JP2014093293A - Heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating cooker which allows for accurate determination of the gap distance between the bottom of a heated article mounted on a top plate and the surface of the top plate.SOLUTION: A heating cooker 100 includes a top plate 2 on which a heated article is mounted, heating means arranged under the top plate 2, top plate temperature detection means for detecting the temperature of the top plate 2, gap distance determination means for determining the gap distance between the bottom of a heated article mounted on the top plate 2 and the surface of the top plate 2, based on the detection results of the top plate temperature detection means, and a control unit 23 for stopping the heating of the heating means continuously until the top plate temperature lowers by a predetermined temperature, when the initial top plate temperature before the heating means starts heating is equal to or more than an initial threshold, and starting determination of the gap distance by the gap distance determination means when the top plate temperature lowers by a predetermined temperature.

Description

  The present invention relates to a heating cooker that detects the temperature of an object to be heated placed on a top plate.

  As a method of detecting the temperature of the pan, which is the object to be heated, placed on the top plate of the heating cooker, a thermistor, which is a contact-type temperature sensor, is brought into contact with the top plate and transmitted from the pan through the top plate. There are a thermistor method for detecting the temperature to be detected and an infrared sensor method for detecting the infrared radiation energy radiated from the pan through a top plate.

  In the thermistor method, the thermistor is brought into close contact with the lower surface of the top plate, and the temperature of the pan is detected by the thermistor through the top plate. For this reason, the temperature of the pan is not directly transmitted to the thermistor, and there is a problem that the followability of the temperature detection of the thermistor to the temperature change of the pan is low.

  In addition, the infrared sensor system has an infrared sensor disposed below the central space of the heating coil and the space between the inner coil and the outer coil, and the infrared radiation energy radiated from the pan placed on the top plate The temperature of the pan is detected by the amount of energy.

  Unlike the thermistor method, this infrared sensor method does not cause a follow-up problem between the temperature of the pan and the detection value of the infrared sensor, but the detection accuracy is affected by the difference in the color of the pan bottom. That is, since the emissivity from the infrared radiation surface varies depending on the color of the pan bottom, the amount of infrared radiation energy radiated from the pan may differ even if the pan temperature is the same. For this reason, even if the temperature of a pan is actually the same, there exists a problem measured as different temperature.

  Moreover, the top plate itself is also heated by the heat transfer from the heated pan. For this reason, an infrared sensor will also detect the infrared rays radiated | emitted from a top plate. Therefore, as the top plate is heated, it becomes more difficult to accurately detect the temperature of the pan to be acquired.

  Therefore, with these problems as a background, as shown in Patent Document 1, by embedding silicon in the upper part of the infrared sensor of the top plate, the portion is configured to transmit infrared rays in a wide wavelength band, and infrared rays emitted from the pan There is a cooking device in which the amount of light is received by an infrared sensor through silicon. In this cooking device, the emissivity of the pan is estimated from the rate of temperature rise of the top plate detected by the thermistor, and the estimated radiation of the pan is calculated by subtracting the amount of silicon radiation from the infrared sensor output value. Multiply the rate and set the temperature of the pan.

  Also, as shown in Patent Document 2, a correspondence relationship between the temperature of the top plate and the infrared radiation energy radiated from the top plate is obtained in advance, and the infrared radiation energy detected by the infrared sensor is used to obtain a contact-type temperature sensor. By removing the infrared radiant energy corresponding to the detected temperature of the top plate, the heating cooker that calculates the infrared radiant energy radiated from the pan, and converts this infrared radiant energy into temperature to estimate the pan temperature. is there.

Japanese Patent No. 4745012 (pages 5 to 8) JP 2011-34743 A (pages 7 and 8)

  In the heating cookers described in Patent Document 1 and Patent Document 2, the temperature of the infrared sensor and the top thermistor at the same time (Patent Document 1) and pan reflectance (Patent Document 2) Estimate the rate, subtract the amount of infrared radiant energy emitted from the top plate from the amount of infrared radiant energy output from the infrared sensor, and multiply the subtracted value by the emissivity of the pan to estimate the temperature of the pan. ing.

  However, when the pan is warped and part of the pan is floating from the top plate, there is an air layer between the top plate and the pan bottom, until the infrared rays emitted from the pan bottom reach the top plate. Attenuates. Therefore, the rate of temperature rise of the top plate differs depending on whether the pan bottom is floating from the top plate or not. For this reason, in the configurations of Patent Document 1 and Patent Document 2, it is difficult to accurately subtract the influence of the top plate from the amount of infrared radiation energy detected by the infrared sensor. Also, the rate of temperature rise of the top plate and the rate of temperature rise of the infrared sensor differ depending on the gap distance between the bottom surface of the object to be heated and the surface of the top plate, so the emissivity of the pan may be set incorrectly. There is. Thus, due to the gap distance between the bottom surface of the object to be heated and the surface of the top plate, there is a problem with the accuracy of temperature detection of the pan, and it was desired to accurately determine the gap distance. .

  The present invention has been made against the background of the above problems, and accurately determines the gap distance between the bottom surface of the object to be heated placed on the top plate and the surface of the top plate. A cooking device capable of cooking is provided.

  The cooking device according to the present invention includes a top plate on which an object to be heated is placed, a heating unit disposed under the top plate, a top plate temperature detecting unit for detecting the temperature of the top plate, and a top plate temperature. Based on the detection result of the detection means, a gap distance determination means for determining a gap distance between the bottom surface of the object to be heated placed on the top board and the surface of the top board, and before the heating means starts heating If the initial top plate temperature, which is the initial top plate temperature, is equal to or higher than the initial threshold, the heating means continues to stop heating until the top plate temperature drops by a predetermined temperature, and the top plate temperature is determined in advance. And a control unit that causes the gap distance determining means to start the determination of the gap distance when the temperature is lowered.

  In the cooking device of the present invention, when the initial tabletop temperature is equal to or higher than the initial threshold, the tabletop temperature detected by the tabletop temperature detection means is set to the target temperature for determination determined based on the initial tabletop temperature. In order to reach, heating for determination is performed in which the heating means heats at a constant heating power. Then, the gap distance is determined based on the rate of increase in the top plate temperature when the determination heating is performed. For this reason, it is possible to obtain a heating cooker that is balanced in improving the accuracy of detecting the gap distance and suppressing the increase in the temperature of the cooked food in the pan.

It is a top view of the heating cooker which concerns on embodiment. It is a block diagram explaining the structure and function of the principal part of the heating cooker which concerns on embodiment. It is a figure explaining the operation part and thermal-power display part which were provided corresponding to the left heating coil of the heating cooker which concerns on embodiment. It is a figure which shows the relationship between the clearance gap between a top plate and a pan bottom, and the increase value (output increase value) per unit time of the output of a top plate temperature detection part. It is a figure which shows the change of top-plate temperature with progress of time when a pan is mounted on a top-plate. It is an operation | movement flowchart of the fried food function of the heating cooker which concerns on embodiment. It is a figure which shows an example of transition of the heating electric power and top plate temperature of the preheating process of the heating cooker which concerns on embodiment. It is a flowchart explaining the operation | movement of the first half part of the preheating 1st process which concerns on embodiment. It is a flowchart explaining the clearance distance determination process of the preheating 1st process of the heating cooker which concerns on embodiment, and has shown operation | movement of the hot start A. FIG. It is a table | surface explaining the conditions which set the H-H flag and H-C flag of the heating cooker which concerns on embodiment. It is a clearance distance setting table for the hot start of the heating cooker which concerns on embodiment. It is a figure which shows the effect | action of the preheating 1st process in the case of the hot start A of the heating cooker which concerns on embodiment compared with the case where a clearance gap distance is large, and small. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start A of the heating cooker which concerns on embodiment. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start A of the heating cooker which concerns on embodiment. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start A of the heating cooker which concerns on embodiment. It is a flowchart explaining the gap distance determination process of the preheating 1st process of the heating cooker which concerns on embodiment, The operation | movement of the hot start B is shown. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start B of the heating cooker which concerns on embodiment. It is a flowchart explaining the clearance distance determination process of the preheating 1st process of the heating cooker which concerns on embodiment, and has shown operation | movement of the hot start C. FIG. It is a flowchart explaining the clearance distance determination process of the preheating 1st process of the heating cooker which concerns on embodiment, and has shown operation | movement of the hot start C. FIG. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start C of the heating cooker which concerns on embodiment. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start C of the heating cooker which concerns on embodiment. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start C of the heating cooker which concerns on embodiment. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start C of the heating cooker which concerns on embodiment. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start C of the heating cooker which concerns on embodiment. It is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start C of the heating cooker which concerns on embodiment. It is a clearance distance setting table for the cold start of the heating cooker which concerns on embodiment. It is a flowchart explaining the preheating 2nd process of the heating cooker which concerns on embodiment. It is an emissivity setting table of the heating cooker which concerns on embodiment. It is a correction coefficient setting table of the heating cooker which concerns on embodiment.

  Hereinafter, a case where the heating cooker according to the present invention is applied to a built-in type (built-in type) IH cooking heater in which two heating ports by induction heating are provided on the right and left sides and one on the back side of the center will be described as an example. In addition, this invention is not limited by the form of drawing shown below. Further, in the following description, terms for indicating directions (for example, “up”, “down”, “right”, “left”, “front”, “back”, etc.) are used as appropriate for easy understanding. This is for explanation and these terms do not limit the present invention.

Embodiment.
[Configuration of cooking device]
FIG. 1 is a top view of the cooking device according to the embodiment.
The cooking device 100 includes a main body 1 and a top plate 2 disposed on the upper surface of the main body 1, and an object to be heated such as a pan or a frying pan placed on the top plate 2 is placed inside the main body 1. It heats with the induction heating means provided in. In the present embodiment, heating ports 6 are respectively provided on the left front side, the right front side, and the center side back of the top plate 2. In the following description, the object to be heated may be referred to as “pan”.

  The top plate 2 is made of a material such as highly crystallized glass that has high heat resistance and transmits infrared rays. The top plate 2 is provided with a coating 13 (see FIG. 2) for making it difficult to see the internal structure from the outside. Moreover, the part corresponding to the heating port 6 of the top plate 2 is provided with, for example, a circular display indicating the place where the pan is placed by printing or the like, so that the user knows where the pan should be placed. It has become.

  On the front side of the upper surface of the main body 1, an operation unit 3 that receives an input operation of a heating condition or a heating instruction is arranged corresponding to each heating port 6. When a user places a pan or frying pan, which is an object to be heated, on the top plate 2 and inputs an operation to an operation key provided in the operation unit 3 corresponding to each heating port 6, induction heating is performed according to the operation input. The object to be heated is heated by the means. Information relating to settings such as the progress of heating and cooking mode is displayed on the display unit 4 having a liquid crystal or the like disposed on the top surface 2 corresponding to each heating port 6, and the heating power during heating is the heating power display unit. 5 is displayed.

  A high-temperature display unit 10 is provided on the substantially center front side of the top plate 2. The high temperature display unit 10 is provided with a high temperature display unit 10 that notifies the user that the top plate 2 is in a high temperature state. The high temperature display unit 10 includes, for example, a light emitting unit that emits red or orange light, a letter indicating that the top board 2 is in a high temperature state, and a light source that illuminates the letter, and the top board 2 is in a high temperature state. In some cases, the light emitting portion and the character are illuminated. In the present embodiment, three high-temperature display units 10 corresponding to the three heating ports 6 are provided, respectively, but one high-temperature display unit 10 that notifies when any one of the heating ports 6 is high temperature is provided. It is good also as the structure comprised.

  A heating coil 14 as a heating means is provided below the heating port 6 in the main body 1. In FIG. 1, the rough arrangement of the heating coil 14 is indicated by a broken line. An eddy current is generated in the pan placed on the top plate 2 by flowing a high-frequency current through the heating coil 14, and the pan bottom itself generates heat due to the generated eddy current and the resistance of the pan itself, so the pan bottom is directly heated. Cooking with good heating efficiency can be realized. In addition, you may provide other heating means, such as an electric heater, as a heating means of the heating port 6 of the heating cooker 100.

  In the top plate 2, a transmission window portion 7 having a substantially circular shape in plan view is provided inside the heating port 6. The transmissive window portion 7 is a region that has been subjected to a process that facilitates the transmission of infrared rays. For example, the top plate 2 is provided with a coating 13 for making the internal structure difficult to see from the outside (see FIG. 2), but the transmission amount of the coating is reduced or no coating is applied to the transmission window portion 7. Etc. are applied. By doing so, infrared rays are easily received by the infrared sensor 12 (see FIG. 2), which will be described later, provided in the main body 1 through the transmission window portion 7.

  A contact-type temperature sensor 17 such as a thermistor for detecting the temperature of the top plate 2 is provided on the lower surface (back surface) of the top plate 2. The contact-type temperature sensor 17 is provided inside the heating port 6 and is disposed so as to contact the lower surface (back surface) of the top plate 2. In the present embodiment, a plurality (two) of contact temperature sensors 17 are provided for one heating port 6. The two contact temperature sensors 17 are provided at positions shifted by about 180 degrees with respect to the center of the heating coil 14. The contact temperature sensor 17 is provided so as to be in close contact with the lower surface of the top plate 2 and outputs a signal corresponding to the temperature of the lower surface of the top plate 2. In addition, the number of the contact-type temperature sensors 17 provided corresponding to the heating port 6 is not limited, and can be one or plural.

  Behind the main body 1, there are intake ports 9 a and 9 b that take in air for cooling the inside of the main body 1 (hereinafter, may be collectively referred to as the intake port 9), and an exhaust port 8 that exhausts air in the main body 1. Provided. When the air blowing means (not shown) provided in the main body 1 operates, external air flows into the main body 1 from the intake port 9 as cooling air, and the cooling air is sent to the inside of the main body by a substrate (not shown), elements, and induction heating means. A certain heating coil 14, the lower surface of the top plate 2, and the like are cooled. The cooling air after cooling the inside of the main body 1 is discharged from the exhaust port 8 to the outside.

FIG. 2 is a block diagram illustrating the configuration and function of the main part of the heating cooker according to the embodiment. In FIG. 2, only the structure corresponding to one heating port 6 is illustrated, and a pan 200 as an object to be heated is also illustrated.
A heating coil 14 is disposed below the heating port 6 provided in the top plate 2. In the present embodiment, the heating coil 14 has a double ring shape including a substantially annular inner heating coil 14a and a substantially annular outer heating coil 14b provided outside thereof. A substantially annular space (gap) is provided between the inner heating coil 14 a and the outer heating coil 14 b, and this gap is referred to as a gap 15. The heating coil 14 is held at a predetermined distance from the lower surface of the top plate 2 by a heating coil support 16 that accommodates the heating coil 14.

  An infrared sensor 12 is provided in the gap 15 between the inner heating coil 14a and the outer heating coil 14b and below the upper surface of the heating coil 14 to output an output corresponding to the detected infrared amount when detecting infrared rays. Yes. The output from the infrared sensor 12 is input to an infrared temperature detection unit 24 provided in the main body 1. The infrared temperature detector 24 is an infrared temperature detector that converts the output value from the infrared sensor 12 into a temperature. More specifically, the storage unit 21 stores in advance a temperature conversion table in which the output amount of the infrared sensor 12 is associated with the temperature data calculated based on the output amount and a predetermined emissivity. When receiving the output from the infrared sensor 12, the infrared temperature detecting unit 24 refers to the temperature conversion table and calculates the temperature. As an example of the emissivity ε used in the temperature conversion table, ε = 1.0 is set. Moreover, in this Embodiment, the temperature which the infrared temperature detection part 24 detects based on the amount of infrared rays which the infrared sensor 12 detected is called infrared temperature.

  As the infrared sensor 12, a sensor having sensitivity in a wide wavelength with respect to an infrared region, such as a thermopile sensor, is used. Although the specific configuration of the infrared sensor 12 is not particularly limited, for example, a condensing lens type thermopile sensor in which a convex condensing lens, a thermopile chip, and a self-temperature detection thermistor are packaged, a reflector, a thermopile chip, and A built-in mirror condensing type thermopile sensor or the like in which a self-temperature detection thermistor is packaged can be used. Note that a band pass filter having transmission characteristics in a wavelength band with a high transmittance of the top plate 2 can be provided on the condensing surface of the infrared sensor 12. By doing so, the infrared sensor 12 can efficiently detect the infrared light transmitted through the top plate 2.

  The infrared sensor 12 is covered with a sensor case 18 so that the cooling air flowing in the vicinity of the heating coil 14 is not directly hit. The infrared sensor 12 is held in the sensor case 18 while maintaining a spatial distance so that the ambient temperature around the infrared sensor 12 is uniform. The sensor case 18 is fixed to the heating coil support portion 16 with a tapping screw or the like, or partly formed integrally with the heating coil support portion 16, and the distance between the top plate 2 and the infrared sensor 12. Is kept constant.

  In the present embodiment, in order to detect infrared rays emitted from the bottom of the pan and passing through the top plate 2, it is desirable that the transmission window portion 7 on the upper surface portion of the infrared sensor 12 does not have the coating 13. However, if the transmissive window 7 is not coated, the internal heating coil 14 and wiring may be visible from the top surface of the top plate 2, which is not desirable in design. For this reason, when the coating 13 is not applied to the transmission window portion 7, a cylinder or a plate is provided on the heating coil support portion 16 or the sensor case 18 that holds the heating coil 14 toward the top plate 2. What is necessary is just to make it difficult to see the heating coil 14, wiring, etc. from the outside by doing in this way. In addition, instead of covering the entire surface of the transmission window portion 7 with the coating 13, the coating 13 is applied to the transmission window portion 7 in the form of dots or stripes so as to manage the ratio of the unpainted openings. Well, it is possible to ensure design and functionality by doing so.

  The contact temperature sensor 17 is provided in an annular gap 15 between the inner heating coil 14a and the outer heating coil 14b. The output signal of the contact temperature sensor 17 is input to the top plate temperature detector 25 provided in the main body 1. The top plate temperature detector 25 detects the temperature of the top plate 2 based on a signal from the contact temperature sensor 17. In the present embodiment, the contact-type temperature sensor 17 and the top plate temperature detection unit 25 constitute the top plate temperature detection means of the present invention. In the present embodiment, the temperature detected by the top temperature detector 25 based on the output from the contact temperature sensor 17 is referred to as the top temperature. Further, as long as the temperature of the top plate 2 can be detected more accurately with little time delay, not only the contact-type temperature sensor 17 such as a thermistor, but any one can be adopted as the top plate temperature detecting means. .

  In the present embodiment, the contact temperature sensor 17 is provided in the gap 15 between the inner heating coil 14a and the outer heating coil 14b. However, the arrangement of the contact temperature sensor 17 is not limited to this. For example, the contact temperature sensor 17 may be disposed in the vicinity of the outer periphery of the outer heating coil 14 b or may be disposed in the center of the heating coil 14. Moreover, the number of the contact-type temperature sensors 17 is not limited to two, and may be one or two or more.

The output of the contact-type temperature sensor 17 is used when calculating the temperature of the pan 200 based on the amount of infrared rays detected by the infrared sensor 12 as will be described later. For this reason, in order to detect the temperature of the pan 200 with higher accuracy, the contact-type temperature sensor 17 is preferably installed in the vicinity of the infrared sensor 12.
In addition, since it is indefinite where the pan 200 is mounted on the top plate 2 and the shape of the pan 200 is also indefinite, a wider range of temperatures can be detected and realized at low cost. Prioritizing this, the contact-type temperature sensor 17 and the infrared sensor 12 may be arranged separately.

  Moreover, when the number of the contact-type temperature sensors 17 is small, the detected temperature may vary depending on the position and shape of the pan placed on the top plate 2. For this reason, the average value of the detection values of the plurality of contact-type temperature sensors 17 and the detection value of the output of the highest temperature among the plurality of contact-type temperature sensors 17 are used for temperature detection of the pan 200 described later. It may be. By doing in this way, even when the number of installation of the contact-type temperature sensor 17 is small, temperature detection resistant to variations can be performed. In the present embodiment, an average value of detection values of a plurality of contact temperature sensors 17 provided for one heating port 6 is used as the temperature of the top plate 2 corresponding to the heating port 6. .

  The storage unit 21 provided in the main body 1 receives and stores information set by the operation unit 3 and outputs from the infrared temperature detection unit 24 and the top plate temperature detection unit 25.

  The calculation unit 22 is configured by, for example, a microcomputer and performs calculation processes (gap distance determination process, heated object temperature detection process, and emissivity estimation process) related to temperature detection of the pan 200 placed on the top 2. To do. The calculation result of the calculation unit 22 is input to the control unit 23. The calculating part 22 is corresponded to the clearance distance determination means, to-be-heated object temperature detection means, and emissivity estimation means of this invention.

  The control unit 23 controls the high-frequency inverter 26 based on the setting content of the operation unit 3 and the temperature information of the pan 200 detected by the calculation unit 22, and controls the high-frequency current flowing through the heating coil 14. By doing in this way, the heating control of the pan 200 which is an object to be heated is performed.

  Drawing 3 is a figure explaining the operation part and thermal-power display part provided corresponding to the left heating coil of the cooking-by-heating machine concerning an embodiment. Since the operation unit 3 and the thermal power display unit 5 respectively corresponding to the heating coil 14 provided on the left side, the right side, and the center of the heating cooker 100 have the same configuration, here, they correspond to the left heating coil 14. The operation unit 3 and the thermal power display unit 5 provided as an example will be described as an example.

The operation unit 3 includes a heating power setting key 31 for setting a heating power for heating the object to be heated, and a menu key 32 for setting a cooking menu.
The heat setting key 31 includes a “low heat” key, a “medium fire” key, a “high fire” key, and a “3 kW” key, and the user can use any of the four levels of fire power using these keys. Can be set. By providing keys individually according to the thermal power, the user can input the necessary thermal power settings with a single operation.

  The menu key 32 includes a “fried food” key, a “preheat” key, a “boiled” key, and a “timer” key. When these keys are pressed, the control unit 23 performs heating control according to a control sequence preset for each menu and stored in the storage unit 21.

  The thermal power display unit 5 displays the thermal power being heated by the heating coil 14 in a plurality of stages, and the display mode is switched according to the thermal power. The display of the thermal power display unit 5 can indicate to the user that the heating coil 14 is performing a heating operation. The thermal power display unit 5 includes, for example, a plurality of LEDs, and expresses thermal power by switching the lighting states (lighting, extinguishing, blinking, etc.) of these LEDs or switching the lighting color. By doing in this way, the user can perform notification which is easy to understand intuitively.

  Although not shown in FIG. 3, the display unit 4 (see FIG. 1) configured with a liquid crystal screen or the like has, for example, a thermal power and progress status such as “during preheating” and “appropriate temperature reached”, set menus, etc. Information on the contents of the is displayed.

  In the cooking device 100 having such a configuration, for example, when fried food cooking is performed, the user puts oil for performing fried food in the pan and places the pan on the heating port 6 of the top plate 2. When the user inputs the “fried food” key provided on the menu key 32 of the operation unit 3 to instruct the start of heating, the control unit 23 heats based on the signal from the operation unit 3 and the estimated temperature of the pan. A high-frequency current flowing in the coil 14 is applied, and the pan is heated by this.

[Temperature detection processing of heated object]
(Overview)
The arithmetic unit 22 detects the temperature of the pan based on the infrared energy detected by the infrared sensor 12 during heating of the pan. The infrared sensor 12 detects the infrared energy emitted from the bottom of the pan and the top plate 2. As a result of being heated by heat transfer, infrared energy radiated from the lower surface of the top plate 2 is detected. Then, the calculating part 22 estimates the temperature of a pan, after removing the infrared energy radiated | emitted from the top plate 2 from the infrared energy which the infrared sensor 12 detected.

  In the pan temperature estimation process according to the present embodiment, when the temperature of the pan is estimated by subtracting the influence of the top plate 2 from the temperature detected by the infrared temperature detector 24, the bottom of the pan and the surface of the top plate 2 A gap distance determination process for determining the gap distance between the two and an emissivity estimation process for estimating the emissivity of the bottom surface of the pan. Hereinafter, the outline of each process will be described.

(Gap distance determination processing)
The gap distance determination process is a process of determining a gap distance between the bottom surface of the pan and the surface of the top plate 2. Here, the gap distance refers to the distance of the gap between the bottom surface of the pan and the surface of the top plate 2, and refers to the height at which the bottom surface of the pan floats from the surface of the top plate 2. When the bottom of the pan is warped or when an object is sandwiched between the top plate 2 and the pan, a gap (air layer) is created between the bottom of the pan and the top plate 2, The height of the gap is the gap distance.

  FIG. 4 is a diagram illustrating the relationship between the gap distance between the top plate and the pan bottom and the increase value (output increase value) per unit time of the output of the top plate temperature detection unit. FIG. 4 shows a graph when the top plate 2 is in a normal temperature state and when the top plate 2 is in a high temperature state. As shown in FIG. 4, the larger the gap distance, the smaller the output increase value of the top temperature detector 25.

For example, the heat conductivity of a stainless steel pan is 16 W / (m · K) and the heat conductivity of the top plate 2 is 1.5 W / (m · K), whereas the heat transfer coefficient of air is 0.024 W. / (M · K) and a very small value. For this reason, if the gap distance between the pan bottom and the top plate 2 is 0.5 mm, the temperature rise amount of the top plate 2 detected by the contact-type temperature sensor 17 becomes small. For this reason, as shown in FIG. 4, the greater the gap distance between the pan bottom and the top plate 2, the less the infrared energy that reaches the top plate 2, and the temperature rise value detected by the contact temperature sensor 17. Becomes smaller.
Therefore, the gap distance between the pan bottom and the surface of the top plate 2 can be determined by the rate of temperature increase detected by the contact-type temperature sensor 17.

  In the gap distance determination process for determining the gap distance, a detailed determination method will be described later. In the initial stage of heating, heating by the heating coil 14 is performed until the temperature of the top 2 reaches the target temperature for determination. The gap distance is determined based on the temperature rise rate of the top plate 2. The output of the contact temperature sensor 17 used for the determination of the gap distance may be an average value of the output values of the plurality of contact temperature sensors 17 or indicates the highest temperature among the output values of the plurality of contact temperature sensors 17. A value may be used, or a value obtained by averaging the upper two output values for detecting a high temperature among the output values of the plurality of contact temperature sensors 17 may be used. As described above, by using the output values of the plurality of contact-type temperature sensors 17, it is possible to suppress variations in temperature detection.

  In addition, the determination of the gap distance in the initial stage of heating is based on the characteristics of the oil in the pan used in fried food cooking. That is, when oil is used in deep-fried food cooking, the viscosity of the oil is high, and the temperature rises almost uniformly without convection even after the heating power is added. As the oil temperature rises, the viscosity decreases and the convection starts and the heat diffuses. However, if the heating is performed for a predetermined time, for example, about 50 seconds, the bottom of the pan is almost constant regardless of the amount of oil. Become.

  Thus, the gap distance, which is the height of the gap between the pan bottom and the top plate 2, can be estimated using the temperature increase value of the contact-type temperature sensor 17 in the initial stage of heating.

Further, as shown in FIG. 4, when the gap distance is the same, when the temperature of the top plate 2 is high, the output increase value of the top plate temperature detector 25 is smaller than when the temperature is normal. It can be seen that the temperature rise value of the top plate temperature detector 25 is affected by the temperature of the top plate 2 in the initial state.
Therefore, in the present embodiment, the temperature of the top plate 2 is taken into account when detecting the gap distance in the gap distance determination process.

  FIG. 5 is a diagram showing a change in the top plate temperature over time when the pan is placed on the top plate, and when the pan is placed on the top plate 2 (0 second). The change until 60 seconds elapse is shown. FIG. 5 illustrates changes in the temperature of the top plate 2 when cooking is performed on the top plate 2 at a high temperature. The graph shown in FIG. 5 is the same as the top plate 2 on the high temperature top plate 2 when a pan having a temperature higher than the top plate 2 is placed on the high temperature top plate 2 in order from the top. It is a graph when a pan having a temperature lower than that of the top plate 2 is placed on the hot top plate 2 (reference number 43) when a pan having a certain temperature is placed (reference number 42).

When the top plate 2 is in a high temperature state, it means that the pan was heated on the top plate 2 before that, but the pan was placed depending on the temperature of the pan placed on the top plate 2. The temperature change of the top board 2 after being done is different.
As indicated by reference numeral 41, when a pan having a temperature higher than the top plate 2 is placed on the high temperature top plate 2, the top plate temperature rises with time. Further, as indicated by reference numeral 42, when a pan having a temperature similar to that of the top plate 2 is placed on the high temperature top plate 2, it is almost flat, but the top plate temperature decreases with the passage of time. I will do it. Further, as indicated by reference numeral 43, when a pan having a temperature lower than that of the top plate 2 is placed on the high temperature top plate 2, the top plate temperature is greatly reduced as compared with the graph indicated by reference numeral 42.

Thus, the temperature of the top plate 2 detected by the top plate temperature detector 25 is affected by the temperature of the pan placed on the top plate 2.
Therefore, in the present embodiment, the temperature difference between the top plate 2 and the pan is taken into account when detecting the gap distance based on the temperature rise value of the top plate temperature detector 25 in the gap distance determination process. Specifically, when the pan is hotter than the top plate 2, an HH flag (top plate Hot-pan hot flag) is given, and when the pan is colder than the top plate 2, A flag (top plate Hot-pan Cold flag) is assigned to distinguish them from others, and the information is taken into the determination of the gap distance.

(Emissivity estimation processing)
As described above, the ratio of the amount of infrared energy detected by the infrared sensor 12 varies depending on the temperature of the pan and the temperature condition of the top plate 2, but the infrared emissivity ε of the pan bottom is also detected by the infrared sensor 12. It is a variable factor. In particular, since a pan with various emissivities ε can be placed in a heating cooker like this embodiment, various conditions are assumed for emissivity ε, for example, from 0.1 to 0.9. For this reason, in order to estimate the temperature of the pan with high accuracy, it is desirable to use a highly accurate value as the emissivity ε of the bottom surface of the pan placed on the top 2.
Therefore, in the present embodiment, emissivity estimation processing is performed for estimating the emissivity ε of the pan bottom based on the temperature rise value from the start of heating detected by the infrared temperature detection unit 24 until a predetermined time has elapsed.

  In the emissivity estimation process of the present embodiment, the emissivity of the pan bottom is determined by the temperature rise value detected by the infrared temperature detecting unit 24 after a predetermined time has elapsed from the start of heating. Comparing the temperature rise value of the infrared temperature detection unit 24 for a predetermined time, the temperature rise value becomes large at the pan bottom with high emissivity, and the temperature rise value becomes small at the pan bottom with low emissivity. Determine the emissivity of the pan bottom.

  Moreover, in this Embodiment, after the above-mentioned clearance distance determination process is complete | finished, based on the temperature rise value detected by the infrared temperature detection part 24, the emissivity of a pan is estimated. Information that is detected by the infrared temperature detection unit 24 using the known gap distance by starting the determination of the emissivity of the pan using the infrared temperature detection unit 24 after the gap distance determination is completed. It can correct | amend and can improve the detection accuracy of a temperature rise value. That is, the infrared radiation ratio from the top plate 2 is large when there is no gap distance (small), and small when the gap distance is large. Reflect in detection results. In addition, the measurement by the infrared temperature detection part 24 may be started before the gap distance determination process is completed, and the result of the pot gap distance determination may be fed back to the measurement result.

[Operation of cooking device]
(Overview of operation)
The heating control in the heating cooker 100 of this Embodiment and the to-be-heated object temperature detection process which detects the temperature of to-be-heated material are demonstrated to a fried food cooking as an example. FIG. 6 is an operation flowchart of the deep-fried food function of the heating cooker according to the embodiment.
It is assumed that a pan, which is an object to be heated, is placed in the heating port 6 of the top plate 2. When “fried food” is selected with the menu key 32 of the operation unit 3, the process of the flowchart of FIG. 6 starts.

(S1)
The control unit 23 sets a preheating target temperature, which is a target temperature for preheating the pot, based on a user input to the operation unit 3. The preheating target temperature may be directly input to the operation unit 3 by the user, for example, “180 ° C.”, or the user may select a cooking menu such as “tempura”, “tonkatsu”, “kara fried”, etc. The controller 23 may select a preheating target temperature set in advance according to the input cooking menu.

(S2)
A preheating first step including the above-described gap distance determination process is executed. When the determination of the gap distance is completed, the process proceeds to the next step.

(S3)
The preheating second step of adjusting the temperature so that the temperature of the pan becomes the preheating target temperature is executed. The temperature of the pan is detected based on the results of the gap distance determination process and the emissivity estimation process described above. When the detected temperature of the pan reaches the preheating target temperature, the preheating second step is terminated and the process proceeds to the next step.

(S4)
The control unit 23 uses the display unit 4 to notify that the preheating has been completed. Instead of or in addition to the notification by the display unit 4, a voice notification unit (not shown) such as a buzzer or a speaker may be used to notify the end of preheating.

(S5)
The controller 23 controls the electric power supplied to the heating coil 14 to keep the temperature of the pan at the preheating target temperature. In this heat retention step, the pan temperature is estimated in the same manner as the heated object temperature detection process in step S3, and the pan temperature is kept at the preheating target temperature. In this heat retention step, the user can put the ingredients into the pot and cook the fried food.

(S6)
The controller 23 continues the heat retaining process until a predetermined time has elapsed from the start of heat retaining. This predetermined time is a time set in advance to automatically stop heating even when the user forgets to stop heating.

(S7)
When a predetermined time has elapsed from the start of heat retention, the control unit 23 stops the power supply to the heating coil 14 and stops the heating. In addition, when the operation instruction | indication of a heating stop is input into the operation part 3 before predetermined time passes, the control part 23 stops heating according to the operation instruction.

(Outline of preheating first process and preheating second process)
Next, the outline of the preheating first process and the preheating second process of the heating cooker according to the present embodiment will be described.
Drawing 7 is a figure showing an example of transition of heating electric power and top plate temperature of a preheating process of a cooking-by-heating machine concerning an embodiment. As shown in FIG. 7, in the first preheating step, based on the temperature of the top plate 2 before the start of heating when an instruction to start heating is input to the operation unit 3 (initial top plate temperature TH_0s), The cases are classified into “hot start A”, “hot start B”, “hot start C”, and “cold start”. Then, the gap distance is determined based on the temperature rise rate (ΔTH_2 / Time_B) of the top plate temperature when electric power is supplied to the heating coil 14 for heating. Here, heating the pan for gap distance determination is referred to as gap distance determination heating (hereinafter, determination heating). The determination heating process differs depending on whether “hot start A”, “hot start B”, “hot start C”, or “cold start” is applicable. In FIG. 7, an example of transition of the top plate temperature in the case of hot start A is shown.

  Further, in the present embodiment, in the case of “Hot Start A”, “Hot Start B”, and “Hot Start C”, a standby time during which no heating is performed is provided before the heating for determination. The top plate temperature change (ΔTH_1) is used for the determination of the gap distance.

  And if the preheating 1st process which performs a clearance gap determination process is complete | finished, it will transfer to a preheating 2nd process. In the second preheating step, a heated object temperature detection process for detecting the temperature of the pan is performed based on the gap distance determined in the first preheating step, and power is supplied to the heating coil 14 so that the pan temperature becomes the preheating target temperature. To perform temperature adjustment heating. As FIG. 7 shows, the temperature of the top plate 2 also rises by heating a pan. And if the temperature of a pan reaches preheating target temperature, a preheating 2nd process will be complete | finished.

  Next, the preheating first step and the preheating second step will be specifically described.

(Preheating first process)
FIG. 8 is a flowchart for explaining the operation of the first half of the first preheating step according to the embodiment.
At the start of the flow in FIG. 8, it is assumed that no power is supplied to the heating coil 14 and heating is not performed.
When the preheating start instruction is received (S10), the calculation unit 22 detects the initial top plate temperature TH_0s of the top plate 2 based on the output from the top plate temperature detector 25 (S11). That is, the temperature of the top 2 before starting heating is detected as the initial top temperature TH_0s.

  The computing unit 22 compares the initial top board temperature TH_0s with a preset high temperature initial threshold value (eg, 140 ° C.), medium temperature initial threshold value (eg, 80 ° C.), and low temperature initial threshold value (eg, 40 ° C.) (S12 to S12). S14). If the initial top board temperature TH_0s is equal to or higher than the high temperature initial threshold value, the hot start C process is executed (S15). If the initial top board temperature TH_0s is equal to or higher than the medium temperature initial threshold value and lower than the high temperature initial threshold value, the hot start B process is executed. (S16), if the initial top board temperature TH_0s is not less than the low temperature initial threshold value and less than the medium temperature initial threshold value, the hot start A process is executed (S17). If the initial top board temperature TH_0s is less than the low temperature initial threshold value, Normal (cold start) pre-heat treatment is executed (S18).

  Next, the “hot start A”, “hot start B”, “hot start C”, and “cold start” will be described for the gap distance determination process that is the latter half of the first preheating step.

(Hot start A)
FIG. 9 is a flowchart for explaining the gap distance determination process in the first preheating step of the heating cooker according to the embodiment, and shows the operation of hot start A.

  The calculation unit 22 starts counting up the time counter A (S101). At this time, the heating coil 14 is in a power OFF state (S102), and the calculation unit 22 waits until the time counter A counts 60 seconds with the power OFF. When the standby time of 60 seconds elapses (S103; Yes), the temperature TH_60s of the top 2 at that time is measured and stored in the storage unit 21 (S104). Next, the calculating part 22 calculates temperature difference (DELTA) TH_1 which is the difference of the temperature TH_60s of the top plate 2 and the initial top plate temperature TH_0s after 60 seconds of standby time (S105).

When the temperature difference ΔTH_1 is equal to or higher than the preset threshold value Ut ° C., that is, when the temperature of the top 2 rises above Ut ° C. during the standby time of 60 seconds (S106; Yes), It is determined that the pan is hotter than the top 2 and the H-H flag is set (S107).
In addition, when the temperature difference ΔTH_1 is equal to or less than a preset threshold value −Dt ° C., that is, when the temperature of the top 2 has decreased by Dt ° C. or more during the standby time of 60 seconds (S108; Yes), it is determined that the pan is colder than the top plate 2, and the HC flag is set (S109).

Here, the H-H flag and the HC flag will be described.
FIG. 10 is a table for explaining conditions for setting the H-H flag and the H-C flag of the cooking device according to the embodiment. The H-H flag and the H-C flag are set based on the temperature difference (ΔTH_1) between the initial top board temperature TH_0s and the temperature TH_60s when the standby time has elapsed for 60 seconds. In this embodiment, the threshold value of the temperature difference for setting each flag is made different depending on whether the hot start is A, B, or C. In the case of hot start A, the threshold value Ut ° C. = 8 ° C., the HH flag is set when the temperature TH_60s is increased by 8 ° C. or more with respect to the initial top board temperature TH_0s, and the threshold value −Dt HC = −5 ° C., and the HC flag is set when the temperature TH_60s is lower than the initial top board temperature TH_0s by −5 ° C. or more.

  When the H-H flag or the H-C flag is set, heat transfer between the pan and the top plate 2 is good, that is, it can be said that the top plate 2 and the pan bottom are close and the gap distance is relatively small. .

In FIG. 9, when the temperature of the top 2 does not rise above Ut ° C. during the standby time of 60 seconds (S106; No) and does not drop above Dt ° C. (S108; No), H− The H flag and the HC flag are not set.
Thus, in steps S101 to S109, the level relationship between the top plate temperature and the pan temperature is determined based on the change in the top plate temperature when waiting while heating is stopped. In addition, you may determine the high / low relationship between a top plate temperature and a pan temperature, heating not by completely stopping in standby time, but heating by a low heating power rather than the heating for determination mentioned later.

The description of FIG. 9 is continued.
Next, the calculation unit 22 starts counting up the time counter B (S110), the control unit 23 inputs a constant power (750 W in the present embodiment) to the heating coil 14 (S111), and the top plate 2 The target heating temperature for determination is set to 100 ° C., and heating for determination is performed. When the current temperature TH_cur of the top 2 detected by the top temperature detector 25 is equal to or higher than the determination target temperature (100 ° C.) (S112; Yes), the calculation unit 22 proceeds to step S113.

  Here, the electric power supplied to the heating coil 14 in step S111 is not limited to 750 W, but if the electric power supplied is too large, the temperature of the pan may rise excessively during the heating for determination. For this reason, in this Embodiment, it is set as the moderate electric power with respect to the maximum electric power of the heating coil 14. FIG. Moreover, although the target temperature for determination of the top plate 2 used for determination in step S112 is not limited to 100 ° C., it is set to a temperature lower than the lowest temperature (for example, 160 ° C.) that can be set as the preheating target temperature for fried food cooking. The higher the target temperature for determination can increase the temperature increase width in the heating for determination, so that it is possible to improve the determination accuracy of the gap distance determined based on the rate of temperature increase in the heating for determination. In addition, if the target temperature for determination is too high, it takes time to determine the gap distance, and if the gap distance is large, the pan may become excessively hot.

  Next, the calculation unit 22 stores Time_B, which is the value of the time counter B when the temperature TH_cur of the top plate 2 is equal to or higher than the determination target temperature (100 ° C.), in the storage unit 21 (S113). A temperature difference ΔTH_2 which is a difference between the target temperature (100 ° C.) and the temperature TH_60s after the standby time of 60 seconds is calculated (S114). This temperature difference ΔTH_2 is the rise in the temperature of the top plate 2 from when the heating of the heating coil 14 is started with 750 W electric power until the temperature of the top plate 2 reaches the determination target temperature (100 ° C.). Amount.

  Next, the calculation unit 22 divides the temperature difference ΔTH_2 by Time_B, that is, determines the amount of temperature rise of the top 2 from the start of heating by the heating coil 14 to the determination target temperature (100 ° C.). By dividing by the time required to reach the target temperature for use (100 ° C.), the temperature increase rate of the top 2 is calculated (S115). Next, the calculation unit 22 compares the calculated temperature rise rate of the top board 2 and the presence or absence of the H-H flag and the H-C flag with the gap distance setting table illustrated in FIG. Determination is made (S116).

  Here, FIG. 11 is a gap distance setting table for hot start of the cooking device according to the embodiment. The gap distance setting table shown in FIG. 11 is a table in which the temperature increase rate of the top plate 2 is associated with the gap distance. In the present embodiment, the gap distance is divided into 8 stages of G1 to G8 (the gap distance increases sequentially from G1 to G8). Further, in FIG. 11, when the H-H flag and the HC flag are not set (no flag), when the H-H flag is set, and when the HC flag is set, respectively. The gap distance is set. This gap distance setting table is a table of values obtained through experiments or the like, and is stored in the storage unit 21 in advance.

  When the calculation unit 22 determines the gap distance with reference to FIG. 11, the calculation unit 22 stores the gap distance in the storage unit 21 and ends the gap distance determination process.

  On the other hand, in step S112 in FIG. 9, the temperature TH_cur of the top 2 does not reach the determination target temperature (100 ° C.) (S112; No), and the value of the time counter B has passed 400 seconds (first time limit). If it is determined (S117; Yes), the calculation unit 22 determines that the gap distance is level G7 (S118), and ends the gap distance determination process of FIG. That is, 750 W of electric power is applied to the heating coil 14 to perform heating for determination, and the temperature of the top 2 does not reach the determination target temperature (100 ° C.) even after 400 seconds (first time limit) has elapsed. That is, since the gap distance is large, it is determined that the heat transmitted from the pan to the top plate 2 is small, and the gap distance is determined as G7 which is a relatively high level value. In this way, by setting an upper limit value for the heating time for determination in which power is supplied to the heating coil 14 in the gap distance determination process, even if the gap distance is large, the pot is in the middle of the gap distance determination process. Excessive heating can be suppressed.

Next, the operation when the cooking device of the present embodiment performs the operation shown in FIG. 9 will be described by comparing the case where the gap distance is relatively large and the case where the gap distance is relatively small.
FIG. 12 is a diagram showing the action of the first preheating step in the case of hot start A of the heating cooker according to the embodiment, in comparison with a case where the gap distance is large and a case where the gap distance is small. In FIG. 12, the relationship between the temperature of the top plate 2 detected by the top plate temperature detection unit 25 based on the detection value of the contact temperature sensor 17, the temperature of oil in the pan, and the power input to the heating coil 14 is shown. Yes.

  As shown in FIG. 12, when the gap distance is large, the time Time_B from when the power of 750 W is applied to the heating coil 14 until the temperature of the top 2 reaches the determination target temperature (100 ° C.) is It is longer than Time_B when the gap distance is small. When the gap distance is large, the top plate 2 is heated until the temperature reaches the target temperature for determination (100 ° C.). This heating time is longer than when the gap distance is small, and the temperature of the oil in the pan is It rises. For this reason, when the temperature of the oil in the pan when the temperature of the top plate 2 reaches 100 ° C. is compared, when the gap distance is large, the temperature becomes higher than when the gap distance is small.

  Next, the effect | action of the preheating 1st process in the case of the hot start A implement | achieved by the flowchart shown in FIG. 9 is demonstrated paying attention to the temperature of the top plate 2, and the input electric power to the heating coil 14. FIG.

  FIG. 13: is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start A of the heating cooker which concerns on embodiment. In FIG. 13, in the case of hot start A, changes in the top board temperature and the input power to the heating coil 14 when the HH flag is set are shown.

  The initial top board temperature TH_0s is not less than the low temperature initial threshold (40 ° C.) and less than the medium temperature initial threshold (80 ° C.). During the standby time of 60 seconds from the start of the preheating process (0 s), the power supply to the heating coil 14 is stopped, the pan is not heated, and the top plate 2 is transferred by heat transfer from the pan placed on the top plate 2. The temperature gradually rises. Since the temperature rise amount of the temperature TH_60s with respect to the initial top board temperature TH_0s when the standby time of 60 seconds has passed is equal to or higher than the HH flag threshold (8 ° C.) (step S106 in FIG. 9; Yes), HH A flag is set.

  Next, when electric power of 750 W is input to the heating coil 14 and heating for determination is started, the pan is heated, and the top plate temperature rises due to heat transfer from the pan, and the top plate temperature is determined. The target temperature (100 ° C.) is reached (step S112 in FIG. 9; Yes). Then, the time (Time_B) from the start of heating for determination (60 s) until the top plate temperature reaches the target temperature for determination (100 ° C.), and the top plate temperature from the start of heating for determination to the target temperature for determination (100 ° C. ) Is calculated based on the temperature rise amount (ΔTH_2) until it reaches (). Subsequently, the gap distance is determined from the temperature increase rate and the H-H flag with reference to FIG.

  FIG. 14: is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start A of the heating cooker which concerns on embodiment. FIG. 14 shows changes in the top board temperature and the input power to the heating coil 14 when the HC flag is set in the hot start A.

  During the standby time of 60 seconds from the start of the preheating process (0 s), the power supply to the heating coil 14 is stopped and the pan is not heated, and the heat is transferred from the low-temperature pan placed on the top plate 2 by the heat transfer. The temperature of the plate 2 gradually decreases. Since the temperature decrease amount of the temperature TH_60s with respect to the initial top board temperature TH_0s when the standby time of 60 seconds has passed is equal to or higher than the HC flag threshold (−5 ° C.) (step S108 in FIG. 9; Yes), The C flag is set.

  Next, when electric power of 750 W is input to the heating coil 14 and heating for determination is started, the pan is heated, and the top plate temperature rises due to heat transfer from the pan, and the top plate temperature is determined. The target temperature (100 ° C.) is reached (step S112 in FIG. 9; Yes). Then, the time (Time_B) from the start of heating for determination (60 s) until the top plate temperature reaches the target temperature for determination (100 ° C.), and the top plate temperature from the start of heating for determination to the target temperature for determination (100 ° C. ) Is calculated based on the temperature rise amount (ΔTH_2) until it reaches (). Subsequently, the gap distance is determined from the temperature increase rate and the HC flag with reference to FIG.

  FIG. 15: is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start A of the heating cooker which concerns on embodiment. FIG. 15 shows changes in the top plate temperature and the input power to the heating coil 14 when the top plate temperature hardly changes during the standby time in the hot start A.

  During the standby time of 60 seconds from the start of the preheating process (0 s), the power supply to the heating coil 14 is stopped, the pan is not heated, and the top plate temperature is somewhat lowered, but the change is almost flat. . The temperature increase amount and temperature decrease amount of the temperature TH_60s with respect to the initial top plate temperature TH_0s when the standby time of 60 seconds elapses are not equal to or higher than the HH flag threshold value and the HC flag threshold value (step of FIG. 9). S106; No, S108; No), the H-H flag and the H-C flag are not set.

  Next, when electric power of 750 W is input to the heating coil 14 and heating for determination is started, the pan is heated, and the top plate temperature rises due to heat transfer from the pan, and the top plate temperature is determined. The target temperature (100 ° C.) is reached (step S112 in FIG. 9; Yes). Then, the time (Time_B) from the start of heating for determination (60 s) until the top plate temperature reaches the target temperature for determination (100 ° C.), and the top plate temperature from the start of heating for determination to the target temperature for determination (100 ° C. ) Is calculated based on the temperature rise amount (ΔTH_2) until it reaches (). Subsequently, the gap distance is determined from the temperature increase rate with reference to FIG.

  The fact that the H-H flag or the H-C flag is set as shown in FIGS. 13 and 14 indicates that heat transfer from the pan to the top plate 2 is good, and therefore the gap distance is compared. It can be said that it is short. The difference between the case of FIG. 13 and the case of FIG. 14 is the temperature of the pan placed on the top plate 2. As shown in FIG. 11, in the present embodiment, when the temperature rise rate is the same, when a pan having a higher temperature than the top plate 2 is placed (with an HH flag), the temperature is lower than that of the top plate 2. It is determined that the gap distance is larger than when the pan is placed (with the HC flag) (except when the temperature increase rate is less than 0.1). In this way, when heating a hot pot, the gap distance is determined to be large, so that the temperature of the pot detected using the correction coefficient setting table of FIG. As a result, even if an error occurs in the determination of the gap distance, it is possible to suppress an excessively high temperature of the pan. In other words, at the same rate of temperature increase, when a pan having a temperature lower than the top plate 2 is placed (with the HC flag), a pan having a temperature higher than the top plate 2 is placed (H It is determined that the gap distance is smaller than (with -H flag) (except for the case where the temperature increase rate is less than 0.1). When a low-temperature pan is placed, the time required for the temperature of the top plate 2 to rise is relatively long even with the same gap distance. can do.

  On the other hand, as shown in FIG. 15, when the H-H flag and the H-C flag are not set, the gap distance is small but the pan and the top plate temperature are almost the same, or the gap distance is large, so It can be said that the heat transfer to the plate 2 is small. In this case, although the gap distance cannot be estimated from the temperature change of the top plate during the standby time, the temperature rise rate increases as the gap distance is closer based on the temperature rise rate of the top plate 2 during the heating for determination. This is used to determine the gap distance.

  Thus, the gap distance can be more accurately determined regardless of the temperature level of the pan placed on the top plate 2 and the top plate 2.

(Hot start B)
FIG. 16 is a flowchart for explaining the gap distance determination process in the first preheating step of the heating cooker according to the embodiment, and shows the operation of hot start B.

  Steps S201 to S205 in FIG. 16 are the same as steps S101 to S105 in FIG.

When the temperature difference ΔTH_1 is equal to or higher than the preset threshold value Ut ° C., that is, when the temperature of the top 2 rises above Ut ° C. during the standby time of 60 seconds (S206; Yes), It is determined that the pan is hotter than the top 2 and the H-H flag is set (S207).
In addition, when the temperature difference ΔTH_1 is equal to or less than a preset threshold value −Dt ° C., that is, when the temperature of the top board 2 decreases by Dt ° C. or more during the standby time of 60 seconds (S208; Yes), it is determined that the pan is cooler than the top 2 and the HC flag is set (S209).

  Here, in the present embodiment, as shown in FIG. 10, the threshold value Ut and threshold value -Dt in the case of hot start B are set to different values from the threshold value Ut and threshold value -Dt in the case of hot start A. . In the case of the hot start B, the threshold value Ut ° C. = 4 ° C., and the HH flag is set when the temperature TH_60s is higher than the initial top plate temperature TH_0s by 4 ° C. or more. Since the temperature of the initial top plate 2 is higher in the hot start B than the hot start A, the temperature difference between the pan and the top plate 2 when the same high temperature pan is placed on the top plate 2 is relative. This threshold value Ut is also set to a relatively small value. Further, the threshold value in the case of the hot start B is −Dt ° C. = − 10 ° C., and the HC flag is set when the temperature TH_60s is lower than the initial top plate temperature TH_0s by 10 ° C. or more. Since the temperature of the initial top plate 2 is higher in the hot start B than the hot start A, the temperature difference between the pan and the top plate when the same low temperature pan is placed on the top plate 2 is also relative. Therefore, this threshold value -Dt (absolute value) is also a relatively large value.

  In FIG. 16, if the temperature of the top 2 does not rise above Ut ° C. during the standby time of 60 seconds (S206; No) and does not drop above Dt ° C. (S208; No), H− The H flag and the HC flag are not set.

The description of FIG. 16 will be continued.
Next, the calculation unit 22 starts counting up the time counter B (S210), the control unit 23 puts 750 W into the heating coil 14 (S211), and sets the target temperature for determination of the top plate 2 to [Initial Temp. Heating for determination is performed at a plate temperature TH — 0s + 20 ° C.]. When the current temperature TH_cur of the top 2 detected by the top temperature detector 25 is equal to or higher than the determination target temperature (TH_0s + 20 ° C.) (S212; Yes), the calculation unit 22 proceeds to step S213.

  Next, the calculation unit 22 stores Time_B, which is the value of the time counter B when the temperature TH_cur of the top 2 becomes equal to or higher than the determination target temperature (TH_0s + 20 ° C.) in the storage unit 21 (S213). A temperature difference ΔTH_3 that is a difference between the target temperature (TH_0s + 20 ° C.) and the temperature TH_60s of the top plate 2 after 60 seconds of standby time is calculated (S214). This temperature difference ΔTH — 3 is the amount of temperature rise of the top plate 2 from when 750 W is started to be applied to the heating coil 14 until the top plate temperature reaches the target temperature for determination (TH — 0s + 20 ° C.).

  Next, the calculation unit 22 divides the temperature difference ΔTH_3 by Time_B, that is, determines the temperature rise amount of the top 2 from the start of the heating for determination to the target temperature for determination (TH_0s + 20 ° C.). Dividing by the time required to reach the temperature (TH — 0s + 20 ° C.), the temperature increase rate of the top 2 is calculated (S215). Next, the calculation unit 22 compares the calculated temperature rise rate of the top board 2 and the presence or absence of the H-H flag and the H-C flag with the gap distance setting table illustrated in FIG. Determination is made (S216). The calculation unit 22 stores the determined gap distance in the storage unit 21 and ends the gap distance determination process.

  On the other hand, in step S212 in FIG. 16, the temperature TH_cur of the top 2 does not reach the target temperature for determination (TH_0s + 20 ° C.) (S212; No), and the value of the time counter B has passed 200 seconds (second time limit). When it does (S217; Yes), the calculating part 22 determines that a clearance distance is the level G7 (S218), and complete | finishes the clearance distance determination process of FIG. In other words, the heating coil 14 is heated by supplying 750 W electric power, and the temperature rise amount of the top plate 2 does not reach 20 ° C. even after 200 seconds (second time limit) has elapsed. Since it is large, it is determined that the heat transmitted from the pan to the top plate 2 is small, and the gap distance is determined as G7 which is a relatively high level value. In this way, by setting an upper limit for the time to apply power to the heating coil 14 in the gap distance determination process, the pan is heated excessively during the gap distance determination process even when the gap distance is large. Can be suppressed.

  FIG. 17: is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start B of the heating cooker which concerns on embodiment. In FIG. 17, in the case of hot start B, changes in the top plate temperature and the input power to the heating coil 14 when the HC flag is set are shown.

  The initial top board temperature TH_0s is not less than the medium temperature initial threshold (80 ° C.) and less than the high temperature initial threshold (140 ° C.). During the standby time of 60 seconds from the start of the preheating process (0 s), the power supply to the heating coil 14 is stopped, the pan is not heated, and the top plate temperature is transferred by heat transfer from the pan placed on the top plate 2. Gradually decreases. Since the temperature decrease amount of the temperature TH_60s with respect to the initial top board temperature TH_0s when the standby time of 60 seconds has passed is equal to or higher than the HC flag threshold (−10 ° C.), the HC flag is set.

  Next, when power supply of 750 W is started to the heating coil 14, the pan is heated, and accordingly, the top plate temperature rises due to heat transfer from the pan, and the top plate temperature becomes the determination target temperature (TH_0s + 20 ° C. ) (That is, the amount of increase in the top temperature becomes 20 ° C. or more. Step S212 in FIG. 16; Yes). Then, the time (Time_B) from the start of heating for determination (60 s) until the top plate temperature reaches the target temperature for determination (TH_0s + 20 ° C.), and the top plate temperature from the start of heating for determination to the target temperature for determination (TH_0s + 20 ° C.) The temperature increase rate of the top 2 is calculated on the basis of the temperature increase amount until reaching. Subsequently, the gap distance is determined from the temperature increase rate and the HC flag with reference to FIG.

  As described above, in the case of the hot start B, the determination target temperature of the top temperature during the determination heating time is set by the temperature increase amount (20 ° C. in the present embodiment) with respect to the initial top temperature TH_0s. When the H-C flag is set (that is, when a pan having a temperature lower than that of the top plate 2 is placed), in the heating for determination, it has decreased to 60 seconds from the start of the preheating process (0 s). Since the temperature of the top plate 2 is increased including the temperature of the top plate 2, the heating time in the gap distance determination process can be secured. Therefore, the detection accuracy of the temperature increase rate is increased, and the determination accuracy of the gap distance determined based on the temperature increase rate can be increased.

  Although not shown, when the H-H flag is set, the temperature of the top 2 rises in 60 seconds from the start of the preheating process (0 s) as in FIG. Therefore, the amount of temperature increase during the determination heating time is smaller than when the HC flag is set. For this reason, in the condition where the H-H flag is set and the pan is likely to become high temperature, the amount of heating in the gap distance determination process can be reduced and the pan can be prevented from being heated excessively. Safety can be improved.

(Hot start C)
18 and 19 are flowcharts for explaining the gap distance determination process in the first preheating step of the heating cooker according to the embodiment, and show the operation of hot start C.

  The calculation unit 22 starts counting up the time counter A (S301). At this time, the heating coil 14 is in a power-off state (S302), the calculation unit 22 waits until the time counter A counts 60 seconds with the power off, and when 60 seconds elapse (S303; Yes), The temperature TH_60s of the top table 2 is measured and stored in the storage unit 21 (S304). Next, the calculating part 22 calculates temperature difference (DELTA) TH_1 which is the difference of the temperature TH_60s of the top plate 2 and the initial top plate temperature TH_0s after 60 seconds of standby time (S305).

  If the amount of decrease in the temperature TH_cur of the top plate 2 with respect to the initial top plate temperature TH_0s is less than 10 ° C., the calculation unit 22 continues the power OFF state (S321), and the temperature TH_cur of the top plate 2 becomes the initial top plate temperature TH_0s. If the temperature falls by 10 ° C. or more (S305; Yes), the process proceeds to step S306. Next, the calculating part 22 calculates temperature difference (DELTA) TH_1 which is the difference of the temperature TH_60s of the top plate 2 and the initial top plate temperature TH_0s after 60 seconds of standby time (S306).

  When the temperature difference ΔTH_1 is equal to or less than a preset threshold value −Dt ° C., that is, when the temperature of the top 2 is Dt during the standby time 60 seconds when the power supply to the heating coil 14 is stopped, the calculation unit 22 If the temperature has decreased by more than ° C. (S307; Yes), it is determined that the pan is cooler than the top 2 and the HC flag is set (S308).

  In this embodiment, the threshold value -Dt for the hot start C is set to a value different from the threshold values for the hot start A and B, as shown in FIG. In the case of the hot start C, the threshold value Dt ° C. = − 20 ° C., and the temperature flag TH_60s is set lower than the initial top plate temperature TH_0s by 20 ° C. or more, the HC flag is set. Since the temperature of the initial top plate 2 is higher than that of the hot start A and B, the temperature difference between the hot start C and the pan when the same low temperature pan is placed on the top plate 2 is relatively Since it increases, this threshold value -Dt (absolute value) is also set to a relatively large value.

  In FIG. 18, when the temperature of the top 2 has not decreased by Dt ° C. or more during the standby time of 60 seconds (S307; No), the HC flag is not set.

  Next, the computing unit 22 stores the top plate temperature when it is determined that the initial top plate temperature TH_0s has decreased by 10 ° C. (that is, when it is determined Yes in step S305) as the standby end temperature TH_Xs. (S309). Subsequently, the calculation unit 22 starts counting up the time counter B (S310), the control unit 23 puts 750 W into the heating coil 14 (S311), and sets the determination target temperature of the top plate 2 to [Initial Temp. Heating for determination is performed at a plate temperature TH — 0s + 10 ° C.]. When the current temperature TH_cur of the top 2 detected by the top temperature detector 25 rises by 10 ° C. or more with respect to the initial top temperature TH_0s (S312; Yes), the calculation unit 22 proceeds to step S313.

  Here, in step S212 of FIG. 16 showing the hot start B, the determination target temperature of the top plate 2 in the gap distance determination processing is increased by 20 ° C. with respect to the initial top plate temperature TH_0s. In step S312 of C, the target temperature for determination of the top plate 2 in the gap distance determination processing is increased by 10 ° C. with respect to the initial top plate temperature TH_0s, and the increase amount is smaller than that of the hot start B. This is because, in Hot Start C where the temperature of the top plate 2 in the initial stage is higher than that of Hot Start B (in this embodiment, 140 ° C. or higher), if the target temperature for determination is increased, This is because, depending on the temperature and the gap distance (for example, when the pan is hot and the gap distance is small), the pan may become excessively hot.

  Next, the computing unit 22 stores Time_B, which is the value of the time counter B when it is determined that the temperature TH_cur of the top plate 2 has increased by 10 ° C. or more from the initial top plate temperature TH_0s in the storage unit 21 (S313). ), A temperature difference ΔTH_4 that is a difference between the determination target temperature (initial top plate temperature TH_0s + 10 ° C.) and the standby end temperature TH_Xs is calculated (S314). This temperature difference ΔTH — 4 is the amount of temperature rise of the top plate 2 from when 750 W is started to be applied to the heating coil 14 until the top plate 2 reaches the target temperature for determination (initial top plate temperature TH — 0s + 10 ° C.).

  Next, the calculation unit 22 divides the temperature difference ΔTH_4 by Time_B, that is, the temperature rise of the top plate 2 from the start of heating by the heating coil 14 to the determination target temperature (initial top plate temperature TH_0s + 10 ° C.). The amount is divided by the time required to reach the target temperature for determination (initial top plate temperature TH — 0s + 10 ° C.) to calculate the rate of temperature rise of the top plate 2 (S315). Next, the calculation unit 22 determines the gap distance by comparing the calculated temperature rise rate of the top board 2 and the presence or absence of the HC flag with the gap distance setting table illustrated in FIG. 10 (S316). . The calculation unit 22 stores the determined gap distance in the storage unit 21 and ends the gap distance determination process.

  On the other hand, when the temperature TH_cur of the top plate 2 does not reach the target temperature for determination (initial top plate temperature TH_0s + 10 ° C.) in step S312 of FIG. 18 (S312; No), and the value of the time counter B has passed 150 seconds. (S317; Yes), the calculation unit 22 determines that the gap distance is G3 if the HC flag is set (S318; Yes), and does not set the HC flag (S318; No), the gap distance is determined as G7, and the gap distance determination process in FIG. 18 is terminated. In other words, when 750 W of electric power is applied to the heating coil 14 and heating is performed, and the temperature rise amount of the top 2 does not exceed 10 ° C. even after a predetermined time (150 seconds), the HC flag is set. When it is set, it is determined that it takes time to increase the temperature of the top plate 2 because the pan is cold, and the gap distance is determined as G3, which is a relatively low level value. When the HC flag is not set, it is determined that the heat transmitted from the pan to the top plate 2 is small because the gap distance is large, and the gap distance is determined as G7, which is a relatively high level value. In this way, by setting an upper limit for the time to apply power to the heating coil 14 in the gap distance determination process, the pan is heated excessively during the gap distance determination process even when the gap distance is large. Can be suppressed.

  In step S305, if the temperature TH_cur of the top plate 2 does not decrease to the initial top plate temperature TH_0s-10 ° C. (S305; No), and the value of the time counter A has passed 200 seconds (S322; Yes). Proceed to FIG. The process shown in FIG. 19 is a process executed when the amount of decrease in the temperature of the top plate 2 is less than 10 ° C. even after 200 seconds have elapsed in the heating stopped state.

  In FIG. 19, the calculation unit 22 stores the temperature TH_cur of the top 2 after 200 seconds from the start of the preheating process in the storage unit 21 as the temperature TH_200s (S323), and starts counting up the time counter C (S324). ), 750 W is input to the heating coil 14 (S325), and the target temperature for determination of the top plate 2 is set to [temperature TH_200s + 10 ° C.] to perform heating in the gap distance determination processing. When the current temperature TH_cur of the top 2 detected by the top temperature detector 25 rises by 10 ° C. or more with respect to the temperature TH_200s (S326; Yes), the arithmetic unit 22 proceeds to step S327.

  Next, the calculation unit 22 stores Time_C, which is the value of the time counter C when the temperature TH_cur of the top plate 2 is increased by 10 ° C. from the temperature TH_200s, in the storage unit 21 (S327), and the target temperature for determination ( A temperature difference ΔTH_5 that is a difference between the temperature TH_200s + 10 ° C.) and the temperature TH_200s is calculated (S328). This temperature difference ΔTH_5 is the amount of temperature rise of the top plate 2 from when 750 W is started to be applied to the heating coil 14 until the top plate 2 reaches the determination target temperature (temperature TH_200s + 10 ° C.).

  Next, the calculation unit 22 divides the temperature difference ΔTH_5 by Time_C, that is, the amount of temperature rise of the top 2 from the start of the heating for determination by the heating coil 14 to the determination target temperature (temperature TH_200s + 10 ° C.). Is divided by the time required to reach the target temperature for determination (temperature TH_200s + 10 ° C.), and the temperature increase rate of the top 2 is calculated (S329). Next, the calculation unit 22 compares the calculated rate of temperature rise of the top plate 2 with the gap distance setting table illustrated in FIG. 10 to determine the gap distance (S330). The calculation unit 22 stores the determined gap distance in the storage unit 21 and ends the gap distance determination process.

  On the other hand, when the temperature TH_cur of the top 2 does not reach the target temperature for determination (temperature TH_200s + 10 ° C.) in step S326 in FIG. 19 (S326; No), and the value of the time counter C has passed 100 seconds ( S331; Yes), the calculation unit 22 determines the gap distance to be G7, and ends the gap distance determination process of FIG. 19 (S332). That is, when heating is performed by applying 750 W to the heating coil 14 and the temperature rise of the top plate 2 does not exceed 10 ° C. even after a predetermined time (100 seconds), the gap distance is large. It is determined that the heat transmitted from the pan to the top plate 2 is small, and the gap distance is determined as G7 which is a relatively high level value. In this way, by setting an upper limit value for the time for supplying power to the heating coil 14 in the gap distance determination process (time for heating for determination), even when the gap distance is large, the gap distance determination process is in progress. It is possible to prevent the pan from being heated excessively.

  In the case of hot start C, the H-H flag is not set unlike the cases of hot start A and B described above. This is because when the pan is hotter than the top plate 2, the temperature of the top plate 2 does not drop much during the standby time, and the standby time is extended to execute the processing of FIG.

Next, the effect | action of the preheating 1st process in the case of the hot start C implement | achieved by the flowchart shown in FIG. 18, FIG. 19 is demonstrated paying attention to the temperature of the top plate 2, and the input electric power to the heating coil 14. FIG.
FIG. 20: is a time chart explaining an example of an effect | action of the preheating 1st process in the case of the hot start C of the heating cooker which concerns on embodiment. FIG. 20 shows changes in the top plate temperature and the input power to the heating coil 14 when the HC flag is set in the hot start C.

  The initial top plate temperature TH_0s is equal to or higher than the high temperature initial threshold (140 ° C.). For 60 seconds from the start of the preheating process (0 s), the power supply to the heating coil 14 is stopped and the pan is not heated, and the temperature of the top plate 2 is increased by heat transfer from the pan placed on the top plate 2. Decrease gradually. Since the temperature TH_cur of the top plate 2 when the standby time of 60 seconds elapses is 10 ° C. or more lower than the initial top plate temperature TH_0s (S305 in FIG. 18; Yes), the temperature decrease amount of the top plate 2 is ΔTH_1. Is remembered as Further, since the amount of decrease in the temperature of the top board 2 is not less than the HC flag threshold (−20 ° C.) (S307 in FIG. 18; Yes), the HC flag is set.

  Next, when power supply of 750 W is started to the heating coil 14, the pan is heated, and the temperature of the top plate 2 in contact with the pan rises due to heat transfer from the pan, and the top plate temperature is The temperature rises by 10 ° C. or more from the initial top board temperature TH_0s (S312 in FIG. 18; Yes). Then, the time (Ys−Xs = Time_B) from the start of power application to the heating coil 14 (60 s) until the top 2 reaches the determination target temperature (initial top temperature TH_0s + 10 ° C.), where Ys is the top 2 Time at which the target temperature for determination is reached, Xs is the standby end time 60 s), and temperature rise from the start of power application to the heating coil 14 (60 s) to the target temperature for determination (initial top plate temperature TH — 0s + 10 ° C.) Based on the amount (ΔTH — 4), the temperature increase rate of the top 2 is calculated. Subsequently, the gap distance is determined from the temperature increase rate and the HC flag with reference to FIG.

  FIG. 21 is a time chart for explaining another example of the operation of the preheating first step of the heating cooker according to the embodiment. 21 differs from FIG. 20 in that the temperature of the top plate 2 does not reach the target temperature for determination (initial top plate temperature TH — 0s + 10 ° C.) even after 150 seconds have passed since the power was supplied to the heating coil 14. It is. The difference from FIG. 20 will be mainly described.

When 60 seconds have passed since the start of the preheating process (0 s), the temperature of the top plate 2 is lower than the HC flag threshold value. Even after the elapse of time (210 s), the temperature of the top board 2 is less than 10 ° C. with respect to the initial top board temperature TH — 0 s (S 312 in FIG. 18; No, and S 317; Yes).
For this reason, since the HC flag is set, the gap distance is determined to be G3 by the calculation unit 22 (S318; Yes), and the gap distance determination process is terminated.

When the action shown in FIG. 21 occurs, since the temperature of the top plate 2 is lowered by 10 ° C. or more during the standby time, the pan is cooler than the top plate 2 and the gap distance is relatively long. You can see that it is small. And even if 750 W is supplied to the heating coil 14, the temperature rise rate of the top plate 2 is lower than that shown in FIG. 20, so that the cooked food in the pan is also cooler than that shown in FIG. 20. I understand.
In this case, it is conceivable to calculate the rate of temperature rise of the top plate 2 and determine the gap distance based on FIG. 11, but the top plate during heating in the gap distance determination process because the temperature of the pan is very low. When the temperature increase amount of 2 is very small, the temperature increase rate is also small, and it can be determined that the gap distance is relatively large. However, in actuality, since the gap distance is determined to be relatively small from the degree of temperature decrease of the top plate 2 during the standby time, the determination results are inconsistent. Further, no time-out restriction is provided for heating in the gap distance determination process, and the temperature rise rate is calculated by heating until the top plate 2 reaches the determination target temperature (initial top plate temperature TH — 0s + 10 ° C.) or more, and the gap distance is calculated from FIG. However, the time required for the gap distance determination process increases. Therefore, in the present embodiment, the gap distance is set to a relatively small fixed value (G3). By doing in this way, even when a pan is very low temperature, it can suppress misjudging that a gap distance is large, and can also prevent prolonged heating time of a gap distance judging process.

  Drawing 22 is a time chart explaining an example of an operation of the preheating 1st process of a cooking-by-heating machine concerning an embodiment. The difference from FIGS. 20 and 21 is that the HC flag is not set. The description will focus on the differences from FIGS.

  At the time when 60 seconds have elapsed from the start of the preheating process (0 s), the temperature of the top 2 has decreased below TH_0 s, but the amount of decrease has not reached the HC flag threshold value (FIG. 18). Step S307; No), the HC flag is not set.

  When power supply of 750 W is started to the heating coil 14 and the pan is heated, the temperature of the top plate 2 in contact with the pan rises due to heat transfer from the pan, and the temperature of the top plate 2 is The temperature rises by 10 ° C. or more from the initial top board temperature TH_0s (S312 in FIG. 18; Yes). Then, the time (Ys−60s = Time_B) until the top plate 2 reaches the target temperature for determination (initial top plate temperature TH_0s + 10 ° C.) from the start of power supply to the heating coil 14 (60 s), and the power to the heating coil 14 Based on the temperature rise amount (ΔTH_4) from the start of charging (60 s) to the determination target temperature (initial top board temperature TH_0s + 10 ° C.), the temperature rise rate of the top board 2 is calculated. Subsequently, the gap distance is determined from the temperature increase rate with reference to FIG.

The case of FIG. 22 differs from the case of FIG. 20 in that the HC flag is not set. As can be seen with reference to FIG. 11, in the range of 0.25 or more, which is a relatively large range of temperature increase, when the HC flag is present (FIG. 20), there is no HC flag (FIG. It is determined that the gap distance is smaller than 22). This is because, when the amount of temperature drop of the top plate 2 during the standby time is relatively large, it is estimated that the gap distance is relatively small and heat transfer is likely to proceed.
On the other hand, when the temperature increase rate is less than 0.25, which is a relatively small range, even when the HC flag is present (FIG. 20), the gap distance is not as large as when the HC flag is not present (FIG. 22). There is no difference in determination, and the gap distance is determined only on the basis of the rate of increase in the top plate temperature. This is because, when the gap distance is relatively large, there is a concern about excessive temperature rise of the pan due to heating, so do not underestimate the gap distance and make the gap distance more inclined to the safe side. This is because it is judged.

  Drawing 23 is a time chart explaining an example of an operation of the preheating 1st process of a cooking-by-heating machine concerning an embodiment. FIG. 23 differs from FIGS. 20 to 22 in that the amount of decrease from the initial top temperature TH_0s of the top 2 has not reached 10 ° C. even after the standby time has elapsed (60 s). The description will focus on the differences from FIGS.

  When the standby time of 60 seconds elapses, the temperature of the top plate 2 is lower than the initial top plate temperature TH_0s, but the amount of decrease has not reached 10 ° C. (step S305 in FIG. 18; No). The waiting time is extended. Then, when the temperature of the top plate 2 decreases by 10 ° C. or more from the initial top plate temperature TH_0s during the extended standby time (step S305 in FIG. 18; Yes), the standby time ends. However, since the difference between the temperature TH_60s at the time of 60 seconds and the initial top board temperature TH_0s is less than the HC flag threshold, the HC flag is not set (step S307 in FIG. 18; No).

  Subsequently, when the heating coil 14 is started to be charged with 750 W and the pan is heated, the top plate 2 in contact with the pan also rises in temperature due to heat transfer from the pan, and the top plate 2 The temperature becomes equal to or higher than the determination target temperature (initial top plate temperature TH — 0s + 10 ° C.) (S312 in FIG. 18; Yes). Then, the time (Ys−Xs = Time_B) until the top plate 2 reaches the target temperature for determination (initial top plate temperature TH_0s + 10 ° C.) from the start of power supply to the heating coil 14 (Xs), and the power to the heating coil 14 Based on the temperature rise amount (ΔTH_4) from the start of charging (Xs) to the target temperature for determination (initial top board temperature TH_0s + 10 ° C.), the temperature rise rate of the top board 2 is calculated. Subsequently, the gap distance is determined from the temperature increase rate and the HC flag with reference to FIG.

  In the case of FIG. 23, since the amount of temperature drop of the top plate 2 during the standby time of 60 seconds is relatively small, the standby time is extended to wait for the temperature of the top plate 2 to drop. In this way, waiting for the temperature of the top plate 2 to drop is that if the heating for the gap distance determination process is performed while the top plate 2 is in a high temperature state, the temperature of the top plate 2 is not easily increased. This is because there is a possibility that the calculation accuracy of the increase rate may be lowered, and as a result, the determination accuracy of the gap distance may be lowered. For this reason, after waiting for the temperature fall of the top plate 2, the heating for a clearance distance determination process is performed. By doing in this way, even when the top plate 2 and the pan are in a high temperature state and start of preheating is instructed, the accuracy of determining the gap distance can be ensured.

  FIG. 24 is a time chart for explaining an example of the action of the first preheating step of the heating cooker according to the embodiment. The difference from FIG. 23 is that the amount of decrease from the initial top plate temperature TH_0s of the top plate 2 does not reach 10 ° C. even when the standby time is extended to 200 seconds. The difference from FIG. 23 will be mainly described.

  When 60 seconds have passed since the start of the preheating process (0 s), the temperature of the top plate 2 is lower than the initial top plate temperature TH_0s, but the amount of decrease has not reached 10 ° C. (FIG. 18). Step S305; No), the standby time is extended. And even if 200 seconds have passed since the standby time was extended and the preheating process started (0 s), the amount of decrease in the temperature of the top plate 2 has not yet reached 10 ° C. (step S322 in FIG. 18; Yes). However, the waiting time ends at 200 seconds.

  Subsequently, 750 W of power is started to be applied to the heating coil 14. Then, the pan is heated, and accordingly, the top plate 2 in contact with the pan also rises in temperature due to heat transfer from the pan, and the temperature of the top plate 2 is higher than the temperature TH_200s at the start of power supply (200 s). The temperature rises by 10 ° C. or more (S326 in FIG. 19; Yes). Then, based on the time (Xs−200 s) from the start of power application to the heating coil 14 (200 s) until the top 2 reaches the target temperature for determination (temperature TH_200 s + 10 ° C.) and the temperature difference ΔTH_5 (10 ° C.). The temperature rise rate of the top plate 2 is calculated. Subsequently, the gap distance is determined from the temperature increase rate with reference to FIG.

  In the case of FIG. 24, even if the extended standby time of 200 seconds elapses, the amount of decrease in the temperature of the top plate 2 does not reach 10 ° C., so the standby is completed at the time of 200 seconds. The fact that the temperature of the top plate 2 is difficult to decrease means that the temperature of the pan is high and it can be determined that the heat transfer from the pan to the top plate 2 is good, so it is estimated that the gap distance is relatively small. By providing a time-out limit (200 seconds) in the extension time of the standby time, the preheating first process is prevented from becoming too long.

  FIG. 25 is a time chart for explaining an example of the action of the first preheating step of the heating cooker according to the embodiment. The difference from FIG. 24 is that the temperature of the top plate 2 does not reach the target temperature for determination (temperature TH_200s + 10 ° C.) even after 100 seconds have passed since the power was supplied to the heating coil 14. The difference from FIG. 24 will be mainly described.

Even when 100 seconds have elapsed after applying 750 W of power to the heating coil 14 (300 s), the temperature of the top 2 is less than 10 ° C. with respect to the temperature TH_200 s at the start of power application (step S326 in FIG. 19). No, step S331; Yes).
In this case, the gap distance is determined by G7, which is a relatively large value among the assumed gap distances, and the calculation unit 22.

When the action as shown in FIG. 25 occurs, the temperature of the top plate 2 is not easily lowered even if the standby time is extended, and the temperature of the top plate 2 rises even when power is applied to the heating coil 14. Since it is difficult, it is estimated that the heat transfer between the top plate 2 and the pan is difficult to proceed, that is, the gap distance is large. For this reason, in this embodiment, the gap distance is determined as G7, which is a relatively large value.
For example, it is conceivable to calculate the temperature increase rate of the top plate 2 and determine the gap distance based on FIG. 11, but in such a case, since the temperature increase amount of the pan is small, the determination accuracy of the temperature increase rate deteriorates. there is a possibility. If the gap distance determined based on the rate of temperature rise is erroneously determined to be smaller than the actual value, the temperature of the pot detected based on the gap distance will also be incorrect, and when the pot is heated, Temperature can rise excessively. Therefore, in the present embodiment, the gap distance inclined to the safer side is determined by setting the gap distance to a relatively large fixed value (G7).

  As described above, when the initial top temperature TH_0s is equal to or higher than the initial threshold (40 ° C.), the determination heating is performed with a constant heating power so as to reach the determination target temperature determined according to the initial top temperature TH_0s. And the gap distance is determined based on the result.

Here, in step S112 of FIG. 9 showing the hot start A, the determination target temperature is set to 100 ° C. (absolute value), whereas in step S212 of the hot start B, the top plate 2 in the gap distance determination process is set. The target temperature for determination was the amount of increase with respect to the initial top board temperature TH_0s. This is because the target temperature for determination is set to an absolute value in the hot start B in which the temperature of the top 2 is higher than that in the hot start A (in this embodiment, 80 ° C. or higher and lower than 140 ° C.). Then, depending on the temperature of the pan and the gap distance (for example, when the pan is hot and the gap distance is small), the time until the top 2 reaches the target temperature for determination is too short, and the gap distance cannot be determined accurately. This is because there is a possibility.
On the other hand, in the hot start A where the top plate 2 starts preheating from a relatively low temperature state (40 ° C. or more and less than 80 ° C. in the present embodiment), the gap distance determination processing is performed by setting the determination target temperature to 100 ° C. The heating time is ensured so that the gap distance can be accurately determined.

Further, also in the hot start C where the initial top plate temperature is the highest in the present embodiment, for the same reason, the determination target temperature of the top plate 2 in step S312 of FIG. 18 is set to the initial top plate temperature TH_0s. The amount of increase relative to
Further, in the case of the hot start C, in step S326 of FIG. 19 executed when the temperature drop amount of the top plate 2 is less than 10 ° C. even after the standby time (including the extended standby time) has elapsed, The target temperature for determination of the plate 2 is not the initial top plate temperature TH_0s but the amount of increase with respect to the temperature TH_200s after the standby time. When the amount of decrease in the top plate temperature during the waiting time is small, the gap distance is large or the temperature of the pan is high. By setting the amount of temperature increase with respect to the temperature TH_200s after the standby time, when the temperature of the top plate 2 is decreasing while being less than 10 ° C. during the standby time, the top plate is included in the clearance distance determination process including the decrease. Since the temperature is increased, the heating time can be secured, and the detection accuracy of the temperature increase rate can be increased. In addition, when the gap distance is large or when the temperature of the top plate 2 is high, the heating time in the gap distance determination process is relatively short, so that excessive heating of the pan and the cooked product is suppressed, and cooking is performed. The safety of the vessel can be increased.

  The time limit for heating for determination is set to be shorter in the order of hot start A, B, and C. This is because, when the initial top plate temperature is relatively high, if the heating is performed for a long time, the temperature of the pan becomes excessively high. When the initial top plate temperature is high, safety can be further improved by shortening the time limit for heating for determination as compared with the case of low temperature. Regardless of the present embodiment, even if the initial top plate temperature is different, the time limit for heating for determination may be the same time.

(cold start)
The gap distance determination process when the temperature of the top plate 2 is relatively low (less than the low temperature initial threshold of 40 ° C. in the present embodiment) (cold start) will be described.
In the case of a cold start, a standby time is not provided as in the hot start A to C, and when a preheating start instruction is input, a constant power supply to the heating coil 14 is started.
When a predetermined time (for example, 50 seconds) elapses from the start of heating, the calculation unit 22 sets the initial top plate temperature TH_0s of the top plate 2 before starting to apply power to the heating coil 14 and the top plate 2 at the time of 50 seconds. The temperature difference ΔTH_6 with the temperature TH_50s is compared with the cold start clearance distance setting table shown in FIG. 26 to determine the clearance distance. The cold start gap distance setting table shown in FIG. 26 is a table in which the temperature difference ΔTH — 6 at the start of power application to the heating coil 14 and a predetermined time (50 seconds) after the start of power application is associated with the level of the gap distance. It is. The gap distance level table is a table of values obtained through experiments or the like, and is stored in the storage unit 21 in advance. In the present embodiment, the amount of floating of the pan (gap distance) is divided into eight stages from levels G1 to G8.

(Preheating second process)
Next, the preheating second step performed subsequent to the above-described preheating first step will be described.
FIG. 27 is a flowchart illustrating a second preheating step of the heating cooker according to the embodiment.

  As shown in FIG. 27, the control unit 23 inputs 1.5 kW of power to the heating coil 14 (S401). Next, the calculation unit 22 stores the temperature (infrared sensor temperature) detected by the infrared temperature detection unit 24 at this time as IR_H0 in the storage unit 21, and starts a timer counter (S402).

  When a predetermined emissivity detection time (30 seconds in the embodiment) elapses (S403; Yes), the calculation unit 22 stores the infrared sensor temperature at this time in the storage unit 21 as IR_H30 (S404).

The computing unit 22 calculates a difference ΔT_IR that is a difference value between IR_H30 and IR_H0 (S405).
Next, the calculation unit 22 calculates the difference value ΔIR between IR_H30 and IR_H30 calculated in step S405 (that is, the increased value from the start of heating to 30 seconds) and the gap distance determined in the first preheating step. An emissivity estimation process for estimating the emissivity of the pan in comparison with the emissivity setting table shown in FIG. 28 is performed (S406). Since the influence of the infrared rays from the top plate 2 is different according to the gap distance of the pan, the threshold value for estimating the emissivity is different depending on the gap distance level of the pot, as shown in FIG. . For example, when the gap distance is level G1, the emissivity of the pan is estimated by comparing ΔT_IR calculated in step S405 with the ΔIR threshold (40 ° C.) corresponding to level G1. The table shown in FIG. 28 is a table of values obtained through experiments or the like, and is stored in the storage unit 21 in advance.

  Next, the calculation unit 22 refers to the correction coefficient table of FIG. 29 based on the gap distance determined in the first preheating step and the emissivity of the pan bottom determined in step S406, and calculates the correction coefficients α and β. Determine (S407). The correction coefficient table shown in FIG. 29 is a table in which a combination of the gap distance (G1 to G8) and the emissivity, a correction coefficient α (first correction coefficient), and a correction coefficient β (second correction coefficient) are combined. Are stored in the storage unit 21 in advance.

Next, the calculation unit 22 estimates the temperature of the pan placed on the top 2 using the following equation (1) using the correction coefficients α and β determined in step S407 ( S408).
Estimated temperature of the pan Tn = α × IR−β × TH (1)
However, the code | symbol of Formula (1) is as follows.
IR: Output value TH of infrared temperature detector 24 TH: Output value of top plate temperature detector 25 α: first correction coefficient β: second correction coefficient

  As shown in Expression (1), in the present embodiment, the output value of the infrared temperature detection unit 24 is multiplied by a correction coefficient α (first correction coefficient) to obtain an infrared temperature correction value. The output value of the detection unit 25 is multiplied by a correction coefficient β (second correction coefficient), and this is used as the top temperature correction value. And the estimated temperature value Tn of the pan is obtained by subtracting the top plate temperature correction value from the infrared temperature correction value.

Conventionally, the infrared energy radiated from the pan detected by the infrared sensor 12 and transmitted through the top plate 2 and the infrared energy radiated from the top plate 2 obtained by the top plate temperature detector 25 from the infrared energy radiated from the top plate 2. The energy calculation when subtracting the energy required a multiplication of the fourth power and the emissivity with respect to the output temperature as derived from the Stefan-Boltzmann equation.
However, the calculation of the fourth power by the calculation unit 22 such as a microcomputer increases the load. In this embodiment, the simplified formula (1) obtained from the experimental results is used.

  As shown in FIG. 28, in the case of the same emissivity, when the gap distance is large, the correction coefficient β (second correction coefficient) is a smaller value than when the gap distance is small. This indicates that the larger the gap between the pan bottom and the top plate 2, the larger the temperature difference between the pan bottom and the top plate 2 when the temperature is stabilized, and the smaller the proportion of infrared rays emitted from the top plate 2 is. . Accordingly, the larger the gap distance is, the smaller the correction coefficient β applied to the output value of the top plate temperature detection unit 25 is reduced, thereby reducing the amount of subtracting the influence of the top plate 2 when calculating the pan temperature estimated value Tn. Yes. When the gap distance is large, the same effect can be obtained by increasing the correction coefficient α instead of decreasing the correction coefficient β as compared with the case where the gap distance is small.

  As shown in FIG. 28, when the gap distance level is the same, when the emissivity is low, the correction coefficient α (first correction coefficient) is larger than when the emissivity is high. This is because the lower the emissivity, the smaller the infrared energy radiated from the bottom of the pan, the smaller the amount of infrared light transmitted through the top plate 2, and the need for amplification correction. For the same reason, when the gap distance level is the same, the correction coefficient β (second correction coefficient) is smaller when the emissivity is low than when it is high. By doing in this way, the amount which deducts the influence part of the top plate 2 in calculating the temperature estimated value Tn of a pan is reduced.

As described above, the correction coefficient α determined based on the determined gap distance and emissivity is multiplied by the output value of the infrared temperature detection unit 24, and the correction coefficient β is multiplied by the output value of the top plate temperature detection unit 25. By performing the calculation, it is possible to estimate the temperature of the pan bottom.
Although not shown, the calculation unit 22 performs a process of calculating the pan temperature estimated value Tn using the correction coefficients α and β determined in step S407 and the above-described equation (1) at a predetermined cycle thereafter. .

  Next, the calculation unit 22 determines whether or not the estimated temperature value Tn of the pan bottom calculated in step S408 has reached a set temperature (for example, 180 ° C.) (S409). And the calculating part 22 complete | finishes a preheating process, when the temperature estimated value Tn of a pan bottom reaches preset temperature (S409; Yes).

  On the other hand, when the estimated temperature value Tn of the pot bottom has not reached the set temperature (S409; No), the calculation unit 22 determines that the estimated temperature value Tn of the pot is 130 ° C lower by 50 ° C than the set temperature (180 ° C). Is reached (S410), and when it is reached, the heating power is reduced to 1.25 kW (S411). Next, the calculation unit 22 determines whether the estimated temperature value Tn of the pan has reached 150 ° C., which is 30 ° C. lower than the set temperature (180 ° C.) (S412). (S413). Next, the calculation unit 22 determines whether the estimated temperature value Tn of the pan has reached 170 ° C. at a value 10 ° C. lower than the set temperature (180 ° C.) (S414). It is reduced to .8 kW (S415). When the estimated temperature value Tn of the pan reaches the set temperature (180 ° C.) (S416; Yes), the calculation unit 22 ends the preheating second step. Although the specific numerical value illustrated in FIG. 27 is an example, when the thermal power is gradually reduced as the temperature estimated value Tn approaches the set temperature in a predetermined cycle as described above (S410 to S416), so-called overshoot is generated. It is possible to suppress the temperature of the food in the pan to the preheating target temperature.

  As described above, in the present embodiment, utilizing the fact that the rate of increase in the temperature of the top plate 2 when the heating means heats the pan becomes smaller as the gap distance between the surface of the top plate 2 and the pan bottom increases, The gap distance was determined. Then, when the heating means performs heating to calculate the rate of temperature rise of the top plate 2, if the top plate temperature before the start of heating is equal to or higher than the initial threshold, the top plate temperature before the start of heating depends on the top plate temperature before the start of heating. Heating was performed at a constant power so that the top plate temperature reached the set eye determination standard temperature. For this reason, when the initial top plate temperature is relatively low, the determination target temperature is set so that the temperature increase width until reaching the determination target temperature is increased, thereby improving the calculation accuracy of the temperature increase rate. In addition, when the initial top plate temperature is relatively high, the temperature increase rate is measured by setting the target temperature for determination so that the temperature increase width until reaching the target temperature for determination becomes small. Therefore, it is possible to prevent the food in the pan from becoming hot during heating. Therefore, it is possible to detect the gap distance while balancing the improvement in the accuracy of detecting the gap distance and the suppression of the high temperature of the food in the pan.

For example, if heating is performed at a constant power for a certain period of time in order to calculate the temperature rise rate of the top panel 2, if the top panel temperature before the start of heating is in a high temperature state, the slope of the temperature increase within a certain period of time is Relatively small. For this reason, when the top plate temperature before the start of heating is in a high temperature state, an erroneous determination of the temperature increase rate is relatively likely to occur, and an error is easily generated in the determination of the gap distance based on the temperature increase rate. On the other hand, if, for example, the heating time is increased in order to increase the slope of the temperature rise, there is a risk that the cooking such as oil in the pan becomes hot during the heating for measuring the temperature rise rate.
However, as described above, in the present embodiment, if the top plate temperature before the start of heating is equal to or higher than the initial threshold value, a determination target temperature is determined according to the top plate temperature before the start of heating, and the top plate temperature is determined by the top plate temperature. It was made to heat at a constant heating power so as to reach the target temperature. For this reason, when the top plate temperature before the start of heating is equal to or higher than the initial threshold value, the temperature increase rate is determined by setting the target temperature for determination so that the temperature increase range becomes large when the top plate temperature before the start of heating is low. Heating for measuring the rate of temperature rise is possible by setting the target temperature for determination so that the temperature rise width is small when the top plate temperature before the start of heating is high. It is possible to prevent the food in the pan from becoming hot. Thus, according to the present embodiment, for example, even when cooking is performed on the top plate 2 and the top plate 2 is continuously heated in a hot state, the detection accuracy of the gap distance is improved, It is possible to obtain a heating cooker that balances the suppression of the high temperature of the food in the pan.

  In the present embodiment, predetermined time limits (the first time limit, the second time limit, and the third time limit) have elapsed during heating for measuring the rate of temperature rise of the top 2. However, if the target temperature for determination is not reached, it is determined that the gap distance is large, and heating for measuring the temperature increase rate is terminated. For this reason, since it can suppress that the foodstuff in a pan becomes high temperature too much when clearance gap distance is large, safety | security can be improved.

  Moreover, in this Embodiment, before starting the heating for measuring the temperature rise rate of the top plate 2, the waiting time which does not heat was provided. And based on the change of the top plate temperature during the standby time, the level of the temperature between the top plate 2 and the pan placed on the top plate 2 is determined, and when the pan is higher than the top plate temperature, The gap distance is corrected so that the gap distance calculated based on the rate of temperature rise is larger than that when the pan is at a lower temperature than the top plate temperature. For example, when the placed pan is hot and the gap distance is large, it is determined that the gap distance is small because the temperature rise rate of the top plate 2 is relatively small even though the gap distance is actually large. If this happens, the temperature of the pan detected based on the gap distance is detected to be lower than the actual value, and as a result, the food in the pan may become excessively hot. However, in this embodiment, if the temperature rise is the same amount, when the pan temperature is higher than the top plate temperature, the gap distance is determined to be larger than when the temperature is low. It is possible to suppress erroneous determination that underestimates the gap distance, and to perform heating control with high accuracy. Moreover, since the excessive temperature rise of a pan can be suppressed, the safety | security of a heating cooker can be improved.

  Moreover, in this Embodiment, in the state in which the pan was mounted on the top plate 2, the gap distance between the pan bottom and the top plate 2 is determined, and the emissivity of the pan is estimated by taking the gap distance into account. I made it. Then, correction coefficients α and β are selected based on the gap distance between the pan bottom and the top plate 2 and the emissivity of the pan, and the output value of the infrared temperature detector 24 and the top plate temperature are selected based on the correction coefficients α and β. The temperature of the pan bottom is detected by correcting the output value of the detection unit 25 and subtracting the corrected temperature of the top plate temperature detection unit 25 from the corrected temperature of the infrared temperature detection unit 24. For this reason, even when the pan placed on the top 2 is floating or warped, the temperature of the pan bottom can be detected with high accuracy. Since it is possible to control the energization of the high-frequency power to the heating coil 14 based on the accurate temperature information detected in this way, it is possible to obtain a cooking device capable of suppressing wasteful heating and insufficient heating. it can.

  In addition, the specific numerical values, such as temperature and time illustrated in each figure, are examples, and arbitrary values can be adopted without departing from the gist of the invention. Moreover, in the said embodiment, when the top plate temperature before a heating start is more than an initial threshold value (40 degreeC), it classify | categorizes into three types of hot start A, B, and C based on an initial top plate temperature, and operate | moves. However, if the initial top board temperature is equal to or higher than the initial threshold value, no further classification is required.

  Moreover, although the case where fried food cooking is performed was demonstrated in the said description as an example, the same process is performed also when performing the cooking menu which performs the heating control which maintains the temperature of to-be-heated objects other than fried food at preset temperature. be able to. Moreover, also when setting only a thermal power without setting a cooking menu and heating, the above-mentioned clearance distance determination process, emissivity determination process, and to-be-heated object temperature detection process can be performed.

  DESCRIPTION OF SYMBOLS 1 Main body, 2 Top plate, 3 Operation part, 4 Display part, 5 Thermal-power display part, 6 Heating port, 7 Transmission window part, 8 Exhaust port, 9 Intake port, 9a Intake port, 10 High temperature display part, 12 Infrared sensor, DESCRIPTION OF SYMBOLS 13 Coating, 14 Heating coil, 14a Inner heating coil, 14b Outer heating coil, 15 Gap, 16 Heating coil support part, 17 Contact type temperature sensor, 18 Sensor case, 21 Memory | storage part, 22 Computation part, 23 Control part, 24 Infrared Temperature detection part, 25 Top plate temperature detection part, 26 High frequency inverter, 31 Thermal power setting key, 32 Menu key, 100 Heating cooker, 200 pan.

Claims (4)

A top plate on which the object to be heated is placed;
Heating means disposed under the top plate;
A top plate temperature detecting means for detecting the temperature of the top plate;
Based on the detection result of the top plate temperature detection unit, a gap distance determination unit that determines a gap distance between the bottom surface of the heated object placed on the top plate and the surface of the top plate;
When the initial top plate temperature, which is the top plate temperature before the heating unit starts heating, is equal to or higher than the initial threshold, heating of the heating unit is stopped until the top plate temperature is lowered by a predetermined temperature. And a control unit that causes the gap distance determining means to start determining the gap distance when the top plate temperature is lowered by a predetermined temperature. The controller is
The cooking device according to claim 1, wherein when the standby time for continuing to stop the heating of the heating means has elapsed for a predetermined time, the gap distance determining means starts the determination of the gap distance. . The gap distance determining means includes
When the initial top temperature is equal to or higher than the initial threshold,
The top plate temperature rise rate when the heating means performs heating for determination in which the heating means heats with a constant heating power so that the top plate temperature reaches a target temperature for determination determined based on the initial top plate temperature, and preset. The cooking device according to claim 1 or 2, wherein the gap distance is determined based on a correspondence relationship between the top plate temperature rise rate and the gap distance. The controller is
The cooking device according to claim 3, wherein the determination heating time is shortened as the initial top plate temperature is higher.

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