Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
  • H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
  • H05B3/746—Protection, e.g. overheat cutoff, hot plate indicator
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/02—Induction heating
  • H05B6/06—Control, e.g. of temperature, of power
  • H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2213/00—Aspects relating both to resistive heating and to induction heating, covered by H05B3/00 and H05B6/00
  • H05B2213/05—Heating plates with pan detection means
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2213/00—Aspects relating both to resistive heating and to induction heating, covered by H05B3/00 and H05B6/00
  • H05B2213/07—Heating plates with temperature control means

Definitions

• the present invention relates to the field of cooking plates, in particular those allowing the detection of the temperature of a culinary article. From a general point of view, it is a question of determining the temperature of a culinary article so as to optimize the cooking of a food, or to protect the cooking utensil, and this independently of the size of the article .
• the invention relates to a cooking plate adapted to receive a cooking utensil and comprising a measuring system which is adapted to measure the temperature of the culinary article, and which comprises measuring means and control means.
• Such a plate is well known to those skilled in the art, in particular by the example given in the prior art document JP 5344926.
• This document describes a cooking system comprising a cooking utensil and a cooking plate. cooking.
• the culinary article is equipped with a thermosensitive means, and a secondary coil forming a closed circuit with the thermosensitive means.
• the cooking plate is provided with a primary coil, a high frequency generation means inducing a current in the secondary coil, and a temperature sensing means which determines the temperature of the cooking utensil according to the current level flowing in the primary coil.
• the culinary article comprises at its bottom a sensor cooperating with a second sensor located in or on the hob.
• the sensor of the culinary article is essentially a multilayer ceramic sensor called "binary" to detect the achievement of target temperatures by abrupt modification of the dielectric constant at target temperatures.
• the cooking plate comprises a set of sensors, or electrodes, capacitively connected to the sensor dielectric located in the bottom of the cooking utensil.
• the disadvantage of such a configuration is that it requires a particular steric arrangement for the positioning of inductive heating means and measuring means. In addition, it requires two measuring coils for a heating coil.
• the present invention aims to overcome these disadvantages by providing a simple device, easy to use and maintenance.
• the hob according to the invention is essentially characterized in that the measuring means comprise an electric circuit which has at least one element of inductive nature configured to inducing a magnetic field towards the culinary article and which transmits to the control means a signal resulting from the action of the induced magnetic field on electrically conductive thermosensitive means of the culinary article, the control means comprising at least one corresponding model the thermal behavior of the thermosensitive means, and being configured to convert the value of the transmitted signal into a temperature from the model.
• the temperature of the culinary article can be measured accurately, since the resistivity varies continuously with temperature and this is more representative of the temperature of the food since it is directly on the food. culinary article and not on the cooking plate.
• the measurement of the temperature can be performed during the heating of the culinary article by remote measuring means in the cooking plate without contact with the article. Thanks to the direct treatment by the electronics of the hob, it is not necessary to introduce this electronics (measurement, transmission ...) in a handle of the culinary article or to come to connect a probe of temperature in contact with the culinary article and the electronics of the plate.
• the regulation of the The temperature of the cooking utensil does not involve any signal transmission, in the sense that no means of infrared or radio communication is required between the cooking plate and the article.
• the temperature measurements made are discrete measurements whose frequency is advantageously periodic and can be chosen, or even modulated according to the temperature or the type of non-ferromagnetic material.
• the culinary article can be used on any conventional type of heating means (induction, radian, gas, etc.), without risk of deterioration of the heat-sensitive means.
• FIG. 1 shows a cross section of a portion of a cooking system (in operation) comprising a -culinaire article according to an embodiment of the present invention and a cooking plate, the plate heating means cooking zone being in the heating state and the measuring means being in stop mode,
• FIG. 2 is similar to FIG. 1, the heating means being in the off state and the measuring means in the induction mode, and
• a cooking system 1 for cooking food includes a cooking utensil 100 adapted to receive food or a cooking fluid (water, oil ...), for example a pan or a 5, and a cooking plate 200 adapted to support the culinary article 100 and to transmit to the latter the energy required for cooking the food it contains.
• a cooking utensil 100 adapted to receive food or a cooking fluid (water, oil ...), for example a pan or a 5, and a cooking plate 200 adapted to support the culinary article 100 and to transmit to the latter the energy required for cooking the food it contains.
• the culinary article 100 comprises a base body 150 made from a thermally conductive base material, for example aluminum.
• This basic body generally defines the geometric structure of the culinary article and can serve as a support for a possible interior and / or exterior coating (enamel, paint, Teflon coating ).
• the culinary article 100 defines a receiving volume of the food to be cooked which is delimited by a bottom 101 and a side wall 102.
• the bottom 101 of the culinary article 100 here circular in shape, has
• At least a portion of at least one one of the faces 110, 120 of the bottom 101 has a substantially planar appearance, so as to ensure the stability of the culinary article 100 when it is placed on a horizontal surface (cooking plate 200, table, etc.).
• the faces 110, 120 of the bottom 101 are entirely flat and the thickness of the bottom 101 is constant.
• the bottom 101 is formed mainly by the material of the base body 150.
• the culinary article 100 comprises heat-sensitive means 130 which conduct electricity. These heat-sensitive means are intended to enable the temperature of the culinary article 100 to be determined.
• the material chosen for the heat-sensitive means 130 has a high variability of its p-resistivity over a given temperature range (preferably from 20.degree. C at 300 ° C.), which makes it possible to obtain precise temperature measurements.
• the variation of resistivity p as a function of the temperature (in the given temperature range) is linear, and, in order to obtain a high precision in the measurement of the temperature, that the temperature coefficient C ⁇ is high.
• the heat-sensitive means 130 are non-ferromagnetic means.
• the heat-sensitive means are made of titanium.
• the heat-sensitive means 130 are integrated in the bottom 101 of the culinary article 100.
• the heat-sensitive means 130 have a constant thickness.
• the heat-sensitive means 130 are formed by a thermosensitive element 130 (an insert integrated in the base body 150).
• the heat-sensitive means 130 (here, a face of the insert 130) constitute a part of the outer wall 102 of the bottom 101 of the culinary article 100 (here the central portion), as shown in Figures 1 and 2.
• the heat-sensitive means 130 have a symmetrical shape of revolution whose axis S is perpendicular to the plane of the bottom 101.
• the insert 130 has the appearance of a disk which is concentric with the bottom 101 of the culinary article 100.
• the culinary article 100 also comprises ferromagnetic means 140.
• These ferromagnetic means 140 are intended to allow the heating of the food when the cooking plate 200 on which rests the culinary article 100 is a magnetic induction plate, and they are configured to transform an incident magnetic field (shown in Figure 1 by field lines 211) from the hotplate 200 into heat, by Joule effect (induced by eddy currents).
• the ferromagnetic means 140 are integrated "in” Ie ⁇ -Wallpaper 101 "de the culinary article 100, and more precisely in the main body 150.
• the ferromagnetic means 140 extend in a ring 140. They may be, for example, in the form of a grid or hot-glued capsules.
• the heat-sensitive means 130 and the ferromagnetic means 140 are arranged relative to each other so that the heat generated by the ferromagnetic means 140 is transmitted by thermal conduction to the heat-sensitive means 130.
• the crown 140 in ferromagnetic material is in contact with the circular insert 130 of thermosensitive material which it surrounds.
• the cooking plate 200 includes a receiving surface 201 adapted to receive the culinary article 100 (more specifically, the lower face 120 of its bottom 101).
• the cooking plate 200 comprises at least one focus (in this case, only one).
• the cooking plate 200 comprises a heating system 202 and a temperature measuring system 203.
• the heating system 202 comprises heating means 210 and regulating means 230. At each hearth are associated heating means 210 which are clean .
• the regulation means 230 for example a microcontroller and its adapted program, allow, for example, the regulation of the heating means 210 around a setpoint, or the triggering of a timer, etc.
• the heating means 210 are inductive.
• they comprise an inductor, in this case an inductive heating coil 210.
• Each focal point comprises at least one inductive heating coil 210 (in this case, only one).
• the cooking plate 200 comprises first thermal protection means which make it possible to thermally protect the heating means 210 when they are inductive.
• the heating system 202 is configured so that the heating means 210 provide a sequenced heating over time and pass successively and alternately in a heating state in which they generate and transmit the cooking energy, and in a state of stopping in which they no longer generate this energy.
• the heating means 210 being inductive, they are powered by an alternating current of frequency f x modulated in amplitude by a frequency f 3 , the zero (and the adjacent area as explained below) of the corresponding modulation in the off state and the rest in the heating state.
• a typical ⁇ ⁇ frequency is, for example, 18 to 25 kHz.
• a typical modulation frequency is f 3 equal to 50 Hz or 60 Hz (100 Hz or 120 Hz after rectification).
• the temperature measuring system 203 comprises measuring means 220 and control means 240.
• the measuring means 220 comprise an electrical circuit 219 having at least one element of inductive nature 221, regardless of the nature (inductive or not) of the heating means 210.
• the element of inductive nature is a inductor 221, in this case, an inductive measuring coil 221.
• the inductive measuring coil 221 is disposed at the center of the induct-heating coil 210. ⁇ • -. ⁇ ---
• the magnetic field (shown in FIG. 2 by field lines 222) generated by the inductive measurement coil 221 is of much smaller amplitude than that generated by the inductive measuring coil 210 and does not make it possible to heat a ferromagnetic material by induction.
• the inductive measuring coil 221 makes it possible to measure by induction the intensity of the current flowing in the thermosensitive element 130 of the culinary article 100 when it is positioned on the receiving surface 201. Indeed, the inductive measuring coil 221 is comparable to the primary circuit of a transformer while the heat-sensitive means 130 of the culinary article 100 are the secondary circuit.
• the principle of the measurement is based on the variation of the impedance Z of the electrical circuit 219 (in this case an RLC circuit comprising the measurement inductive coil 221 and a capacity capacitor C connected in series with the inductive measuring coil 221. ) as a function of the variation of the temperature of the temperature-sensitive elements 130.
• the measuring coil 221 is characterized by an inductance L B (whose variation as a function of the temperature is sufficiently low to be neglected) and a resistor R B.
• the value of the impedance Z of the electrical circuit 119 (primary circuit) is a function of the resistance R B of the inductive measuring coil 221 (whose value is known) and of the resistor R 3 of the secondary circuit formed by the heat-sensitive material 130 (whose value depends on the temperature).
• thermosensitive means 130 and therefore their resistivity p (the dimensions of these means being known) and their temperature.
• the control means 240 make it possible to determine the temperature of the culinary article 100 from the measurement of the intensity I of the current flowing in the measuring inductive coil 221, the measuring means 220 transmitting towards the control means 240 a signal of which the value is representative of the impedance Z of the circuit 119 (in this case, the intensity I of the current flowing in the inductive measuring coil 221).
• the control means 240 comprise at least the model of the thermal behavior of the resistivity p of the thermosensitive material 130 inserted into the bottom of the culinary article 100. It is easy to understand that the use of thermosensitive means 130 with a temperature coefficient C T constant (actually or according to an acceptable approximation) in the operating temperature range of the culinary article 100 makes it possible to greatly facilitate the determination of the temperature from a value of the resistivity p, the model then being linear . In order to achieve this determination, the control means 240 advantageously comprise a microprocessor.
• the inductive measuring coil 221 In order to facilitate the determination of the temperature (more precisely, in order to facilitate the correlation between the variation of the resistance R and the intensity I), it is advantageous for the inductive measuring coil 221 to be
• the capacitor C is chosen as a function of the supply frequency f 2 and the inductance L B of the inductive measurement coil 221.
• the inductive measurement coil 221 thus makes it possible to measure a variation of resistance R. who can be correlated with a temperature variation of the culinary article 100.
• ⁇ and ⁇ r vary at the same time, it is extremely difficult to connect the variation of the resistance R measured by the inductive measuring coil 221 (in fact the intensity I) to the temperature of the article.
• the heat-sensitive means 130 are non-ferromagnetic, the magnetic permeability ⁇ r then being comparable to 1 and not dependent on the temperature, unlike a ferromagnetic material.
• their thickness E is chosen as a function of the frequency f 2 of the supply voltage U of the inductive measuring coil 221. so as to be greater than the penetration depth ⁇ associated with this frequency f2.
• the frequency f 2 of the supply voltage U of the measuring inductive coil 221 can be determined as a function of the thickness E of the heat-sensitive means 130 and the desired penetration depth ⁇ .
• the means thermosensitive 130 non-ferromagnetic titanium have a thickness of 1.2 mm for a frequency f 2 of 5OkHz.
• thermosensitive means 130 a non-ferromagnetic material is that, in this case, the inductance L B (known) of the inductive measuring coil 221 varies little in its presence.
• the only variable element as a function of the temperature in the impedance Z of the circuit 119 is the resistivity p of the heat-sensitive means 130 (and therefore the sole property of the thermosensitive means 130 to intervene in the measurement of the Temperature when they are made in a non-ferromagnetic material is the variation of their resistivity p), which makes it easy to obtain an accurate measurement.
• the thermosensitive means 130 are advantageously positioned vis-à-vis the measuring inductive coil 221.
• the surface of the thermosensitive means 130 is preferably greater than that of the inductive measurement coil 221. , which increases the reliability of the measurement.
• the cooking plate 200 comprises second thermal protection means which make it possible to thermally protect the measuring means 220.
• These second thermal protection means may be either specific or constituted by the first means thermal protection.
• the heating means 210 are inductive, so as not to disturb the measurement of the temperature of the culinary article, this is preferably done around the zero crossing of the modulation of the supply current of the heating means 210, so as to avoid induction phenomena between the heating inductive means 210 and the measuring inductive means 220, even if the respective frequencies f 1 , f 2 are preferably substantially different (the frequency
• the inductive measuring coil 221 in operation, successively and alternately passes in stop mode in which it is powered by a zero voltage (circuit
• FIG. 3 represents, for the same arbitrary time unit, the evolution of the voltage across the coil inductive measurement 221 at a frequency f 2 and 0 the evolution of the modulated current in the inductive coil of
• the cooking plate 200 comprises complementary measuring means (not shown) suitable for measuring the temperature of the receiving surface 201, for example means of the CTN type (means whose electrical resistivity is a function of a Negative Temperature Coefficient).
• These complementary measuring means are connected to the temperature measurement system 203 (and more particularly to the control means 240) and make it possible to correlate the measurement made by the inductive coil of measurement 221.
• the temperature comparison may take place only at the beginning of the heating of the culinary article 100 or at the beginning of the heating of the culinary article 100 or any time during this heating.
• the detection of a temperature by the inductive measuring coil 220 and / or by the complementary measuring means also makes it possible to determine the attainment of a maximum target temperature generating a heating stop and thus protecting the culinary article 100.
• the culinary article 100 is positioned on the induction hob 200.
• the inductive heating coil 210 produces a magnetic field which induces currents in the ferromagnetic means 140 of the bottom 101 of the culinary article 100, which, by the Joule effect, heats these ferromagnetic means 140 and, by thermal conduction, the rest of the culinary article 100 , including the thermosensitive insert 130.
• the resistivity p and the resistance R s of the heat-sensitive means 130 change, as well as the resistance R and the impedance Z of the electrical circuit 119. Due to the use of a non-ferromagnetic material as a heat-sensitive medium 130 and the supply of the inductive measuring coil 221 by a voltage U whose frequency f 2 corresponds to the resonance frequency f r of the electric circuit 119, the intensity I sent by the measuring means 220 to the means of - control
• the temperature measurement system 203 allows the latter to easily determine the temperature of the culinary article 100 from this intensity I.
• the temperature measurement system 203 can also be used for other functions such as the detection of the presence of a culinary article 10 on the cooking plate 200, or even its centering, or the recognition of the type of culinary article 100 or its compatibility with the cooking plate 200, combined for example with the generation of an error signal or inhibiting the heating means.
• the presence a metal material in the vicinity of the measuring means 220 changes the impedance of the circuit 119, and this change is translated by the control means 240 without necessarily converting this impedance change temperature.
• the present invention is not limited to the present embodiment.
• the material used for producing the heat-sensitive means it is possible to use metals such as titanium, bismuth, molybdenum (in particular molybdenum silicon MoSi2), platinum, copper, aluminum, magnesium, zinc or nickel, or alloys. of these metals or metal ceramics, austenitic stainless steel or non-ferrous enamels.
• the heat-sensitive means they may have another '-forma .qu'un disc', for example forming an assembly comprising at least one ring or a sum of concentric rings with the bottom center of the cooking utensil and preferably connected thermally between them. They may have a relief or cutouts (preferably, the cuts are located in the plane of the bottom of the culinary article).
• They may also, at least in part, be covered with a material transparent to a magnetic field, such as an enamel or a paint, which forms at least part of the bottom face of the bottom of the culinary article which allows to the culinary article of power be easily cleaned without risk of deterioration of the heat-sensitive means.
• a material transparent to a magnetic field such as an enamel or a paint
• the heat-sensitive means may not form an insert, but may be deposited in the form of a layer (s), for example by screen printing or thermal spraying. They can also be formed by several superimposed non-ferromagnetic materials, for example rolled or layered.
• the ferromagnetic means may be remote from the heat-sensitive means as long as the heat-sensitive means are not thermally insulated.
• the hob could include several homes, each of which is respectively equipped with a measuring coil.
• the cooking plate may comprise only one measuring system for all the hearths, connected by multiplexing to the different measuring coils of the hearths.
• control means may comprise several models of thermal behavior
• a thermal behavior model may include several thermal behavior patterns for a plurality of measurement frequencies, which
• control means could be coupled with the control means, for example in the form of an electronic circuit, or integrated together in a microprocessor.
• the supply voltage of the measuring means can be in the form of of a multifrequency excitation, or in the form of pulse (s) of Dirac.
• N N natural integer (eg every five or ten seconds with a 50 Hz modulation) and stop the inverter during an ark (half a period) so as to have a zero current in the inductive heating coil without disturbing the heating of the article.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Cookers (AREA)
• Induction Heating Cooking Devices (AREA)
• Baking, Grill, Roasting (AREA)

Applications Claiming Priority (2)

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• 2006
  • 2006-07-06 FR FR0606175A patent/FR2903564B1/fr not_active Expired - Fee Related
• 2007
  • 2007-07-06 EP EP07803856A patent/EP2039223A2/fr not_active Withdrawn
  • 2007-07-06 CN CN2007800257131A patent/CN101485231B/zh not_active Expired - Fee Related
  • 2007-07-06 WO PCT/FR2007/001158 patent/WO2008003872A2/fr active Application Filing
  • 2007-07-06 JP JP2009517339A patent/JP5254966B2/ja not_active Expired - Fee Related
  • 2007-07-06 US US12/307,607 patent/US20090314769A1/en not_active Abandoned

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