JP5865010B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker including temperature detection means for detecting the temperature of a pan placed on a top plate via the top plate.

  Conventionally, in this type of induction heating cooker, a patent document that detects the temperature of a pan placed on a top plate by a temperature detector (temperature sensor) composed of a thermistor provided in close contact with the lower surface of the top plate There is an induction heating cooker according to 1.

JP 2009-26571 A

  However, in the induction heating cooker of the above-mentioned prior art, the path for detecting the temperature of the pan of the temperature detector composed of the thermistor provided in close contact with the lower surface of the top plate is the pan bottom of the pan, the recess of the pan bottom. Heat is transmitted to the space and the top plate, and the temperature of the pan is detected by heat conduction. The temperature to be detected is the difference between the pans used, especially when the bottom of the pan is concave (indented) If it is flat or convex on the opposite side (outside), an error may occur, so ask the user for a pot that can be used. The tempura hot pot required for cooking was sold in the package of the induction heating cooker as an accessory, and cooking of fried foods other than the supplied tempura hot pot was prohibited.

The present invention has been made to solve the above-described problem, and includes a top plate on which a pan is placed, a heating coil provided below the top plate, and the pan provided below the top plate. and infrared sensor pan bottom of you detect the temperature of the pan bottom and receives the infrared light radiated by the thermistors for detecting the temperature of pan bottom of the pan through the top plate is provided below the top plate, the heating Inverter means for supplying electric power to the coil, an operation unit for setting a preset temperature for heating the pan, and the inverter means are controlled so that the temperature of the pan becomes the preset temperature using the infrared sensor or the thermistor. Control means for controlling the temperature of the pan, and the control means adjusts the temperature of the pan with the infrared sensor when cooking the fried food, and detects the infrared sensor. Degrees a predetermined time has only reached the control temperature, further, if the detected temperature of the thermistor continues for a predetermined time in succession state to remain in a change in a certain temperature range, the detected temperature of the thermistor The inverter means is controlled by comparing with the detected temperature of the thermistor and the changed control temperature as the control temperature used when cooking the detected temperature detected stably and determining the stable temperature.

  According to the induction heating cooker of the present invention, it is possible to accurately detect the temperature of the pan using a temperature sensor configured by a thermistor provided in close contact with the lower surface of the top plate.

The external appearance perspective view of the induction heating cooking appliance of one Example. The top view except the top plate of the induction heating cooking appliance of one Example. The block diagram which mainly made the right and left heating coils of the induction heating cooking appliance of one Example. The figure explaining a reflection type photo interrupter. The figure explaining the upper surface operation part and upper surface display part of the induction heating cooking appliance of one Example. The block diagram of the inverter means of the induction heating cooking appliance of one Example. The flowchart explaining operation | movement of the induction heating cooking appliance of one Example.

  An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is an external perspective view of the induction heating cooker according to the first embodiment. In FIG. 1, the top plate 2 is horizontally arrange | positioned on the upper surface of the main body 1 of the induction heating cooking appliance. The top plate 2 is made of crystallized glass with a high heat resistance and has a thickness of about 4 mm, and the pan 30 is placed thereon. Below the top plate 2, the annular heating coils 3 are arranged on the left and right sides of the upper part in the main body 1 and the central rear part, respectively, and the induction heating is performed on the pan 30 and the like placed on the top plate 2. On the front side upper surface of the top plate 2, upper surface operation units 7 a, 7 b, 7 c (operation unit 7) are provided as operation units for setting the heating conditions of the pot 30 corresponding to each heating coil 3. 3 is set for energization. Corresponding to the upper surface operation parts 7a, 7b and 7c, upper surface display parts 8a, 8b and 8c are provided in the vicinity of the upper surface operation parts 7a, 7b and 7c, and the energization state of each heating coil 3 is determined. indicate. The upper surface operation unit 7a inputs the heating power of the heating coil 3 on the right side of the main body 1, the upper surface operation unit 7b inputs the heating power of the heating coil 3 at the center rear of the main body 1, and the upper surface operation unit 7c is on the left side of the main body 1. The heating power of the heating coil 3 is input.

  An intake port 4 that opens upward is provided on the right side of the rear portion of the main body 1, and cooling air sucked from the intake port 4 by a fan (not shown) provided in the main body 1 is introduced into the main body 1. It cools by flowing in the control board (not shown), the heating coil 3, etc. which were provided. An exhaust port 5 for exhausting the cooling air that has cooled the inside of the main body 1 is provided on the rear left side of the main body 1.

  A grill heating means 6 for grilling fish, pizza or the like is provided on the left side of the front surface of the main body 1, and the grill heating means 6 has a box shape with an open front, and a sheathed heater or the like in an internal cooking chamber. The thermistor for detecting the temperature of the heating element and the internal temperature are provided, and the front surface is closed by a grill door 6b to which a handle 6a is attached. The grill door 6b has a saucer attached to the back side of the grill door 6b. The grill door 6b is housed in a cooking chamber so that it can be inserted and removed freely from the front opening. To do.

  A main power switch 9 for supplying power to the main body 1 and a front operation unit 10 for inputting cooking conditions for the grill heating means 6 and the like are provided on the right front portion of the main body 1. The front operation unit 10 has a so-called kangaroo pocket shape in which the upper part of the operation panel 11 is tilted to the front side around a rotation axis provided below and the operation keys 12 are exposed upward.

  FIG. 2 is a top view of the induction heating cooker excluding the top plate 2, and FIG. 3 is a block diagram showing a configuration mainly including the left and right heating coils 3 of the induction heating cooker.

  As shown in FIG. 2, the heating coils 3 arranged on the left and right and the central rear part are respectively an annular inner heating coil 3a and an annular outer heating coil 3c arranged with an annular gap 3b on the outside thereof. It consists of The reason why the gap 3b is provided in the heating coil 3 is to disperse the magnetic flux generated by the inner heating coil 3a and the outer heating coil 3c and to make the temperature of the pan 30 uniform. In addition, although each heating coil 3 was set as the structure which provides the clearance gap 3b, it is not limited to this in particular. For example, the structure which is set as the heating coil 3 without the gap | interval 3b which wound the inner side heating coil 3a and the outer side heating coil 3c without the gap may be sufficient.

  As shown in FIG. 3, the heating coil 3 is installed on a coil base 13. A gap spacer 14 is provided at appropriate intervals from the outer periphery of the coil base 13 toward the center by a support member 16 attached to the outer peripheral edge of the coil base 13, and the coil base 13 includes a plurality of coil bases 13. By being biased in the direction of the top plate 2 by a spring (not shown), the heating coil 3 is substantially parallel to the top plate 2, and the pot 30 and the heating coil 3 placed on the top plate 2 are The gap is kept constant. The heating coil 3 employs a litz wire to suppress the skin effect, and a voltage of several hundred volts is applied at a high frequency of several tens kHz by the inverter means 100 described later, and a high frequency magnetic field is applied to the pan 30. An eddy current is generated in the pan 30 and the pan 30 is heated by self-heating.

  An inner temperature sensor 15a of a plurality of temperature sensors 15 composed of thermistors is provided in close contact with the lower surface of the top plate 2 in the vicinity of the center of the heating coil 3 disposed on the left and right. The temperature of the pan 30 placed above is detected via the top plate 2 (by heat conduction).

  Similarly, the gap 3b of the heating coil 3 is provided with outer temperature sensors 15b, 15c, 15d composed of thermistors at equal distances from the center of the heating coil 3 and at equal intervals of 120 degrees. 15b, 15c, and 15d are provided on the gap spacer 14 as a cushioning material (not shown) and are in close contact with the lower surface of the top plate 2, thereby detecting the temperature of the pan 30 placed above the heating coil 3. The temperature sensor 15 composed of a thermistor detects the temperature transmitted by heat conduction and changes its resistance, and the temperature and resistance value confirmed in advance by capturing the resistance change by the control means 118 described later. From the relationship, the temperature detected by the temperature sensor 15 is calculated.

  Below the gap 3b of the heating coil 3 arranged on the left and right, an infrared sensor 17 is provided that receives infrared rays emitted from the bottom surface of the pan 30 through the top plate 2 and detects the temperature from the received infrared energy. It has been. The infrared sensor 17 is a temperature sensor using a thermal detection element, and its light receiving surface 17a is located at a position near the center of the inner heating coil 3a and about 35 mm from the lower surface of the top plate 2 below the heating coil 3. It is provided at a remote location. Then, a voltage corresponding to the amount of received infrared light is output, and the control means 118 (to be described later) amplifies the output voltage and determines the detected temperature of the infrared sensor 17 from the relationship between the voltage amount and the temperature confirmed in advance. Is to be calculated. Further, the light receiving surface 17a is provided with a lens, a light guide tube, and the like (not shown) that limit the viewing angle of infrared rays to be detected. As shown in FIG. The viewing angle is detected by the detection spot 17b.

  A reflective photo interrupter 18 is provided at a position away from the lower surface of the top plate 2 in the gap 3b between the heating coils 3 arranged on the left and right. FIG. 4 is a diagram for explaining the reflective photointerrupter 18. As shown in the drawing, the reflection type photointerrupter 18 has an infrared LED 18a as an infrared light emitting means and an infrared phototransistor 18b as an infrared light receiving means arranged on the same plastic member and molded 18c. A plastic lens is formed on the light emitting surface of the infrared LED 18a, and irradiates a thin beam of infrared light upward. A visible light blocking plastic lens is formed on the light receiving surface of the infrared phototransistor 18b, and the reflected infrared light at the object (pan bottom) of the irradiated infrared light is received with a narrow viewing angle, and the amount of received light. A current proportional to is output. Here, the reflection type photo interrupter 18 is provided at a position away from the infrared sensor 17, but the reflection type photo interrupter 18 and the infrared sensor 17 may be provided close to each other, and they are installed in an integrated package. May be.

  From the output of the infrared phototransistor 18 b of the reflection type photointerrupter 18, the reflectance of the bottom surface of the pan 30 placed on the top plate 2 is measured by the reflectance measuring means 19 and input to the control means 118. The control means 118 calculates the temperature of the pan 30 by correcting the value output from the infrared sensor 17 using this reflectance.

  FIG. 5 is a diagram illustrating the upper surface operation unit 7a and the upper surface display unit 8a. Since the contents of the upper surface operation unit 7c and the upper surface display unit 8c are the same as the contents of the upper surface operation unit 7a and the upper surface display unit 8a, the description thereof is omitted. The upper surface display unit 8a is divided into a display unit 81a and a display unit 81b, and the display unit 81a displays the thermal power input by the thermal power setting means 72, the cooking menu input by the menu setting means 71, and the like. The display unit 81b informs the user of the timing of loading the ingredients when the pan 30 is preheated and the temperature of the pan 30 reaches an appropriate temperature in the “fried food” or “steak” menu set by the menu setting means 71. “Preheating” and “Appropriate temperature” can be displayed so as to be able to. The thermal power that can be set by the thermal power setting means 72 is divided into four stages: a “hot fire” key 72a, a “low fire” key 72b, a “medium fire” key 72c, and a “high fire” key 72d. Keys are provided individually according to the thermal power so that you can. The arrow adjusting means 73 is used to finely adjust the medium heat up and down after setting the medium power with the heat power that cannot be input by the heat power setting means 72, for example, with the "medium heat" key 72c.

  The menu setting means 71 is for setting “cooking rice”, “fried food”, “boiled water”, “stir fried food”, “steak”, etc. for automatic cooking. A menu is displayed at 81a, and the menu is switched and displayed each time the menu setting means 71 is pressed. This selects the menu to be used. When “fried food” is selected by the menu setting means 71, it is necessary to set the oil temperature next. In this case, the arrow adjusting means 73 is operated to set six set temperatures from 150 ° C. to 200 ° C. it can. For example, when fried food is set by the menu setting means 71 and then the oil temperature is set to 180 ° C. by the arrow adjusting means 73, the display unit 81a displays the number “180” and “fried food” as shown in FIG. Is displayed. Reference numeral 74 denotes a cut / start key for starting or stopping cooking.

  FIG. 6 is a block diagram of the inverter means 100. The heating control of the pot 30 by the left and right heating coils 3 will be described with reference to the block diagrams of FIGS. Note that the control of the grill heating unit 6 and the control of the heating coil 3 at the center rear of the main body 1 are not directly related to the present invention, and thus the description thereof is omitted.

  The control means 118 includes outputs from the menu setting means 71 and the thermal power setting means 72 of the upper surface operation unit 7a, an inner temperature sensor 15a, outer temperature sensors 15b, 15c and 15d provided near the heating coil 3, an infrared sensor 17, and a reflection. The output of the rate measuring means 19 is input. Further, the control means 118 controls each temperature sensor 15a, 15b, 15c, 15d and the infrared sensor corresponding to the set temperature to heat the pan 30 by adjusting the temperature to the set temperature set by the upper surface operation unit 7a. The control temperature which controls the inverter means 100 based on the detected temperature of 17 is provided. Further, the reason for providing the plurality of temperature sensors 15a, 15b, 15c, 15d and the infrared sensor 17 is to prevent the temperature detection accuracy from being lowered due to deformation of the pan bottom when detecting the temperature of the pan 30.

  As shown in FIG. 6, the inverter unit 100 is configured such that an AC power source 117 is converted into a DC voltage by the rectifying unit 102 and connected to a switching unit configured by a series body of switching elements 103 and 105. Diodes 104 and 106 are connected in antiparallel to the switching elements 103 and 105, respectively, and a resonance circuit unit composed of the heating coil 3 and the resonance capacitor 107 is connected between the connection point of the switching elements 103 and 105 and the reference point of the DC voltage. To do. Snubber capacitors 108 and 109 are connected to the switching elements 103 and 105, respectively. By switching on and off the switching elements 103 and 105 exclusively at a high frequency, a high-frequency resonance current is supplied to the resonance circuit section constituted by the heating coil 3 and the resonance capacitor 107, and the load disposed in the vicinity of the heating coil 3 is heated.

  The control unit 110 inputs a target power level instruction to be applied to the load from the control unit 118, and controls the switching units 103 and 105 so that the output power of the inverter unit 100 becomes a target value. The input current conversion unit 112 converts the output signal of the detection unit 111 that detects the current input from the AC power source 117 into an appropriate level and outputs the converted signal to the control unit 110. The input voltage detection means 113 detects the voltage of the AC power supply 117, converts it to an appropriate level, and outputs it to the control unit 110. The inverter current detection unit 115 converts the output signal of the detection unit 114 that detects the current flowing through the resonance circuit unit into an appropriate level and outputs the converted signal to the control unit 110. The controller 110 inputs these signals, calculates inverter power that is input to the load, determines the state of the load, suitability for heating, etc., and exclusively controls the switching elements 103 and 105 to be turned on and off. A signal is output, and the level conversion unit 116 converts the switching elements 103 and 105 to an appropriate driving level to drive the switching elements 103 and 105. The control unit 110 outputs these states to the control unit 118.

  In the induction cooking device configured as described above, each step will be described with reference to the flowchart of FIG. 7 when the user cooks the fried food using the heating coil 3 on the right side of the main body 1.

  The first step S1 is a standby step waiting for the main power switch 9 of the main body 1 to be turned on. When the main power switch 9 is turned on, the process proceeds to the next step. Moreover, the pan 30 filled with oil before and after this step is placed in the center of the heating coil 3 on the right side of the main body 1.

  Step S <b> 2 is a menu setting step for setting a heating method for the pot 30. In this process, the heating power is input by the heating power setting means 72, or the automatic cooking menu is set by the menu setting means 71. Here, the menu setting means 71 of the upper surface operation unit 7a is operated while viewing the display unit 81a to select “fried food”.

  If “fried food” is set, the process proceeds to the next step S3. If “fried food” is not selected in the menu setting process S2, the process proceeds to step S4. If “fried food” is selected, the process proceeds to step S5. .

  Step S4 in which “fried food” is not set is not directly related to the present invention, and thus description thereof is omitted.

  Step S5 is a temperature setting step of setting the oil heating temperature by operating the arrow adjustment key 73. In this step, a set temperature, which is a temperature at which the pan 30 is heated to adjust the temperature, is set. Although the oil temperature suitable for cooking fried food varies depending on the food to be fried, it is often cooked at a temperature of about 150 to 200 ° C. Here, the set temperature is set to 180 ° C. suitable for making tempura such as shrimp, pumpkin, and salmon, and “180” is displayed on the display unit 81a (FIG. 5).

  The next step S6 is a cooking start step for waiting for the start of cooking. In this step, the input of the cut / start key 74 is waited, and when it is input, preheating for heating the oil temperature to the set temperature is started in order to start cooking the fried food. And it progresses to the next process.

  When preheating of fried food cooking is started, the next step S7 is a reflectance measurement step for measuring the reflectance of the pot 30 being used. In the reflectance measurement process, the reflectance of the pan 30 is measured from the output of the reflective photointerrupter 18 by the reflectance measuring means 19 and input to the control means 118, and used for correction when the pan is detected by the infrared sensor 17. The measurement may be performed only once at the beginning of cooking or periodically.

  The next step S8 is a temperature adjustment step for adjusting the temperature of the pan 30 to the set temperature. The temperature sensor that detects the temperature at the bottom of the pot 30 and uses it for temperature control in this step S8 is heated using the infrared sensor 17 that can detect the temperature of the pot 30 accurately and with high sensitivity. And in order to heat the temperature of oil to 180 degreeC, it is the process of heating the temperature of the pan 30 to 180 degreeC which is preset temperature, and adjusting temperature. However, when the mounting position of the pan 30 is bad or the bottom surface of the pan 30 is deformed, any one of the temperature sensors 15 (15a, 15b, 15c, 15d) detects a temperature higher than the detection temperature of the infrared sensor 17. When it does, the pot 30 is heated at the control temperature which will be 180 degreeC which is preset temperature using the temperature sensor which has detected the high temperature.

  However, at this time, if the detected temperature of the inner temperature sensor 15a is the highest, the deformation of the pan such as the case where the bottom center portion of the pan 30 is convex outward, and the placement position of the pan 30 are greatly increased. In this case, the heating of the pan 30 is stopped.

  Then, when the detected temperature reaches a value corresponding to the set temperature of 180 ° C. and a predetermined time has passed, the end of preheating is notified. The reason for waiting for a predetermined time after the temperature of the pan 30 reaches the set temperature until the notification of the end of the preheating is to eliminate the temperature unevenness of the oil.

  If the detected temperature of the infrared sensor 17 does not reach a certain temperature within a certain time in this process, the placement position of the pan 30 is inappropriate or the top plate 2 is prevented from being contaminated. It is determined that the pan 30 is heated by laying a sheet, and heating of the pan 30 is stopped. The condition at the time of determination in this case is to stop heating when the detected temperature does not reach 120 ° C. or more within 60 seconds from the start of heating.

  Step S9 is a correction step for the inner temperature sensor used during cooking. If the temperature detected by the inner temperature sensor 15a is kept at a constant temperature range while the pan 30 is temperature-controlled at step S8, the inner temperature sensor 15a It is determined that the detected temperature is stable. Then, the control means 118 controls the inverter means 100 by comparing the detected temperature of the inner temperature sensor 15a with the changed control temperature as the control temperature used when cooking the stably detected temperature. Of course, the set temperature “180” displayed on the display unit 81a is not changed, and the oil temperature is not changed.

  The inner temperature sensor 15 a detects the temperature of the pan bottom of the pan 30 through the top plate 2. For this reason, the detection condition of the detected temperature differs depending on the pan 30 due to the dent in the middle of the pan 30 or the like. While the pan 30 is kept at a constant temperature by the infrared sensor 17 that can accurately detect the temperature of the pan 30, the control temperature corresponding to the set temperature determined by the input of the operation unit in step S5 is set in step S9. By changing the correction to the detected temperature of the inner temperature sensor 15a that is stably detected at, the inner temperature sensor 15a can be used to accurately maintain the temperature of the pot 30 at the set temperature. I have to.

  Step S10 is a step of confirming whether the control temperature for controlling the inverter means 100 has been determined using the inner temperature sensor 15a. If it has not been determined yet, steps S8 and S9 are repeated.

  When the temperature detected by the inner temperature sensor 15a is continuously detected within a certain temperature range for a certain time, the process proceeds to the next step S11. For example, the fixed temperature range and the fixed time are ± 1 ° C. for the temperature detected by the inner temperature sensor 15a and the time is 60 seconds.

  Step S11 is a cooking step of frying tempura. In the cooking process, the temperature of the pan 30 is adjusted using the inner temperature sensor 15a. The pot 30 is temperature-controlled at the control temperature determined in step S9.

  However, the infrared sensor 17 and other temperature sensors (15b, 15c, 15d) always detect the temperature of the pan 30 as a backup of the inner temperature sensor 15a, and monitor whether the temperature of the pan 30 is normal.

  The next step S12 is a cooking end step. When the cut / start key 74 is pressed, the heating to the pan 30 is finished and the cooking is also finished.

  In the present embodiment, the correction of the inner temperature sensor 15a has been described. However, other temperature sensors 15b, 15c, and 15d can be corrected by the same method.

  Further, by correcting the temperature sensor 15, the temperature of the pan 30 can be accurately controlled by detecting the temperature of the pan 30 accurately without being affected by a slight dent generated while using the pan.

  According to the present embodiment described above, the temperature of the pan can be detected with high accuracy using the temperature sensor formed of the thermistor provided in close contact with the lower surface of the top plate.

2 Top plate 3 Heating coil 15 Temperature sensor 17 Infrared sensor 18a Infrared LED
18b Infrared phototransistor 19 Reflectivity measuring means 71 Menu setting means 118 Control means

Claims (1)

A top plate on which the pan is placed;
A heating coil provided below the top plate;
And infrared sensors that detect the temperature of the pan bottom and receives the infrared pan bottom of the pan is provided is emitted below the top plate,
A thermistor for detecting the temperature of pan bottom of the pan through the top plate is provided below the top plate,
Inverter means for supplying power to the heating coil;
An operation unit for setting a set temperature for heating the pan;
Control means for controlling the temperature by controlling the inverter means so that the temperature of the pan becomes the set temperature using the infrared sensor or the thermistor ,
The control means, when the cooking is also fried performs temperature control of the pot by the infrared sensor, a predetermined time only the detected temperature of the infrared sensor reaches the control temperature, further, the thermistor detection When the temperature stays in a constant temperature range for a certain period of time, it is determined that the temperature detected by the thermistor is stable, and the temperature detected stably is used when cooking. An induction heating cooker characterized in that the inverter means is controlled as a control temperature after that by comparing the detected temperature of the thermistor with the changed control temperature.