Temperature measurement in a cooking vessel

The invention relates to a method of transmitting a sensor data associated with an inductively heated cooking utensil, to a reading device, a sensor device for an induction heating cookware, a cooking utensil, an induction heating device and a system. [0002] In order to accurately control or regulate the cooking process, it is necessary to detect the temperature of the cooked product as accurately as possible. [0003] DE 10 2009 047 185 A1 describes a method and a device that allows determining by determining the specific parameters of the bottom temperature of the vessel for cooking, heated by means of an induction heating coil. The effects depend on the cooked product, especially when preparing foodstuffs containing starch and protein, however, they make it difficult to determine the temperature of the cooked product unambiguously depending on the temperature of the bottom of the cooking utensil, [0004] It may be necessary to predict a sensor dedicated to measure the temperature of the cooked product. The temperature data, or sensor data, must then be transferred in a suitable manner to the reading device, which then evaluates them, for example automatically controls the cooking process taking into account the temperature of the cooked product.

[0005] DE 10 2008 054 906 A1 discloses a method and apparatus for which data is transferred wirelessly between an attachment device and a consumable device.

The object underlying the invention is to provide a method for transmitting a sensor data which is assigned to an induction heating cookware, to a reading device, a sensor device for an induction heating cookware, cooking utensils, an induction heating device and a system that they enable reliable and inexpensive implementation of sensor data transfer.

The invention solves this task by a method according to claim 1, a cookware according to claim 10, an induction heating device according to claim 12 and a system according to claim 13. Preferred embodiments are subject of the dependent claims, the content of which therefore constitutes by including the content of the description.

[0008] In the case of a method for transmitting a sensor data to a reading device, wherein the sensor is associated with an inductively heated cooking utensil, for example inside a cooking utensil to detect the temperature of the cooked product that is in the cooking pot, conventionally by means of an inverter from an AC voltage, a high frequency control voltage, wherein the oscillating circuit with an induction heating coil is fed with a high frequency control voltage to produce a high frequency magnetic field for heating the cooking utensil. The control voltage frequency may be, for example, in the range between 20 kHz and 50 kHz.

ΕΡ 2 735 210 Β1 of an alternating network, in order to induce the own resonance oscillation of the oscillating circuit. The first time interval may be predetermined, for example, by the fact that the value of the alternating voltage of the network during the first time interval is less than a predetermined value, for example less than 25 V, especially less than 18V. During the second time interval, which is completely within the first time interval and can be identical to the first time interval, the impedance of the inductively or magnetically coupled coupling changes with the induction heating coil that is assigned to the cooking utensil or can be part of the vessel for cooking, depending on the sensor data being transferred, i.e. the load modulation is carried out. With binary data transfer, for example, the logical one can be assigned high impedance according to the value, and logically zero according to the value of low impedance or vice versa. The change in impedance changes the resonance frequency of the self-resonance oscillation. Finally, the transferred sensor data is decoded in the reading device, whereby the resonance frequency is detected and evaluated, especially the resonance frequency change, the oscillation of the oscillation circuit itself. In the development, a high frequency alternating magnetic field energizes the system contactlessly with operating energy which is made to detect the sensor data and to change the impedance inductively coupled to the induction heating coil of the antenna depending on the data being transferred.

[0010] In the development, the sensor data is temperature data of the cooked product, which is heated by means of a cooking utensil or in a cooking vessel.

[0011] In an expansion, the sensor data is transferred by means of or as part of a data telegram, the data telegram comprising at least one starting bit and / or at least one security bit.

[0012] The sensor device for the inductively heated cooking vessel has: at least one sensor for detecting a measurand, relating to a cooking utensil, especially the temperature of the cooked product, which is heated by a cooking utensil, an antenna that is inductively coupled to an induction cooker. a heating coil of an induction heating device, wherein the induction heating device generates a high frequency drive voltage for the induction heating coil by means of an inverter from the grid voltage, means for varying the antenna impedance, means for detecting the time interval within the zero crossing of the AC network voltage and the device controlmade to determine the data of at least one sensor and to control means for varying the impedance of the antenna with them in such a way that the antenna impedance varies depending on the determined data of the at least one sensor during the time interval within the zero crossing of the AC voltage.

[0013] In development, the antenna includes a coil or antenna constituting a coil.

[0014] In a development, the means for varying the antenna impedance comprises a switching means that is connected in addition to further construction elements or without further elements between the coil connections.

[0015] In a development, the means for detecting the time interval within the zero crossing of the AC voltage comprises means for measuring the antenna voltage, in particular the upright voltage.

ΕΡ 2,735 210 Β1 [0016] In an elaboration, an energy supply device is provided, which is made to generate from the signal of the operating energy for the sensor device on the antenna.

[0017] The cooking utensil according to the invention has the sensor device indicated above. [0018] In the development, the antenna, especially in the form of a single or multi-start coil, is placed on the bottom of the cooking utensil or forms the part of the cooking utensil which in use is in contact with the ceramic plate of the induction hob.

The induction heating device according to the invention has: a vibratory circuit, which includes an induction heating coil, a converter that generates a high frequency control voltage from the AC voltage, wherein the oscillating circuit is supplied with a high frequency control voltage to produce a magnetic high frequency alternating field for heating the cooking utensil, means for detecting the time interval within the zero crossover of the AC network voltage and a control device which is made to interrupt the supply of the high frequency oscillating circuit during the time interval within the zero crossing of the AC voltage network to induce or allow resonance oscillations of the vibratory circuit,for determining the resonance frequency, in particular the resonance frequency variation, the oscillation of the resonance of the oscillating circuit and for decoding the transferred data on the basis of a fixed resonance frequency, or changing the resonance frequency.

[0020] The system according to the invention is made for carrying out the above-mentioned method and has the above-mentioned sensor device and the above-mentioned induction heating device.

[0021] The invention will be described below with reference to the drawings, which show preferred embodiments. At the same time, it shows schematically:

1, a system having an induction heating cooker with a sensor device and an induction heating device, and FIG. 2 an alternating voltage waveform of the network and a first self-oscillation time interval and a second time interval during which the sensor data is transferred.

[0022] Fig. 1 shows a system with an induction heating vessel 2 which has a sensor device 12 and an induction heating device 16.

[0023] The sensor device 12 has: a temperature sensor 1 in the form of a conventional NTC temperature sensor for detecting the temperature of the cooked product which is heated by a cooking utensil 2, the sensor being positioned within the cooking vessel 2, for example within an unspecified space empty in the side walls or on the bottom of the cooking utensil 2 or on the elastic lines freely movable inside the cooking utensil 2, e.g. in the form of an internal temperature sensor, a coil antenna 6 that is inductively or magnetically coupled to the induction heating coil of the induction device heating device 16, a power supply device in the form of a rectifier, for example a bridge rectifier 11, which rectifies the output voltage of the coil 6,wherein the straightened UP voltage feeds after smoothening by the smoothing capacitor 19 the sensor device 12, or at its base

ΕΡ 2 735 210 Β1 system 7, means for varying the effective impedance of the coil 6 in the form of switching means 8, for example in the form of a transistor, with a restriction choke 18 already connected, the switching means 8 being connected between the coil connections 6, the rectifier output 11, means for detecting the time interval {see FIG. 2 & quot; ZB2 & quot;) within the zero crossing of the AC voltage of the UN network in the form of a voltage detector 9 for measuring the level of upright antenna voltage UP and a control device in the form of a microcontroller 10 that is made for conventional data acquisition sensor 1, e.g. by means of conversion A / D and controlling the switching means 8 in such a way,that the coil impedance 6 is varied depending on the sensor data determined during the ZB2 time interval within the zero crossing of the AC voltage of the UN network.

[0024] The induction heating device 16 has a vibratory circuit 15 which includes an induction heating coil 5 and capacitors 13 and 14, the capacitors 13 and 14 being connected in a conventional manner between the inter-circuit voltage UZK.

The conventional converter 4 generates, from the AC voltage of the UN network, for example by means of a half-bridge, a high frequency UA control voltage, wherein the oscillating circuit 15 is supplied with a high frequency UA control voltage to produce a magnetic high frequency alternating field for heating cooking utensils 2.

The induction heating device 16 further includes means 17 for detecting the time interval (see Fig. 2 "ZB1") within the zero crossing of the AC voltage of the UN network. The time interval ZB1 can be detected or determined, for example in that the value The voltage of the alternating UN network during the time interval ZB1 is less than a predetermined value, e.g. less than 25 V, especially less than 18 V. The means 17 supervise the AC voltage level of the UN network in this case and thus detect the time interval ZB1 within the transition through zero AC voltage on the UN network.

[0027] Furthermore, a control device in the form of a microcontroller 3 is conducted, which is made to interrupt the supply of the oscillating circuit 15 with the high frequency UA control voltage during the ZB1 time interval, to induce the resonance oscillation of the oscillating circuit 15, determining the change in the resonance frequency of the vibrations. self-resonance of the oscillating circuit 15 and decoding the data carried by the sensor device 12 based on a fixed change in the resonance frequency. The microcontroller 3, which is part of the induction heating device 16, thus fulfills the conventional functions of controlling the induction heating device and, additionally, the function of the reading device that receives and appropriately assesses the transferred data from the sensor 1. The induction heating coil 5 simultaneously serves as the receiving antenna,

[0028] The sensor device 12 can be part of the cooking utensil 2 or can be detachably connected to the cooking vessel 2, the coil 6 being provided at the bottom of the cooking utensil 2, and the remaining components can be integrated, for example with a handle not shown or empty space for cooking utensils 2, where they are protected from high temperatures. With detachable connection, sensor device 12 or part of the sensor device 12

ΕΡ 2,735 210 Β1 can be integrated, for example, with a plastic frame that is attached to a conventional cooking vessel.

[0029] Fig. 2 shows, for explanation, the course of the AC voltage of the UN network and the time interval ZB1, the resonance oscillation of its own oscillating circuit 15 and the time interval ZB2 during which the data of the sensor is transferred.

[0030] It is understood that instead of a single sensor, several sensors may also be provided, which may then be placed at different positions of the cooking utensil 2. In this case, it is possible to transfer the average value calculated by all sensors to the reading device 3, or that the data of all sensors is transferred to the reading device.

The induction heating device 16 according to the invention is also suitable for heating cooking utensils that do not have the sensor device 12 according to the invention. In this case, the inductive heating device 16 or its reading device 3 recognizes the lack of sensor data and passes through. then in a conventional operating condition without detecting the temperature of the sensor.

[0032] On the other hand, the sensor device 12 according to the invention can also be operated on a conventional induction heating device. In this case or in principle, the sensor device 12 may further comprise an acoustic generator which, when the sensor temperature is exceeded, produces an audible warning signal to prevent damage to the cooking utensil 2.

It is understood that in addition or as an alternative to temperature sensors, sensors for further measured quantities, e.g. pressure sensors for pressure cookers can also be provided.