JP5492690B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that detects the temperature of a pan placed on a top plate with an infrared sensor.

  A cooking vessel (pan) is placed on the top plate provided on the top surface of the main body, and the pan is placed on the light receiving surface (light sensor window) of the infrared sensor that receives the infrared rays emitted from the cooking vessel and measures the temperature. Induction heating cooker equipped with an infrared sensor that emits infrared rays from the lower part of the top plate by a light emitting means and receives the emitted infrared rays reflected from the bottom of the pan placed on the top plate in order to detect whether or not Is described in Japanese Patent Application Laid-Open No. H11-228707.

  In addition, in order to detect the presence or absence of the pan placed on the top plate, infrared rays are emitted from the lower part of the top plate in the main body by a light emitting element, and reflected by the pan bottom of the pan placed on the top plate. What was described in patent document 2 is known as an induction heating cooking appliance provided with the light receiving element which receives the infrared rays which did.

JP 2008-27730 A JP 2005-149836 A

  However, in the above-described prior art induction heating cooker, even if the pan is placed on the top plate and accurately placed on the light receiving surface of the infrared sensor, it can be caused by the material, color, scratches, etc. of the pan bottom of the pan. A difference occurs in the reflectance for reflecting the infrared rays, and the amount of reflected infrared rays varies greatly.

  Therefore, there is a common problem in Patent Document 1 and Patent Document 2 that the presence or absence of a pan cannot be determined only by the amount of reflected infrared light.

The present invention has been made to solve the above-described problems, and is provided with a top plate on which a pan is placed, and a lower space provided between the inner heating coil and the outer heating coil . A heating coil; inverter means for supplying power to the heating coil; an infrared sensor provided below the top plate for receiving infrared radiation radiated from the pan bottom of the pan; and detecting the pan bottom temperature; and below the top plate A temperature sensor for detecting the temperature of the pan bottom of the pan, infrared light emitting means for emitting infrared rays toward the pan bottom of the pan, provided below the top plate, and the pan provided below the top plate Infrared light receiving means for receiving infrared light reflected from the bottom of the pot, infrared light emitted from the bottom of the pot and red light emitted toward the bottom of the pot by the infrared light emitting means An optical sensor window provided on the top plate through which the line and the emitted infrared light are reflected and transmitted by the pan bottom of the pan, and converted into a signal for determining the presence or absence of the pan based on the output of the infrared light receiving means Compared with the value in which the output value of the pan presence / absence detecting means is incorporated in advance, the reflectance measuring means for measuring the reflectance of the pan bottom based on the output of the infrared receiving means, the presence / absence detecting means of the pan, When it is impossible to detect the presence or absence of a pan, the inverter means is controlled to supply weak heating power to the heating coil, and when the temperature sensor shows a change indicating a temperature rise, the pan Control means for determining that the window is covered is provided , and the infrared sensor, the infrared light emitting means, and the infrared light receiving means are provided close to the lower portion of the gap of the heating coil .

  Further, the inverter means is configured to supply weak heating power to the heating coil when the presence / absence of the pan is undetectable as compared with the output value of the pan presence / absence detecting means. When the temperature sensor does not show a change indicating a temperature rise within a certain time, it is determined that the pan is out of the light sensor window, and control means for cutting off the supply of power to the heating coil It is equipped with.

  According to the induction heating cooker of the present invention, it is possible to accurately determine the presence or absence of a pan placed on 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. Explanatory drawing of a reflection type photo interrupter.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is an external perspective view of an induction heating cooker showing an embodiment of the present invention. 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.

  Upper surface operation portions 7a, 7b, 7c corresponding to the respective heating coils 3 are provided on the upper surface on the front surface side of the top plate 2, and the energization state of the heating coils 3 is set and operated. Corresponding to the upper surface operation parts 7a, 7b, 7c, upper surface display parts 8a, 8b, 8c are provided in the vicinity of the upper surface operation parts 7a, 7b, 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.

  Reference numeral 16 denotes an optical sensor window which transmits infrared rays emitted from the bottom of the pan 30. Originally, the top plate 2 is painted with a specific design so that the inside of the main body 1 cannot be seen. The optical sensor window 16 transmits the infrared rays radiated from the bottom of the pan 30 to the lower part of the top plate 2, and does not apply the coating partly, but the material of the top plate 2 (transparent) and the infrared ray-transmitting paint Has just been given. In this embodiment, since the left and right heating coils 3 are provided with the infrared sensors 17, the optical sensor windows 16 are also provided on the light receiving surfaces of the infrared sensors 17 described later (in FIG. 1, in the right side heating). The optical sensor window 16 provided in the coil 3 is covered with the pot 30 and hidden and cannot be seen).

  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 the cooking chamber so that it can be inserted and removed freely from the front opening, and cooked by placing ingredients such as fish and pizza on the grill net placed on the saucer. 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.

  The heating coils 3 arranged at the left and right and the central rear part are each composed of an annular inner heating coil 3a and an annular outer heating coil 3c arranged with an annular gap 3b on the outside thereof.

  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 the 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.

  Near the center of the heating coil 3 disposed on the left and right, an inner temperature sensor 15a among a plurality of temperature sensors 15 formed of a thermistor is provided in close contact with the lower surface of the top plate 2, and the heating coil 3, the temperature of the pan 30 placed above 3 is detected via the top plate 2.

  Similarly, in the gap 3b of the heating coil 3, outer temperature sensors 15b, 15c, and 15d (FIG. 2) formed of thermistors at equal distances from the center of the heating coil 3 and at equal intervals of 120 degrees are gap spacers. 14 is provided via a cushioning material (not shown), and is in close contact with the lower surface of the top plate 2 to detect the temperature of the pan 30 placed above the heating coil 3.

  The outer temperature sensors 15b, 15c, and 15d are configured to be provided in the gap 3b of the heating coil 3, but are not particularly limited thereto. For example, the structure provided in the outer periphery vicinity of the outer periphery of the outer side heating coil 3c or the structure used as the heating coil 3 without the clearance gap 3b which wound the inner side heating coil 3a and the outer side heating coil 3c without the gap may be sufficient.

  Further, the outer temperature sensors 15b, 15c, and 15d are not limited to three, and may be one or two, or three or more.

  Below the gap 3b in the vicinity of the gap 3b between the heating coils 3 disposed on the left and right, an infrared sensor 17 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. Is provided.

  The infrared sensor 17 is a sensor of a type using a thermal detection element, and the light receiving surface 17a of the optical sensor window 16 provided on the top plate 2 below the heating coil 3 at the position of the gap 3b of the heating coil 3. It is provided at the bottom.

  The light receiving surface 17a is provided with a lens, a light guide tube, and the like (not shown) for limiting the infrared viewing angle to be detected.

  In the gap 3 b between the heating coils 3 disposed on the left and right, a reflective photointerrupter 18 is provided at a position close to the infrared sensor 17 and away from the lower surface of the top plate 2.

  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 18 a and irradiates a thin beam of infrared light above the photosensor window 16 provided on the top plate 2. In addition, a visible light blocking plastic lens is formed on the light receiving surface of the infrared phototransistor 18b. The infrared light reflected by the object (the bottom of the pan) covering the photosensor window 16 is reflected by the previously irradiated infrared light. Receives light and outputs a current proportional to the amount of light received.

  The output of the infrared phototransistor 18b of the reflective photointerrupter 18 is input to the reflectance measuring means 19 and the pan presence / absence detecting means 20.

  In order to detect the temperature of the pan 30, the amount of infrared rays radiated from the bottom varies depending on the material, color, scratches, etc. of the pan even in the same temperature, so the pan 30 is determined from the amount of infrared detected by the infrared sensor 17. The temperature cannot be determined uniquely. Therefore, the accurate temperature of the pan 30 can be detected from the amount of infrared rays detected by knowing the emissivity.

  The emissivity is based on Kirchhoff's law (ε + ρ = 1) established between the emissivity ε of infrared energy (E = εσT4) radiated from the surface of the metal material and the reflectivity ρ of the surface (however, the transmittance) If the reflectance ρ of the pan 30 can be known, the emissivity ε of the pan 30 can be calculated.

The reflectance measuring means 19 is for detecting the emissivity of the pot 30, measures the reflectance of the bottom surface of the pot 30 placed on the top plate 2, and inputs it to the control means 118.

  The pan presence / absence detecting means 20 receives the infrared ray reflected by the infrared ray emitted from the infrared LED 18a in the reflection type photo interrupter 18 by hitting the bottom of the pan 30, and receives the infrared ray phototransistor 18b. A current generated as an output is converted into a voltage so that it can be detected by the control means 118 described later, and input to the control means 118.

  The upper surface operation unit 7a includes a thermal power setting unit 72 for setting thermal power and a menu setting unit 71 for selecting a cooking menu.

  The inverter means 100 generates a voltage of several hundred volts at a high frequency of several tens of kHz and supplies it to the heating coil 3.

  The control means 118 controls the inverter means 100 so that the pan 30 can be heated with the heating power set by the heating power setting means 72, or the menu selected from the automatic menu previously installed by the menu setting means 71. Based on this, the inverter means 100 is controlled, the emissivity is obtained from the signal of the reflectance measuring means 19 in order to accurately detect the temperature of the pot 30, the signal from the infrared sensor 17 is corrected, and the temperature of the pot 30 is determined. Based on the corrected signal, the power supplied from the inverter means 100 to the heating coil 3 is controlled based on the corrected signal, or the inverter means 100 supplies the heating coil 3 based on the signal from the temperature sensor 15. It controls power.

  In addition, the control means 118 is preinstalled with a voltage that has been confirmed in advance at the manufacturing stage as a voltage for comparison with the voltage of the pan presence / absence detection means 20.

  The case where a user cooks fried food using the heating coil 3 on the right side of the main body 1 in the induction heating cooker configured as described above will be described.

  First, the pan 30 filled with oil is placed in the center of the heating coil 3 on the right side of the main body 1 and the main power switch 9 is turned on to turn on the power. Operate to select "Fried" and then set the pan 30 temperature (oil temperature). The oil temperature suitable for cooking fried food is about 150 to 200 ° C., but here, the oil temperature is set to 200 ° C. Next, a fried food is started by operating a cut / start key (not shown).

  When fried food cooking is started, the infrared LED 18a in the reflective photointerrupter 18 is caused to emit light in order to detect whether the pan 30 covers the optical sensor window 16 so that the temperature of the pan 30 can be measured. The generated current is converted into a voltage by the pan presence / absence detection means 20, and the presence / absence of the pan is detected by comparing the converted voltage with the voltage previously confirmed by the control means 118.

  The voltage confirmed in advance is widely distributed depending on the difference in the material, color, scratches, etc. of the pan, and there are two voltage ranges: a voltage range in which it can be determined that the pan 30 is present and a voltage range in which the presence or absence of the pan 30 is not clearly determined. Divided into areas.

  When the control unit 118 determines that the value input from the pan presence / absence detection unit 20 has the pan 30, the control unit 118 has a heating power suitable for heating to the oil temperature of 200 ° C. with the set “fried food”. The inverter means 100 is controlled to supply power to the heating coil 3.

  Further, in the case where the value input from the pan presence / absence detection means 20 is a region where the presence / absence of the pan 30 is not clearly determined, the inverter means 100 is controlled so that the heating power becomes low, and the heating coil 3 is supplied with power, If the signal from the temperature sensor 15 is monitored and the signal changes indicating an increase in temperature, it can be determined that the pan 30 is heated by the heating coil 3 and the pan 30 is rising in temperature, and the infrared sensor 17 radiates from the pan 30. It is determined that the infrared rays being captured can be captured, and the inverter means 100 is controlled so that the heating power suitable for heating to the oil temperature of 200 ° C. with the set “fried food” is obtained, and electric power is supplied to the heating coil 3. Supply.

  If the signal from the temperature sensor 15 continues to be monitored for about 30 seconds and the signal does not change indicating an increase in temperature, it is determined that the pan 30 is placed out of the optical sensor window 16. To stop heating.

  According to the above-described embodiment, when the pan is placed out of the optical sensor window that transmits infrared rays radiated from the pan placed on the top plate, the heating can be surely stopped and the usability is improved. Can do.

2 Top plate 3 Heating coil 15 Temperature sensor 16 Optical sensor window 17 Infrared sensor 18a Infrared LED
18b Infrared phototransistor 19 Reflectance measuring means 20 Pan presence / absence detecting means 118 Control means

Claims (2)

A top plate on which the pan is placed;
A heating coil provided below the top plate and provided with a gap between the inner heating coil and the outer heating coil ;
Inverter means for supplying power to the heating coil;
An infrared sensor that is provided below the top plate and receives infrared radiation emitted from the pan bottom of the pan to detect the pan bottom temperature;
A temperature sensor that is provided below the top plate and detects the temperature of the pan bottom of the pan;
Infrared light emitting means that emits infrared light toward the pan bottom of the pan provided below the top plate;
Infrared light receiving means for receiving infrared light that is provided below the top plate and reflected from the bottom of the pan;
An infrared ray radiated from the bottom of the pan, an infrared ray emitted toward the pan bottom by the infrared light emitting means, and an optical sensor window provided on the top plate that reflects and transmits the emitted infrared ray at the pan bottom of the pan;
A pan presence / absence detecting means for converting the signal into a signal for determining the presence / absence of the pan based on the output of the infrared light receiving means;
Reflectance measuring means for measuring the reflectance of the pan bottom based on the output of the infrared light receiving means;
When the presence / absence of the pan is not detectable, the inverter means is controlled so as to supply weak heating power to the heating coil when the output value of the pan presence / absence detection means is not detected. And when the temperature sensor shows a change indicating a temperature rise, comprising a control means for determining that the pan covers the light sensor window ,
An induction heating cooker, wherein the infrared sensor, the infrared light emitting means, and the infrared light receiving means are provided close to the lower portion of the gap of the heating coil .   When the presence / absence of the pan is not detectable, the inverter means is controlled so as to supply weak heating power to the heating coil when the output value of the pan presence / absence detection means is not detected. When the temperature sensor does not show a change indicating a temperature rise within a predetermined time, it is determined that the pan is out of the optical sensor window, and control means for cutting off the power supply to the heating coil is provided. The induction heating cooker according to claim 1, wherein

Images