JP2010218863A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating cooker safe and with superb thermal response capable of precisely detecting temperature of the bottom face of an actual cooking utensil. <P>SOLUTION: The induction heating cooker contains a control part 15 controlling an output of an inverter circuit 8 based on an output of an infrared sensor 4. The control part 15 selects and decides on an optimum heating power from a temperature difference between a detected temperature of the infrared sensor 4 and a target temperature as well as a temperature gradient, and carries out heating power correction from preset heating power, a material of the cooking utensil, and a temperature gradient of detected temperatures of the infrared sensor 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an induction heating cooker that heats an object to be heated such as a cooking container.

  In recent years, induction heating cookers that induction-heat cooking containers such as pans and frying pans with a heating coil have been widely used in general households and commercial kitchens.

  Conventionally, this type of induction heating cooker has a thermal element such as a thermistor provided on the lower surface of the top plate, detects the temperature of the bottom surface of the cooking container with the thermal element, and heats the detected temperature to match the target temperature. The coil is controlled.

The temperature rise at the bottom of the cooking container is moderate when a large amount of oil or food is in the pan (when the load is large) as in fried food cooking, but when only a small amount of oil is put into the frying pan (load) Is small). On the other hand, the thermosensitive element detects the temperature of the bottom surface of the cooking container placed on the top plate by detecting the heat conducted from the cooking container to the top plate. Followability is not good. Therefore, when the temperature of the bottom surface of the cooking container rises rapidly, an error between the actual temperature of the bottom surface of the cooking container and the temperature detected by the thermal element increases. As a result, even if the actual temperature of the bottom surface of the cooking container reaches the target temperature, this cannot be detected and heating is continued, and the temperature of the bottom surface of the cooking container far exceeds the target temperature and oil ignition occurs. In some cases, dangerous temperatures such as temperature were reached. Therefore, in the conventional induction heating cooker, by detecting the temperature gradient of the bottom surface of the cooking container, when the temperature gradient is steeper than the predetermined temperature gradient, by stopping the heating, Some control the heating coil so that the temperature does not reach a dangerous temperature (see, for example, Patent Document 1).
JP-A 64-33881

  However, in the conventional configuration, in the conventional induction heating cooker that controls the stop of heating based on the temperature gradient calculated based on the detected temperature of the thermal element, when the load is small, for example, cooking with a small amount of oil is performed. When cooking fried food to start, there was a case where the stop of heating was delayed as described below.

  Since the thermosensitive element detects the temperature of the bottom surface of the cooking container by detecting the temperature of the bottom surface of the top plate, the gap between the bottom surface of the cooking container and the top plate at the position where the temperature is detected by the thermosensitive element is large. And greatly affects the relationship between the detected temperature and the actual bottom temperature of the cooking container. In particular, when the pan bottom is warped, a large gap is formed between the pan bottom and the top plate. In this case, since the temperature at the bottom of the pan is not easily transmitted to the top plate, the temperature gradient calculated based on the temperature detected by the thermal element is gentler than the actual temperature gradient at the bottom of the pan. For this reason, there was a case where the heating stop was delayed.

  Moreover, when the thickness of the bottom surface of the cooking container is thin, the bottom surface temperature of the cooking container rapidly increases. On the other hand, it takes time for heat to be transferred from the bottom surface of the cooking container to the bottom surface of the top plate. Therefore, even if the same inclination as the temperature gradient of the bottom surface of the actual cooking container can be detected, there is a case where a time delay occurs until the detection is made, and the stop of heating may be delayed.

Thus, since the conventional induction heating cooker controls the stop of heating based on the temperature gradient calculated based on the detected temperature of the thermosensitive element, the stop of heating may be delayed. If the stoppage of heating is delayed, there arises a problem that the temperature of the bottom surface of the cooking container far exceeds the target temperature, and thereafter it takes a long time to stabilize at the target temperature. On the other hand, when the load is small, in order for the conventional induction heating cooker to prevent the temperature of the bottom surface of the cooking container from exceeding the target temperature, heating must be started with low heating power.

  Therefore, the conventional induction heating cooker controls the stop of heating based on the temperature gradient calculated based on the temperature detected by the thermosensitive element when the load is small, for example, when fried food cooking is started with a small amount of oil. Therefore, there was a problem that the stop of heating was delayed, and overheating or ignition could occur.

  The present invention solves the above-mentioned conventional problems, and it is an induction heating cooker that does not affect the warp or thickness of a cooking container, regardless of the load, and that controls the temperature of an appropriate cooking container with high heating power. The purpose is to provide. Specifically, it aims at optimally preventing ignition of the cooking container while realizing high-heat cooking such as stir-fried food.

  In order to solve the above-described conventional problems, the induction heating cooker of the present invention is placed on the top plate by being supplied with a top plate formed of a material that transmits infrared rays and a high-frequency current. A heating coil for inductively heating the cooking vessel; an inverter circuit for supplying a high frequency current to the heating coil; an operation unit for setting an operation mode of the inverter circuit; A storage circuit for heating and storing a control temperature corresponding to the heating power set by the operation unit, current measuring means for measuring an input current from a commercial power source and the heating coil current, and a bottom surface of the cooking vessel. An infrared sensor for detecting infrared light transmitted through the top plate; and an output of the inverter circuit is controlled based on an output of the infrared sensor. The detection signal has a size and an increase rate as the temperature of the cooking container increases in the vicinity of a control temperature range in which the temperature of the cooking container is controlled by the control unit. First temperature control means for controlling the heating power amount of the cooking container by controlling the high-frequency current of the heating coil based on the output of the infrared sensor, and the detection value of the infrared sensor is the storage circuit When the control temperature stored in the memory circuit is exceeded, the output of the inverter circuit is stopped or reduced, and when the temperature detected by the infrared sensor becomes equal to or lower than the control temperature stored in the memory circuit, the inverter circuit Temperature difference calculating means for calculating a temperature difference between a second temperature control means for increasing the output of the target temperature, a target temperature updated every predetermined time, and the infrared A temperature gradient calculating means for calculating a time change amount of a detected value of the temperature detected by the sensor; a calculated value storing means for storing a calculated value of the temperature gradient calculating means; a temperature difference calculating means; and a temperature gradient calculating means. Detecting the temperature of the bottom surface of the cooking container using an infrared sensor by performing temperature control with third temperature control means using thermal power determining means for determining the thermal power of the inverter circuit with the calculated value as input Thus, the temperature of the bottom surface of the actual cooking container can be accurately detected with good thermal response.

  The induction heating cooker of the present invention can accurately detect the temperature of the bottom surface of the actual cooking container with good thermal response by detecting the temperature of the bottom surface of the cooking container using an infrared sensor.

According to a first aspect of the present invention, there is provided a top plate formed of a material that transmits infrared rays, a heating coil that induction-heats a cooking vessel placed on the top plate by being supplied with a high-frequency current, and the heating coil An inverter circuit for supplying a high-frequency current to the operation circuit, an operation unit for setting an operation mode of the inverter circuit, and heating the cooking container when heating is started from the operation unit, according to the heating power set in the operation unit A storage circuit for storing a control temperature; current measuring means for measuring an input current from a commercial power supply and the heating coil current; and an infrared sensor for detecting an infrared ray radiated from a bottom surface of the cooking vessel and transmitted through the top plate. And a control unit that controls the output of the inverter circuit based on the output of the infrared sensor, and the infrared sensor includes the control unit The detection signal increases in size and rate of increase as the temperature of the cooking container increases in the vicinity of the control temperature range where the temperature control of the cooking container is more performed, and the heating is performed based on the output of the infrared sensor. A first temperature control means for controlling a heating electric energy of the cooking container by controlling a high-frequency current of the coil; and the inverter when a detection value of the infrared sensor exceeds a control temperature stored in the storage circuit Second temperature control for controlling the output of the inverter circuit to be increased when the output of the circuit is stopped or reduced and the temperature detected by the infrared sensor is equal to or lower than the control temperature stored in the storage circuit Means, a temperature difference calculating means for calculating a temperature difference between the target temperature updated every predetermined time, and a time change amount of a detected value of the temperature detected by the infrared sensor. A temperature gradient calculating means to be output; a calculated value storing means for storing a calculated value of the temperature gradient calculating means; and a calculated value of the temperature difference calculating means and the temperature gradient calculating means as inputs to determine the heating power of the inverter circuit. Temperature control is performed by providing third temperature control means using thermal power determining means. This makes it possible to accurately detect the temperature of the bottom surface of the actual cooking container with good thermal response.

  In the second aspect of the invention, in particular, the third temperature control means of the first aspect of the invention can perform appropriate temperature control safely by correcting according to the set thermal power from the operation unit.

  In particular, the third invention determines the material of the cooking container from the current measuring means of the first or second invention, and corrects the third temperature control means by the material of the cooking container, so that it does not depend on the cooking container. Appropriate temperature control can be performed safely.

  According to a fourth aspect of the present invention, in particular, in the induction heating cooker of any one of the first to third aspects, when the calculated value of the temperature gradient calculating means exceeds a predetermined value within a predetermined time after the start of heating, By correcting the temperature control means, it is possible to prevent overheating or ignition against a rapid temperature rise when cooking with a small amount of oil in a cooking container having a thin bottom thickness.

  In particular, the fifth aspect of the invention includes an input power integration unit that integrates input power in the control unit of any one of the first to fourth aspects of the invention, wherein the input power integration unit is provided with a predetermined integration value, and the predetermined integration value is provided. If it exceeds, the third temperature control means is not performed, so that it is possible to improve the usability when cooking with high heating power is desired.

  In the sixth aspect of the invention, in particular, when the calculated value of the temperature gradient calculating means larger than the stored value of the temperature gradient storing means of the fifth invention is detected, the third temperature control means is returned to Safety against sudden changes in temperature rise can be increased.

  In the seventh invention, in particular, the infrared sensor according to any one of the first to sixth inventions can be controlled in a fine temperature range with a wide detectable temperature range by including an InGaAs photodiode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
The induction heating cooker of the present embodiment can perform cooking with the optimum heating power safely regardless of the material and shape of the cooking container when heating with a high heating power such as stir-fried food, and is thermally responsive. By using an output signal corresponding to the temperature of the cooking container 2 by the good infrared sensor 4, optimal control during heating is performed. This induction heating cooker is used by being incorporated in a cabinet such as a kitchen, for example.

  FIG. 1 is a block diagram showing the configuration of the induction heating cooker according to the first embodiment of the present invention.

  In FIG. 1, an induction heating cooker includes a top plate 1 provided on the upper surface of a device, and a heating coil 3 (an outer coil 3a and an inner coil) for induction heating a cooking vessel 2 on the top plate 1 by generating a high frequency magnetic field. A coil 3b). The top plate 1 is made of an electrical insulator such as glass and transmits infrared rays. The heating coil 3 is provided below the top plate 1. The heating coil 3 is divided into two concentric circles to form an outer coil 3a and an inner coil 3b. A gap is provided between the outer coil 3a and the inner coil 3b. The cooking vessel 2 generates heat due to the eddy current generated by the high frequency magnetic field of the heating coil 3.

  On the user side of the top plate 1, an operation unit 14 is provided for the user to instruct the start / stop of heating. In addition, a display unit (not shown) is provided between the operation unit 14 and the cooking container 2.

  The infrared sensor 4 is provided below the gap between the outer coil 3a and the inner coil 3b. At this position, since the high-frequency magnetic field of the heating coil 3 is strong, the substantially maximum temperature of the bottom surface of the cooking vessel 2 can be detected. Infrared radiation based on the bottom surface temperature of the cooking container 2 radiated from the bottom surface of the cooking container 2 enters through the top plate 1, passes through the gap between the outer coil 3 a and the inner coil 3 b, and is transmitted by the infrared sensor 4. Received light. The infrared sensor 4 detects received infrared rays and outputs an infrared detection signal 5 based on the detected amount of infrared rays.

  Below the heating coil 3, a rectifying / smoothing unit 7 that converts an AC voltage supplied from the commercial power source 6 into a DC voltage, and a DC voltage supplied from the rectifying / smoothing unit 7 to generate a high-frequency current, the generated high-frequency current is generated. Is provided to the heating coil 3. An input current detection unit 9 for detecting an input current flowing from the commercial power supply 6 to the rectifying / smoothing unit 7 is provided between the commercial power supply 6 and the rectifying / smoothing unit 7.

  The rectifying / smoothing unit 7 includes a full-wave rectifier 10 composed of a bridge diode, and a low-pass filter composed of a choke coil 16 and a smoothing capacitor 17 connected between output terminals of the full-wave rectifier 10. The inverter circuit 8 includes a switching element 11 (IGBT in the present embodiment), a diode 12 connected in antiparallel with the switching element 11, and a resonance capacitor 13 connected in parallel with the heating coil 3. When the switching element 11 of the inverter circuit 8 is turned on / off, a high frequency current is generated. The inverter circuit 8 and the heating coil 3 constitute a high frequency inverter.

  The induction heating cooker of the present embodiment further includes a control unit 15 that controls the high-frequency current supplied from the inverter circuit 8 to the heating coil 3 by controlling on / off of the switching element 11 of the inverter circuit 8. Have. The control unit 15 controls on / off of the switching element 11 based on the signal transmitted from the operation unit 14 and the temperature detected by the infrared sensor 4.

The control unit 15 controls the high-frequency current of the heating coil 3 based on the output of the infrared sensor to control the heating power amount of the cooking vessel 2 and the detection value of the infrared sensor 4 is a storage circuit. When the stored control temperature is exceeded, the output of the inverter circuit 8 is stopped or reduced, and when the temperature detected by the infrared sensor 4 is less than or equal to the control temperature stored in the storage circuit, the output of the inverter circuit 8 Change of the detected value of the temperature detected by the infrared sensor 4, second temperature control means for controlling to increase the temperature, temperature difference calculating means for calculating the temperature difference between the target temperatures updated every predetermined time, Temperature gradient calculating means for calculating the amount, calculated value storage means for storing the calculated value of the temperature gradient calculating means, and the thermal power of the inverter circuit 8 with the calculated values of the temperature difference calculating means and the temperature gradient calculating means as inputs. Third temperature control means using a thermal determining means determining, also includes an input power integration unit for integrating the input power (not shown).

  The operation unit 14 is provided on the front side (user side) of the display unit. The operation unit 14 includes a plurality of capacitance type switches 14a to 14d. The switches 14a to 14d are switches for inputting instructions regarding cooking, and are provided corresponding to the number of heating units.

  Specific functions are assigned to the respective switches 14a to 14d. For example, the switch 14a is a turn-on / off switch to which a function for controlling the start and end of cooking is assigned.

  The switch 14d is a menu switch to which a function for switching to an operation mode suitable for the cooking menu of “heating”, “preheating heating”, “fried food”, “water heater”, and “rice cooking” is assigned. By depressing the menu switch 14d, characters and illustrations blink like “heating”, “preheating heating”, “fried food”, “water heater”, “rice cooking”, and the selection of the operation mode is switched. When the operation mode of “heating”, “preheating heating”, “fried food”, “water heater”, “rice cooking” is selected, and the switch 14a is operated, the selected operation mode is determined and determined. The display corresponding to the selected operation mode is turned on, and the display corresponding to the operation mode that has not been determined is turned off.

  The switch 14b is a thermal power setting switch to which a function for increasing the thermal power is assigned. The switch 14c is a thermal power setting switch to which a function for reducing the thermal power is assigned. When the “heating” mode is set, the heating power can be set by the heating power setting switches 14b and 14c.

  When detecting that the switches 14 a to 14 d are pressed, the control unit 15 controls the inverter circuit 8 based on the pressed switches to control the high-frequency current supplied to the heating coil 3.

  FIG. 2 shows a circuit diagram of the infrared sensor 4. The infrared sensor 4 includes a photodiode 21, an operational amplifier 22, and resistors 23 and 24. One ends of the resistors 23 and 24 are connected to the photodiode 21, and the other ends are connected to the output terminal and the inverting output terminal of the operational amplifier 22, respectively. A current flows when the photodiode 21 is irradiated with infrared rays having a wavelength of about 3 microns or less that are transmitted through the top plate 1. The higher the temperature of the irradiated infrared rays, the larger the magnitude and rate of increase of the flowing current. A light receiving element formed of InGaAs or the like. The current generated by the photodiode 21 is amplified by the operational amplifier 22 and output to the control unit 15 as an infrared detection signal 25 (corresponding to the voltage value V) indicating the temperature of the cooking vessel 2. The infrared sensor 4 receives infrared rays radiated from the cooking container 2 and therefore has better thermal response than a thermistor that detects the temperature via the top plate 1.

FIG. 3 shows the output characteristics of the infrared sensor 3 of the present embodiment. In FIG. 3, the horizontal axis represents the bottom surface temperature of the cooking container 2 such as a cooking container, and the vertical axis represents the voltage value of the infrared detection signal 25 output from the infrared sensor 4. When an infrared ray having a wavelength of about 3 microns or less that passes through the top plate 1 is irradiated, current flows. The higher the temperature of the irradiated infrared ray, the larger the magnitude and rate of increase of the flowing current. Therefore, for example, when 140 ° C. to 200 ° C. is defined as a low temperature range, 200 ° C. to 250 ° C. is defined as a medium temperature range, and 250 to 330 ° C. is defined as a high temperature range, the temperature (detection value) of the irradiated infrared rays As the value increases, the amplification factor is switched, and the temperature region is switched from a low temperature region to a medium temperature region to a high temperature region.

  In the present embodiment, when cooking is necessary for high heating power such as stir-fried food, depending on the material and shape of the cooking container, it is heated with the optimum heating power for those that affect overheating of the cooking container or oil ignition. Therefore, if the bottom thickness of the cooking container is thin (for example, 1 mm or less) when the target temperature during heating is high, the heating power is corrected so as not to overheat, and a general cooking container In (for example, a frying pan having a bottom thickness of 2.5 mm or more), it is only necessary to obtain a high thermal power output. Therefore, the infrared sensor 4 of the present embodiment outputs the infrared detection signal 25a when the bottom surface temperature of the cooking container 2 is about 140 to 200 ° C., and the infrared detection signal 25b when the bottom surface temperature is about 200 to 250 ° C. And the infrared detection signal 25c is output when the bottom surface temperature is about 250 to 330 ° C. The infrared sensor 4 does not output the infrared detection signal 25 when the bottom surface temperature of the cooking container 2 is less than about 140 ° C. “Do not output the infrared detection signal 25” in this case means not only outputting the infrared detection signal 25 but also not substantially outputting it, that is, the control unit 15 is based on a change in the magnitude of the infrared detection signal 25. And outputting a weak signal that cannot substantially read the temperature change of the bottom surface of the cooking container 2. The output value of the infrared detection signal 25 increases exponentially when the temperature of the cooking vessel 2 reaches about 140 ° C. or higher.

  About the induction heating cooking appliance comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  FIG. 4 is a diagram showing a change in the detected value of the temperature detection means and the thermal power over time when, for example, a small amount of food is put in the cooking container 2 and heated. In FIG. 4, the target temperature is Mt. A value obtained by adding a predetermined temperature Temp1 to the detection value of the infrared sensor 4 at that time is set every predetermined time ta. The maximum value of the target temperature Mt is the control temperature FMt. When heating is started, a target temperature Mt1 (not shown) obtained by adding Temp1 to the detection value of the infrared sensor 4 is set. When the target temperature Mt1 is reached, a target temperature Mt2 (not shown) to which Temp2 is added is set, and updated to the control temperature Temp2 every ta time. The temperature difference calculating means calculates a temperature difference between Mt and the detection value of the infrared sensor 4. On the other hand, the temperature gradient calculating means calculates a temperature gradient every predetermined Δt time (for example, a temperature difference of 5 seconds of the detection value of the infrared sensor 4). A temperature gradient calculating means, a calculated value storing means for storing the calculated values of the temperature gradient calculating means, and a thermal power determining means for determining the thermal power of the inverter circuit 8 from the results of the calculated values of the temperature difference calculating means and the temperature gradient calculating means. The thermal power is determined and the thermal power is updated by the third temperature control means used. As shown in FIG. 4, the thermal power is controlled while decreasing the thermal power as the temperature approaches the target temperature. The thermal power determination method of the thermal power determination means may be fuzzy control.

  The infrared sensor 4 has a characteristic of responding instantaneously by directly receiving infrared rays radiated from the bottom surface of the cooking container 2, and therefore linearly follows the temperature at which the actual cooking container is heated. Therefore, it is possible to start heating with high thermal power regardless of the shape of the cooking container.

  In addition, by setting thermal power from the operation unit, for example, when the heating power is started from low thermal power, the thermal power determined by the thermal power determining means is determined to be too low when heating the target temperature Mt, so that the thermal power is not lowered too much. At the start of heating from thermal power, if the temperature gradient after the start of heating exceeds a predetermined value (predetermined temperature) within a predetermined time, thermal power correction is applied as determined thermal power-1.

Moreover, the material of the cooking vessel 2 is determined by detecting the current characteristics flowing through the heating coil from the current measuring means, and the third material is determined by the material of the cooking vessel 2 (for example, aluminum, iron, stainless steel (magnetic, nonmagnetic)). The thermal power determining means in the temperature control means is corrected as thermal power +1 to thermal power -1.

  Further, when the calculated value of the temperature gradient calculating means exceeds a predetermined value within a predetermined time after the start of heating, the third temperature control means is corrected to a heating power −1 or a heating power −2 or less.

Further, the control unit 15 includes an input power integration unit (not shown) that integrates the input power, so that a predetermined integrated value is provided in the input power integration unit, and third temperature control means is performed when the integrated predetermined value is exceeded. For example, when cooking fried food in a frying pan, etc., load is applied and the load is applied (since the infrared sensor 4 linearly follows the temperature of the bottom of the frying pan to detect temperature instantaneously) The heating power determination means selects a higher temperature than the temperature of the bottom of the frying pan, so that the integrated predetermined value is reached, and the correction by the heating power determination means is canceled by assuming that the load is applied, and the heating power is not lowered carelessly Like that.
Further, when the calculated value of the temperature gradient calculating means larger than the stored value of the temperature gradient storing means is detected, the third temperature control means is returned.

  As described above, since the induction heating cooker according to the present embodiment detects the temperature of the cooking container 2 by the infrared sensor 4 having good thermal responsiveness, the actual temperature of the cooking container 2 is accurately detected. be able to. For example, even when the bottom surface of the cooking container 2 is warped or the bottom surface of the cooking container is thin, the actual temperature of the cooking container 2 can be accurately detected without causing a time delay. Can do. Therefore, even if heating is started at a high heating power (for example, 3 kW), the temperature of the cooking container 2 does not greatly exceed the target temperature, and the infrared sensor 4 immediately indicates that the temperature of the cooking container 2 has reached the target temperature. Can be detected. Therefore, heating can be started with high heating power. Therefore, the target temperature is reached in a short time. Therefore, it can be performed safely and accurately even when cooking stir-fried food that starts cooking with a small amount of oil and high heating power.

  In this configuration, the infrared rays emitted from the bottom surface of the cooking container 2 are directly received, and there is a characteristic that responds instantaneously, so the actual cooking container follows linearly with respect to the heated temperature. High heating power can be started regardless of the shape of the cooking container.

  In addition, by setting thermal power from the operation unit, for example, when the heating power is started from low thermal power, the thermal power determined by the thermal power determining means is determined to be too low when heating the target temperature Mt, so that the thermal power is not lowered too much. At the start of heating from thermal power, if the temperature gradient after the start of heating exceeds a predetermined value (predetermined temperature) within a predetermined time, by applying a thermal power correction as determined thermal power -1, a small amount of oil cooking, Even in a cooking container with a thin bottom, appropriate temperature control can be performed safely.

  Moreover, the material of the cooking vessel 2 is determined by detecting the current characteristics flowing through the heating coil from the current measuring means, and the third material is determined by the material of the cooking vessel 2 (for example, aluminum, iron, stainless steel (magnetic, nonmagnetic)). By correcting the thermal power determining means in the temperature control means to thermal power +1 or thermal power −1, appropriate temperature control can be performed safely regardless of the cooking container 2.

  Further, if the calculated value of the temperature gradient calculating means exceeds a predetermined value within a predetermined time after the start of heating, the third temperature control means is corrected to a heating power of −1 or a heating power of −2 or less, so that the thin bottom It is possible to prevent overheating or ignition against a rapid temperature rise when cooking with a small amount of oil in a thick cooking container.

Also, if the integrated predetermined value is exceeded, the third temperature control means is not performed. For example, when cooking fried food with a frying pan or the like, a load is applied and (the infrared sensor 4 is adjusted to the temperature of the bottom of the frying pan). In contrast, since the temperature detection is instantaneously performed following linearity), the heating power determination means selects a higher temperature with respect to the temperature at the bottom of the frying pan that has decreased with respect to the input load. Since the correction by the thermal power determining means is canceled and the thermal power is not lowered inadvertently, it is possible to improve the usability when cooking with high thermal power is desired.

  In addition, when the calculated value of the temperature gradient calculating means larger than the stored value of the temperature gradient storing means is detected, the third temperature control means is returned to be safe against sudden changes in the temperature rise of the cooking container bottom. Can increase the sex.

  In addition, since an InGaAs photodiode is used as the light receiving element of the infrared sensor 4, the temperature range that can be detected is wide and can be controlled in a fine temperature range.

  The induction heating cooker of the present invention is less affected by the warping and thickness of the cooking container, and is effective for induction heating cooking appliances used in ordinary homes and restaurants where cooking of stir-fried food is performed safely with high heating power.

The block diagram of the induction heating cooking appliance in Embodiment 1 of this invention The circuit diagram of the infrared sensor of the induction heating cooking appliance in Embodiment 1 of this invention The characteristic figure of the infrared sensor of the induction heating cooking appliance in Embodiment 1 of this invention The related figure of the detection temperature of the infrared sensor of the induction heating cooking appliance and input power in Embodiment 1 of this invention Configuration diagram of a conventional induction heating cooker

DESCRIPTION OF SYMBOLS 1 Top plate 2 Cooking container 3 Heating coil 3a Outer coil 3b Inner coil 4 Infrared sensor 4a-4f switch 6 Commercial power supply 7 Rectification smoothing part 8 Inverter circuit 10 Full wave rectifier 11 Switching element 12 Diode 13 Resonance capacitor 14 Operation part 15 Control part 16 Choke coil 17 Smoothing capacitor 21 Photo diode 22 Operational amplifier

Claims (7)

A top plate formed of a material that transmits infrared rays, a heating coil that induction-heats a cooking vessel placed on the top plate by being supplied with a high-frequency current, and a high-frequency current that is supplied to the heating coil An inverter circuit, an operation unit for setting an operation mode of the inverter circuit, and a memory that stores the control temperature corresponding to the heating power set in the operation unit by heating the cooking container when heating is started from the operation unit A circuit, current measuring means for measuring an input current from a commercial power source and the heating coil current, an infrared sensor for detecting infrared radiation radiated from the bottom surface of the cooking vessel and transmitted through the top plate, and the infrared sensor A controller that controls an output of the inverter circuit based on an output; and the infrared sensor is configured to cook the cooking by the controller. As the temperature of the cooking container increases near the control temperature range in which the temperature of the cooking chamber is controlled, the detection signal increases in size and increase rate, and the high frequency of the heating coil is output based on the output of the infrared sensor. A first temperature control means for controlling the amount of heating power of the cooking container by controlling the current; and an output of the inverter circuit when the detected value of the infrared sensor exceeds the control temperature stored in the storage circuit. Second temperature control means for controlling to increase the output of the inverter circuit when the temperature detected by the infrared sensor is equal to or lower than the control temperature stored in the storage circuit, Temperature difference calculating means for calculating a temperature difference with a target temperature updated every predetermined time, and a temperature gradient for calculating a time change amount of a detected value of the temperature detected by the infrared sensor. Calculating means; calculated value storage means for storing the calculated value of the temperature gradient calculating means; and thermal power determining means for determining the thermal power of the inverter circuit with the calculated values of the temperature difference calculating means and the temperature gradient calculating means as inputs. An induction heating cooker comprising the third temperature control means used to perform temperature control. The induction heating cooker according to claim 1, wherein the third temperature control means corrects according to a set heating power from the operation unit. The induction heating cooker according to claim 1 or 2, wherein a material of the cooking container is determined from the current measuring means, and the third temperature control means is corrected by the material of the cooking container. The induction heating cooker according to any one of claims 1 to 3, wherein when the calculated value of the temperature gradient calculating means exceeds a predetermined value within a predetermined time after the start of heating, the third temperature control means is corrected. . 5. The control unit according to claim 1, further comprising an input power integration unit that integrates input power, providing a predetermined integration value in the input power integration unit, and not performing the third temperature control unit when the integration predetermined value is exceeded. The induction heating cooking appliance of any one of Claims. The induction heating cooker according to claim 5, wherein when the calculated value of the temperature gradient calculating means larger than the stored value of the temperature gradient storing means is detected, the third temperature control means is returned. The induction heating cooker according to any one of claims 1 to 6, wherein the infrared sensor includes an InGaAs photodiode.