupling.

34. The container according to claim 32 wherein said vessel is made from glass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIGS. 1 thru 3 show some possible embodiments of the metal resistive elements: a spiral wound about the walls, a dual spiral, used for the bottom of the container, and a heating coil arranged along a wall.

[0042] FIG. 4 shows a general block diagram of the electronic card of the power and control module (1). The following component parts are shown therein: [0043] (11) a microcontroller; [0044] (12) an energy accumulator management circuit; [0045] (13) a transferred power regulator circuit; [0046] (14) a measurement conditioning circuit; [0047] (16) a rechargeable accumulator () temperature sensor; [0048] (17) an EEPROM memory reader circuit; [0049] (19) a Bluetooth circuit.

[0050] The same figure also shows: [0051] (2) heating elements; [0052] (3) a connection for making it possible to reload the rechargeable electric energy accumulator (3) from an external source; [0053] (4) a container temperature sensor; [0054] (5) an identifying resistor; [0055] (6) an EEPROM memory; [0056] (7) an accelerometer; [0057] (8) a user interface; [0058] (9) an electric power source as necessary to recharge the energy accumulator (3).

[0059] FIG. 5 shows a circuit diagram of an electronic switch mounted in the power regulator circuit (13), which is controlled by the microcontroller via a proportional, integrative, derivative (PID) digital regulator. The figure shows: [0060] (3) the rechargeable electric energy accumulator; [0061] (32) a reducer stage electronic switch; [0062] (33) a reducer stage electronic switch (32) drive; [0063] (34) an inductor for the elevator and reducer stage function; [0064] (35) an elevator stage electronic switch; [0065] (36) an elevator stage electronic switch (35) drive; [0066] (37) a smoothing capacitor; [0067] (2) the heating elements.

[0068] FIG. 6 shows a further possible configuration of the invention shaped like a self-heating baby bottle.

[0069] FIG. 7 shows a further possible configuration of the invention shaped like a self-heating tray.

[0070] FIGS. 8 and 9 show two exploded views of a container with a power module laterally coupled therewith.

[0071] FIGS. 10 and 11 show two perspective, assembled views of a container with a power module laterally coupled therewith; FIG. 10 also shows the spirals of the metal elements (21) of the heating groups (2).

[0072] FIG. 12 shows an exploded view of a container wherein the power module is coupled via the lid. The electronic power module (1) can be coupled with the container via the lid, which an electrical interconnection disc (10) has been glued to, the latter providing the connections between the devices present in the walls of the container and the electronic power and control module (1). The connection between the power module (1) and the lid takes place reversibly via metal pivots and small pistons; the disc (10) along with the pivots is integrally connected to the lid underneath, whereas the cylinder positioned on the top forms the power module (1) with a user interface (8) integrated therewith on the top. The power module can be reversibly coupled with the assembly formed of the lid and the disc (10) along with the electrical connections.

[0073] FIG. 13 shows the underneath part of the power module (1), the disc (10) accommodating the electrical connections being integrally applied to the lid of the container.

[0074] FIG. 14 shows a cross-sectional view of a container wherein the power module is coupled with via the lid, as illustrated in FIG. 12, where a detail of the sliding contacts is shown in particular.

[0075] FIG. 15 shows a block diagram of a proportional, integrative, derivative (PID) digital controller; the functions performed by this controller are performed by the microcontroller (11), which interfaces to the container temperature sensor (4) and to the power regulator (13), which is in turn functionally connected to the heating elements (2).

[0076] The microcontroller (11) sets the temperature value to be reached, as a function of the required temperature/time, Celsius degrees/seconds thermal profile, via the Setpoint_Temp variable, and simultaneously measures the temperature reached in that moment, thus outputting the T feedback _Temp, temperature signal. An error variable, e(t), is generated on the basis of the difference between the set value and the measured value and processed by the power regulator to generate a duty duration D, i.e. the duration of the ON pulses to be applied to the electronic switch in order to increase or decrease the power transferred to the heating elements.

[0077] The power regulator thus allows to control the power transferred to the food in every instant and allows to continuously and precisely follow the desired temperature-time thermal profile by changing the temperature setpoint value.

[0078] During transfer of energy, the microcontroller (11) also controls the operating range and the conditions of the battery element in order for the process to take place regularly and ends either because it reaches the preset temperature or because the battery exhausts or an abnormality occurs.

DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

[0079] The electronic power and control module (1), besides supplying electric power, also modulates the duration of the voltage pulses across the metal elements (21), so as to proportionate the instant electric power as necessary to regulate the thermal power to be transferred to the walls of the vessel continuously and homogeneously, so as to obtain a controlled heating of its contents, according to preset thermal profiles.

[0080] The metal elements (21) of the heating groups (2) can be deposited or glued to the outside of the vessel, instead of being incorporated inside the walls of the container, the principle of operation of the device being unchanged; the distribution of the metal elements (21) can have different arrangements depending on the resistance values to be implemented and on the geometry of the vessel to heat.

[0081] According to one preferred embodiment, the walls of the vessel include appropriate spaces, preset during the moulding process, wherein at least one temperature sensor (4) is accommodated and interfaced to the power and control module (1); however, the temperature sensor might also be directly installed on the control device, so that the sensor gets in contact with the container whenever the control device is coupled with the container.

[0082] The temperature sensor (4), which is for instance a thermoresistor, precisely assesses the temperature of the wall of the container, by way of a special measurement conditioning circuit (14) in the electronic card, and communicates it to the microcontroller (11) in the electronic card of the power and control module (1), so that the latter can monitor the amount of heat that is transferred during the complete heating step, so as to accurately follow temperature/time thermal profiles; also, temperature assessing allows to prevent the container from reaching too high temperatures, which might spoil its contents and be harmful for users.

[0083] According to one particularly complete embodiment, an EEPROM memory (6), i.e. a non-volatile type of memory, as used in electronic devices for storing small amounts of data to be stored whenever electric power is switched off, might also be accommodated in the walls of the vessel. Data related to the food contained in the container, for example the name of the food producer, the packaging date, the expiration date, and the like, can be stored in this memory element. Also, if the EEPROM memory (6) is functionally connected to the power and control module (1), for example via a readout circuit (17) or directly via a built-in circuit present in the microcontroller (11), information might be easily stored therein, which might be taken advantage of during the heating step, such as for instance the thermal profile to be used, the maximum power level usable, the type of container, and the like.

[0084] The electronic power and control module (1) comprises at least a rechargeable electric energy accumulator (3) and an electronic control card, which in turn comprises a plurality of circuits and at least one microcontroller (11) which performs a supervisory function on all different operating steps of the device.

[0085] The electronic power and control module (1) possibly comprises a user interface (8), and the latter can comprise, in turn, a keyboard, possibly in a reduced-size format, with LEDs and/or a small display and/or other input/output devices of a known type.

[0086] According to a particularly advantageous embodiment, the rechargeable electric power accumulator (3) comprises one or several lithium cells connected in series and/or in parallel to each other.

[0087] Lithium cells provide very high discharge currents, which allow to supply extremely high powers levels within short times; however, these batteries are more complex to manage than dry batteries, nickel cadmium batteries or similar batteries, and consequently they need dedicated functions and electronic circuits in order for them to be managed in all steps of their service life.

[0088] The electronic control card of the power and control module (1) comprises at least the following different sections: [0089] an energy accumulator (3) management circuit (12); [0090] a transferred power control circuit (13); [0091] a measurement conditioning circuit (14) with a connection control circuit integrated therein.

[0092] In one particularly performing embodiment of the invention, the control card also comprises one or more of the following further sections: [0093] a user interface (8) control circuit, integrated in the user interface (8) or in the microcontroller (11); [0094] an accelerometer (7) measurement circuit integrated in the microcontroller (11); [0095] an EEPROM memory (6) readout circuit (17); [0096] a Bluetooth circuit (19).

[0097] The power and control module (1) is implemented in different power configurations as a function of the dimensions of the application, i.e., for example, as a function of the dimensions of the container and as a function of the required temperature gradient.

[0098] The energy accumulator (3) management circuit (12) is capable of analysing the conditions of the battery and evaluating the amount of charge stored, hence the residual energy available, on the basis of voltage, current, and temperature measurements; accumulator (3) temperature measurement can take place via a specifically developed sensor (16).

[0099] Also, the circuit (12) controls the charging step, account being taken of different important issues for a correct use of the battery, such as equalization of the voltages in the individual cells, amount of current drained, temperature, and charge calculation for determining when full autonomy is reached; also, the accumulator (3) management circuit (12) evaluates whether the accumulator (3) is efficient or not, and prevents it from being used in the case of abnormalities.

[0100] Low cost integrated control circuits, commonly referred to as chips, are by now present in the control integrated circuit market for this type of function, which perform all of the necessary functions and are capable of interfacing to the microcontroller (11); the latter supervises the energy accumulator (3) during the discharge step and stops it in the case of an abnormality or whenever the accumulator reaches the exhausted condition; as a matter of fact, cells shall not be discharged beyond a minimum voltage value, in order not to cause irreversible phenomena which would damage them.

[0101] The transferred power regulator circuit (13) allows to transfer electric power from the energy accumulator (3) to the heating groups (2). According to one particular advantageous solution, a DC-DC converter of a reducer-elevator converter type, also called Buck-Boost converter, is used, an outstanding characteristic of which is in that it can output a voltage greater or lower than that measured across the battery.

[0102] With reference to FIG. 5, let's note that, in this type of DC-DC converter, modulating the on and off statuses of the electronic switch (32) allows to get an output voltage Vout lower than the input battery voltage Vin, thus performing a reducer function; conversely, in this DC-DC converter, modulating the on and off statuses of the switch (35) allows to get an output voltage Vout greater than the input battery voltage Vin, thus performing an elevator function.

[0103] If these pulses are modulated at frequencies in the order of some kHz, the voltage is varied, and consequently the instant power applied to the heating elements can also be varied, thus controlling the container temperature.

[0104] The microcontroller (11) compares the desired temperature value to the value assessed by the temperature sensor (4) via the measurement conditioning circuit (14) and then generates an error function, e(t); the latter, via a proportional-integrative-derivative regulator, generates a duty cycle of the on-off pulses to be applied to the electronic switch in order to increase or decrease the power transferred to the heating elements.

[0105] The function performed by the measurement conditioning circuit (14) is to convert the analog quantities to be measured, such as voltages, currents, temperatures, and accelerations, within the range of voltage values accepted by the analog/digital converter present in the microcontroller (11), which is usually 0 to 3 V, in order to transform a physical quantity into a binary digital value subsequently used by the microcontroller for calculations and regulations.

[0106] The measurement conditioning circuit (14) is formed of operational amplifiers and resistors, so that, for example, the battery voltage, a value variable in a range from 10 to 30 V, is converted into a range from 0 to 3 V, or in such a way that a current or temperature is transformed into a voltage value in turn conforming to a dynamic range necessary to enable the microcontroller to perform a measurement accurately.

[0107] The power regulator circuit (13) thus allows to control the power transferred to the contents of the vessel in every instant and to continuously vary the desired temperature value so as to accurately follow the preset temperature/time thermal profile.

[0108] As far as energy is concerned, this type of modulation applies an average voltage to the heating elements which is lower than, equal to, or higher than the direct battery voltage, thus allowing to modulate the transferred power.

[0109] Simultaneously the microcontroller (11) controls the amount of energy drained by the accumulator (3) and the status thereof, via the energy accumulator (3) management circuit (12).

[0110] The measurement conditioning circuit (14) uses the analog/digital converter in the microcontroller (11) to transform a temperature sensor (4) resistance measurement into a very accurate digital temperature measurement.

[0111] The identifying resistor (5) readout circuit operates thanks to the fact that the microcontroller (11) sends a known, small intensity current to an identifying resistor (5) and assesses the voltage across the latter so that, a unique identifying resistor being associated with every type of container, the electronic power and control module (1) is capable of uniquely identifying the container that it has been connected to and determining the power necessary for heating.

[0112] The identification of the identifying resistor (5) mounted in the container also takes place via the analog/digital converter in the microcontroller (11); as a matter of fact, the resistance value of the resistor (5) is read via a resistive divider.

[0113] The connection control circuit is integrated in the measurement conditioning circuit (14) and takes advantage of the heating groups (2) impedance measurement to evaluate a correct interconnection between the different component parts of the container and their good operation, thanks to the analogue/digital converter in the microcontroller.

[0114] The connection control circuit can also assess, through an impedance measurement of the heating elements, for instance, a too high impedance, i.e. an open circuit, a circumstance that might mean a wrong connection between the individual components or a heating element being broken; should an impedance measurement give a too low value, i.e. a shorted circuit, it might mean, for instance, that a heating element is shorted.

[0115] Impedance measurement might also be taken advantage of for getting information on the container that the power element has been coupled with, especially if no memory elements are installed therein. As a matter of fact, lengths and shapes of the heating elements are implemented with different impedance values, as a function of the geometry and volumes of the container. Therefore, within certain intervals, the impedance value can be used to determine the type of the container, as shown for example in the following table, and to get rough information on the rower level to use.

TABLE-US-00001 Container Resistance Max power 300 ml 12.5 ohms < R < 13.5 ohms 30 W 500 ml 15 ohms < R < 18 ohms 50 W 750 ml 20 ohms < R < 22 ohms 75 W

[0116] The temperature sensor might also detect abnormalities, upon making a measurement, should the measured values be too high or too low.

[0117] In a particularly advantageous construction, the EEPROM memory (6) readout circuit (17) can be connected to the microcontroller via a connection that uses one communication wire only, according to the so-called 1 wire technology. The microcontroller might also put data stored in its own memory element available to a user via applications for portable processors, smartphones, and the like.

[0118] The user interface (8) management circuit can be integrated in the user interface or in the microcontroller (11), which is thus in a position to control a panel equipped with an LCD graphical display and/or signalling LEDs and/or buttons for accepting controls entered by a user.

[0119] If necessary, the power and control module also possibly comprises an accelerometer (7), i.e. a sensor capable of taking a measurement of displacements and their respective accelerations. This type of sensor might be extremely worth for understand whether a container is stirred or not during a heating step, so as to improve heat distribution inside the contained food, especially when this is a liquid one.

[0120] The measurement conditioning circuit (14) also allows to pick-up the acceleration signals coming from the analog outputs of the accelerometer (7), conditioning them in a range from 0 to 3 V of the analog/digital converter present in the microcontroller (11), thus making it possible to measure accelerations along the three Cartesian axes X, Y, Z.

[0121] Two solutions were worked out in embodying the invention, the former consisting of coupling the power device directly on the walls of the container, whereas in the other solution coupling takes place through the lid.

[0122] In the latter case, the lid also performs the function of interconnecting the different electric and electronic parts: heating elements, sensors, and electronic power module, besides performing the function of sealing the contents. In order to enable the lid to also perform the function of interconnecting the different electric parts, sliding connectors are used which allow to perform the electric connections between the lid and the container so that the jar can be opened and subsequently closed again. A characteristic of these connectors is in that they can handle the high currents necessary for the subject application.

[0123] The power circuit (13) contained in the power module which controls the power supplied to the heating elements (2) is connected to the lid and from this to the heating elements via slots which engage projecting pivots; besides providing an optimum electrical connection, capable of carrying currents of some Amperes, this type of connection also provides a strong mechanical connection, as necessary between the individual component parts for the heating function; slots and pivots are preferably made from metal materials.

[0124] The connection of the sensors is made via a small-piston connector. Both these couplings are of a reversible type and allow to use the electronic power module several times and on several jars.

[0125] The electronic control circuit (1) optionally allows to also install a Bluetooth controller (19), which allows to transfer all information of the power module to an ad hoc application via a smartphone or a computer.