JP2013062188A - Induction heating cooker - Google Patents

Abstract

An induction heating cooker capable of controlling boiling soup with high viscosity without spilling.
An induction heating cooker according to an embodiment detects more radiation energy of glass by comparing the spectral radiation detection characteristics of an infrared sensor with the radiation energy of a pan having a pan bottom with an emissivity of approximately 100% in the infrared region. When the boiling is detected, the thermal power is reduced, and the arrival of the boiling is judged by the change in the detected value of the infrared sensor after the thermal power is reduced. Then, the heating control is repeated, the boiling of the soup with high viscosity is accurately detected, and the boiling is controlled.
[Selection] Figure 34

Description

  The embodiment relates to an induction heating cooker.

  Some conventional induction heating cookers include an infrared sensor that detects infrared rays radiated from an object to be heated below the top plate and a temperature sensor that detects the temperature of the top plate. There is also a technique for calculating the temperature of the heating container by using an infrared sensor signal and a temperature sensor when the temperature of the top plate is low.

  However, according to the conventional heating control technology, when cooking soup with relatively high viscosity such as miso soup and soup while monitoring the temperature of the bottom of the container with an infrared sensor, the cooking temperature is boiled to a low temperature of 100 ° C. However, there was a problem that it was difficult to control the cooking without spilling by continuing heating for a while.

JP 2005-38739 A JP 2005-216687 A Japanese Patent No. 4321278

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an induction heating cooker capable of accurately detecting boiling of soup with relatively high viscosity and controlling the boiling without spilling. .

  An induction heating cooker according to an embodiment includes a top plate on which an object to be heated is placed, a heating unit that is installed below the top plate and induction-heats the object to be heated by a heating coil, the top plate, An infrared sensor that detects infrared radiation radiated from the object to be heated, and a control unit that controls the heating power of the heating unit according to a temperature rise control data sequence determined by a detection value of the infrared sensor, The spectral radiation detection characteristic of the infrared sensor is compared with the radiation energy of a pan having a pan bottom with an emissivity of about 100% in the infrared region, and the radiation energy of the glass is detected more. Detect and boil, and at the time when boiling is detected, the thermal power is reduced, and the detection value change of the infrared sensor after the thermal power is reduced And determining a continuation or stop of the boiling detecting.

The flowchart which shows the induction heating control which a thermal power control apparatus performs in the induction heating cooking appliance of 1st Embodiment. The figure which shows an example of the data series which the thermal-power control apparatus of the induction heating cooking appliance of 1st Embodiment uses for heating control. The external appearance perspective view of the state which incorporated the induction heating cooking appliance of 1st Embodiment in the kitchen cabinet. The top view which shows the induction heating cooking appliance of 1st Embodiment in the state which removed the top plate. The top view which shows the display state of the display part of the induction heating cooking appliance of 1st Embodiment. The vertical side view of the induction heating cooking appliance of 1st Embodiment. The functional block diagram which shows the structure of the control system of the induction heating cooking appliance of 1st Embodiment. The flowchart which shows the induction heating control which a thermal power control apparatus performs in the induction heating cooking appliance of 2nd Embodiment. The figure which shows an example of the data series which the thermal-power control apparatus of the induction heating cooking appliance of 2nd Embodiment uses for heating control. The graph which shows the variation of the data series (10) which the said thermal-power control apparatus uses for heating control. The figure which shows the example of handling of the detection output obtained from two temperature sensors by a list in the induction heating cooking appliance of 2nd Embodiment. It is a graph explaining a prior art, The figure (a) is a graph of the temperature distribution of the lower surface and upper surface of the top plate of a heating cooker, The figure (b), (c) is the lower surface, upper surface, frying pan of a top plate. The graph which shows the infrared radiation energy from a lower surface. The figure which shows the spectral characteristic of the top plate in the conventional induction heating cooking appliance. In the conventional induction heating cooker, it is a graph of the temperature change at the time of heating the thing with a thick pan-bottom plate thickness of a frying pan, The figure (a) is a graph of a thermal power (electric power) change, (b). Is the temperature change of the bottom of the pan and the top plate, (c) is a graph showing the change of the detection output of the infrared sensor. Explanatory drawing which shows the temperature distribution and electric current distribution in the case of carrying out induction heating of the frying pan in the induction heating cooking appliance of 1st Embodiment. The graph which shows the relationship between the top plate lower surface temperature Tpu and the detection value V of an infrared sensor at the time of making a frying pan empty in the induction heating cooking appliance of 1st Embodiment. The flowchart of the suitable temperature detection process which a thermal-power control apparatus performs in the induction heating cooking appliance of 1st Embodiment. Explanatory drawing of the thermal power set value data series which changes before and after optimal temperature detection in the optimal temperature detection process which the thermal power control apparatus of the induction heating cooking appliance of 1st Embodiment performs. The flowchart of the infrared target temperature change process which a thermal power control apparatus performs in the induction heating cooking appliance of 1st Embodiment. The graph which shows the infrared temperature upper limit value set variably according to the heating elapsed time at the time of temperature rising heating in the induction heating cooking appliance of 1st Embodiment. The induction heating cooker of 1st Embodiment WHEREIN: The graph which shows the relationship between the temperature rise value per 1kW * s of an iron pan and various stainless steel pans, and oil temperature. FIG. 22 (a) is a graph showing the transition of the actual water temperature and the detection temperature of the infrared sensor when 0.5 L of water is put into each of an enamel pan and a stainless steel pan and heated at 1.5 kW thermal power, and FIG. The graph of the transition of the time change rate of the infrared detection value. FIG. 23 (a) is a graph showing the transition of the actual water temperature and the detection temperature of the infrared sensor when 1.5L of water is placed in each of an enamel pan and a stainless steel pan and heated at 1.5 kW thermal power, and FIG. The graph of the transition of the time change rate of the infrared detection value. The flowchart of the water heater control example 1 by the induction heating cooking appliance of 1st Embodiment. The flowchart of the kettle control example 2 by the induction heating cooking appliance of 1st Embodiment. FIG. 26 (a) is a graph showing the transition of the actual water temperature and the detection temperature of the infrared sensor when 0.5L of water is put into each of an enamel pan and a stainless steel pan and heated at 1.5 kW thermal power, and FIG. FIG. 26C is a graph of the change in the time change rate of the infrared detection value. FIG. 26C is a graph of the change in the time change rate of the infrared detection value. FIG. 27 (a) is a graph showing the transition of the actual water temperature and the detection temperature of the infrared sensor when 1.5L of water is placed in each of an enamel pan and a stainless steel pan and heated at 1.5 kW thermal power, and FIG. FIG. 27C is a graph of the change in the time change rate of the infrared detection value, and FIG. 27C is a graph of the change in the time change rate of the infrared detection value. The flowchart of the water heater control example 3 by the induction heating cooking appliance of 1st Embodiment. FIG. 29 (a) is a graph showing the transition between the actual water temperature and the detection temperature of the infrared sensor when water is poured into the enameled pot that has been heated after the first boiling and the second boiling is performed, and FIG. FIG. 29C is a graph of the change in the time change rate of the infrared detection value, and FIG. 29C is a graph of the change in the time change rate of the infrared detection value. FIG. 30 (a) is a graph showing the transition between the actual water temperature and the detected temperature of the infrared sensor when water heated by other heating means is additionally heated by the heating means of this embodiment and boiled, FIG. 30 (b) ) Is a graph of the change in the time change rate of the infrared detection value, and FIG. 30C is a graph of the change in the time change rate of the infrared detection value. The flowchart of the water heater control example 4 by the induction heating cooking appliance of 1st Embodiment. The flowchart of the kettle control example 5 by the induction heating cooking appliance of 1st Embodiment. FIG. 33 (a) is a graph showing the transition of the actual water temperature, the detection temperature of the infrared sensor and the bottom temperature of the water when water is poured into the enamel pan and heated at 1.5 kW of thermal power. The graph of change of the time change rate change of a detected value. The flowchart of the water heater control example 6 by the induction heating cooking appliance of 1st Embodiment. The flowchart of the water heater control example 7 by the induction heating cooking appliance of 1st Embodiment.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

(First embodiment)
Hereinafter, a first embodiment applied to an induction heating cooker incorporated in a system kitchen will be described with reference to FIGS. FIG. 3 is an external perspective view of the kitchen cabinet 1 with the heating cooker 2 incorporated therein, and FIG. 4 is a plan view of the cooker body 3 shown with the top plate removed. A cooker body 3 of the heating cooker 2 is incorporated in a state of being dropped into an opening 4 provided in the cabinet 1. A roaster portion 5 shown in FIG. 3 is provided at the lower portion of the cooker body 3.

  As shown in FIG. 4, the cooker body 3 has an open top surface, two induction heating coils 8 and 9 serving as heating means are provided on the front side inside, and another heating means at the center back. For example, a heater 10 made of a radiant heater is provided. In addition, a display circuit board 11 is disposed in the cooker body 3, and display groups 12A and 12B made up of a number of light emitting diodes for displaying heating intensity are mounted on the display circuit board 11. In addition, indicators 15A and 15B made of, for example, fluorescent display tubes are mounted.

  Further, as shown in FIGS. 3 and 5, a transparent glass top plate 16 made of heat-resistant glass is disposed on the upper surface of the cooker body 3 so as to cover the induction heating coils 8 and 9 and the heater 10 from above. The In the top plate 16, the left and right induction heating coils 8, 9 and the portions corresponding to the upper portions of the heater 10 are provided with cooker placement display portions 17, 18, 19 having a circular pattern, respectively.

  FIG. 5 shows a state in which light is emitted from the display unit described below, and light is displayed as if each display unit on the top plate 16 is raised. On the back surface of the top plate 16, on the front side of the cooking device placement display portions 17 and 18, a punching hole in which cooking condition display portions 12AH and 12BH are formed in the coating film and located above the display device groups 12A and 12B. The cooking condition display parts 15AH and 15BH are similarly provided by the punched holes located above the indicators 15A and 15B. In addition, each of these cooking condition display parts 12AH, 12BH, 15AH, and 15BH is illuminated and displayed from below by a corresponding display, respectively, and as shown in FIG. Visible.

  In addition, input guide display portions 20AH to 27AH and 20BH to 27BH are similarly provided in the lower surface of the front edge portion of the top plate 16 (the portion protruding forward from the cooker body 3). These input guidance display sections 20AH to 27AH and 20BH to 27BH are optically displayed so as to emerge due to light emission from a light emitter (not shown) arranged inside the main body 3. When the light emitter is turned off, the inside of the top plate 16 is almost invisible (so-called blackout state).

  The right input guidance display sections 20AH to 27AH and the left input guidance display sections 20BH to 27BH have basically the same configuration, and the right input guidance display sections 20AH to 27AH, The configuration of the operation unit provided below the left input guidance display units 20BH to 27BH is basically the same, so the operation unit below the right input guidance display units 20AH to 27AH and the like. This will be described below.

  The input guidance display unit 20AH is for starting / cutting cooking, the input guidance display unit 21AH is for menu selection, the input guidance display unit 22AH is for setting up heating intensity and heating time, and the input guidance display unit 23AH is The down setting and input guidance display sections 24AH to 27AH are for heating intensity setting. Further, below these input guidance display units 20AH to 27AH, operation units 20AT to 27AT for detecting that the user performs a touch operation with a finger based on a change in capacitance are provided (see FIG. 7).

  FIG. 6 is a vertical side view of the heating cooker 2. A shield case 31 is arranged inside the cooling duct 30. When the shield case 31 extends downward from the central portion of the induction heating coil 8, the shield case 31 is a substantially L-shaped container bent in the horizontal direction (leftward in FIG. 6) at a position directly below the air outlet 30a. . In the back of the shield case 31, an infrared sensor 32 is arranged with the light receiving portion (infrared filter 32a) facing in the horizontal direction (rightward in FIG. 6). The infrared sensor 32 is composed of a unit that integrally includes the infrared filter 32a, the infrared detector 32b, and a signal processing circuit (not shown). Further, a condensing / reflecting portion 33 is disposed in a portion corresponding to the position directly below the air outlet 30 a inside the shield case 31. The condensing / reflecting portion 33 constitutes a unit integrated with the infrared sensor 32 and is disposed inside the shield case 31.

  An opening 34 is formed in a portion of the shield case 31 located above the light collecting / reflecting portion 33, and infrared rays emitted from a cooking utensil 35 such as a frying pan are collected through the opening 34. It is directed toward the reflection part 33.

  On the lower surface of the top plate 16, for example, a thin film 36 formed by sputtering a metal material such as silicon or a metal nitride material such as silicon nitride by a sputtering method is provided so that infrared rays and visible light are semi-transmitted. It is configured. The thin film 36 is not formed on the lower surface of the top plate 16 where the opening 34 is in close contact, that is, on the field of view of the infrared sensor 32, and a transparent infrared transmission window 37 is formed. . Thereby, the infrared rays radiated from the cooking utensil 35 are efficiently transmitted through the infrared transmission window 37.

  In such a configuration, the condensing / reflecting unit 33 reflects the infrared radiation radiated from the cooking utensil 35 via the top plate 16 (infrared transmitting window 37) in a substantially horizontal direction and condenses the infrared sensor 32 (see FIG. 6 (see the optical path indicated by a broken line).

  By the way, when the transparent infrared transmission window 37 is provided in this way, the inside of the induction heating cooker 2 can be seen through the infrared transmission window 37. Therefore, an infrared transmission filter 38 is provided in a portion facing the infrared transmission window 37 inside the opening 34. The infrared transmission filter 38 has a wavelength transmission region in a wider range than the infrared filter 32a (a wavelength region in a range wider than the band W in FIG. 13), and is configured by a member having a characteristic that does not transmit visible light. . That is, the infrared filter is doubled in the middle of the infrared light path from the cooking utensil 35 to the infrared sensor 32 via the light collecting / reflecting portion 33. The infrared transmission filter 38 may be configured to have a wavelength transmission region including both the band V and the band W.

  Further, on the lower surface of the top plate 16, a temperature sensor 39 a composed of, for example, a thermistor is provided at the inner peripheral side of the induction heating coil 8 and the portion located above the portion around which the induction heating coil 8 is wound. , 39b are arranged. These temperature sensors 39 a and 39 b detect the temperature of the lower surface of the top plate 16.

  FIG. 7 is a functional block diagram showing the configuration of the control system. The thermal power control device (control unit) 41 is provided inside the cooker body 3 and is constituted by a microcomputer. The thermal power control device 41 receives operation signals from operation units (operation means) 20T to 27T disposed below the top plate 16, and receives temperature detection signals from the infrared sensor 32 and the temperature sensor 39 from each sensor. Are input via the detection units 32c and 39c corresponding to the above.

  The thermal power control device 41 controls the operation of the display units 12H, 15H, 20H to 27H and controls the inverter (high-frequency current supply means) 42 based on these inputs and a pre-stored control program. A high frequency current is supplied to the heating coil 8 (and 9) via the inverter 42 and controlled. For example, when the user operates the operation units 20T to 27T to select the cooking menu and set the cooking conditions, the display of the corresponding display units 12H, 15H, and 20H to 27H is controlled and the corresponding heating control is performed. .

  A resonance capacitor 43 is connected to the induction heating coil 8 in series. Since the coil 8 or the capacitor 43 performs output adjustment according to the material of the cooking utensil 35, the number of turns of the coil 8 is variable (for example, a multistage coil configuration), or the capacity of the capacitor 43 is variable. You may comprise as follows. The inverter 42 is supplied with a commercial AC power supply 44 converted to DC via a rectifier circuit 45 as a driving power supply. Further, the commercial AC power supply 44 is also supplied to the heater 10 (not shown in FIG. 7) via an energization control unit (not shown).

  Further, current transformers 46 and 47 are arranged on the input side of the rectifier circuit 45 and the output side of the inverter 42, respectively, and their detection signals are given to the thermal power control device 41. And the thermal-power control apparatus 41 detects the input current ip to the heating cooker 2, and the output current (coil current) ic of the inverter 42. FIG. In the above, the induction heating coils 8 and 9, the inverter 42, and the resonant capacitor 43 constitute a heating means 48.

  Next, the temperature measurement principle of the induction cooking device of the embodiment will be described. Vpu, Vpt, and Vb shown in FIG. 12 indicate infrared radiation energies from the upper surface, the vicinity of the lower surface, and the lower surface of the frying pan, respectively, and the energy Vto input to the infrared sensor 32 is (= Vpu + Vpt + Vb). In FIG. 12, since energy Vpt and Vb are transmitted through the top plate 16 and enter the infrared sensor 32, the energy Vpt and Vb are smaller than the infrared radiation energy Vpu from the bottom surface of the top fret. Note that Vpt> Vb is because the emissivity of a frying pan made of stainless steel (SUS) is small.

  FIG. 14A shows power changes P1 and P2 when heating a pan with a thick pan bottom (large heat capacity) and a pan with a small pan bottom (small heat capacity). FIG. 14B also shows temperature changes at the bottom of the pan (Tb1, Tb2) and the bottom surface of the top plate (Tpu1, Tpu2) when the thick and thin pan bottoms are similarly heated. . And FIG.14 (c) shows the change of the detection output of an infrared sensor as Vto1 and Vto2 about the same heating case.

  When the temperature at the bottom of the pan rises rapidly, such as when preheating during frying pan cooking, as shown in FIG. 12A, the temperature at the top surface of the top plate rises rapidly, but the temperature at the bottom surface does not rise. As described above, this is due to the fact that the top plate is made of glass, has low thermal conductivity, and has a large heat capacity. On the other hand, the frying pan has a low emissivity, so even if the temperature rises, less infrared is radiated, but the top plate is close to the bottom of the pan, so the temperature rises due to heat conduction, and the infrared rays radiated from the upper surface are also emitted. Increases rapidly. Therefore, when the infrared radiation energy through the top plate is not taken into consideration, the temperature detection accuracy is deteriorated.

  More specifically, FIGS. 12B and 12C correspond to cases (2) and (5) in FIG. 12A, respectively, and the pan bottom temperature Tb of the frying pan at times t1 and t5 in FIG. The upper surface temperature Tpt and the lower surface temperature Tpu of the top plate, and detection values Vb, Vpt, Vpu of the infrared sensor corresponding to these temperatures are shown. The pan bottom temperature Tb is 250 ° C. for all. In the case of FIG. 12B where the temperature of the top plate is low, the total detection value Vto of the infrared sensor should be (20 mV + 4 mV + 10 mV =) 34 mV. This corresponds to a detection temperature of 250 ° C.

  On the other hand, in the case of FIG. 12C where the temperature of the top plate is high, the total detection value Vto of the infrared sensor should be (20 mV + 50 mV + 300 mV =) 370 mV. This corresponds to a detection temperature of 310 ° C. Therefore, an error of 60 ° C. is generated.

  Further, the total detection value Vto of the infrared sensor has a very large proportion of Vpu corresponding to the radiation energy from the lower surface of the top plate. If the value corresponding to Vpu is estimated from the temperature detected by the thermistor, the estimation itself becomes inaccurate. That is, in induction heating, as shown in FIG. 15, since the distribution state of the induction current in the pan bottom varies, the variation in temperature distribution also increases. Then, the variation in the temperature distribution of the top plate also increases, so that the detection result of the infrared sensor and the temperature of the bottom surface of the top plate detected by the thermistor are different. Further, since the cooling air circulates on the lower surface side of the top plate, a difference also occurs between the temperature on the lower surface of the top plate and the temperature detected by the thermistor.

  And detection value Vpt changes with top plate upper surface temperature Tpt, and detection value Vb changes with the emissivity of a pan. Therefore, if the pan bottom temperature is detected based on a large error (Vto−Vpu) in both cases, the detection error becomes very large. A specific example will be described below.

  FIG. 16 shows the relationship between the top plate lower surface temperature Tpu and the detection value V of the infrared sensor when the frying pan is in an empty state. The detection value Vpu rises exponentially based on the lower surface temperature Tpu. The detection value Vgo (= Vpu + Vpt) has a characteristic in which the detection value Vpt increases as the temperature Tpt increases, and is added to the detection value Vpu. Further, the total detection value Vto is high even when the pan bottom temperature Tb is low at the initial stage of heating and the temperature of the top plate is low. Therefore, a characteristic in which a substantially constant detection value Vb based on the temperature Tb is added to the detection value Vgo. It becomes.

  When heating is started, the pan bottom temperature Tb, the top plate upper surface temperature Tpt, and the lower surface temperature Tpu increase in this order, so that the ratio of Vb to the total detection value Vto becomes large at the beginning of heating, but the time passes and the top As the temperature of the plate rises, the proportion occupied by Vgo increases. In the case of FIG. 12C, the total detection value Vto is 370 mV, and in the conventional method, Vpu = 300 mV output corresponding to Tpu = 220 ° C. is subtracted to become Vo5 = 70 mV. In this case, if Tpu = 210 ° C. and the temperature is detected 10 ° C. lower, Vpu = 260 mV and Vo5 = 110 mV. This value corresponds to a detection temperature of 300 ° C. That is, in the conventional method, if there is a detection error of 10 ° C. on the temperature of the bottom surface of the top plate, the detection error of the pan bottom temperature is 50 ° C.

  In addition, when the pan bottom of the frying pan is painted, the radiant heat from the pan bottom increases, so Vb is about three times as high as 60 mV compared to the case of glossy SUS. Then, in the case of FIG. 12C, the total detection value Vto is 410 mV, and when Vpu = 300 mV is reduced by the conventional method, Vo5 = 110 mV. That is, since it corresponds to the detected temperature of 300 ° C., the detection error of the pan bottom temperature is also 50 ° C.

  On the other hand, in the induction heating cooker of the embodiment, during the period when the temperature starts to rise, the temperature rise control data series is selected and set according to the detection output of the temperature sensor close to the temperature of the object to be heated. By determining the set value according to the temperature rise control data series set according to the detection output of the infrared sensor corresponding to the radiant energy from the bottom surface of the top plate, the degree of temperature rise can be adjusted even when the heat capacity of the object to be heated is small. Control with high accuracy and reliably prevent the object to be heated from reaching an excessively high temperature state.

  Next, the operation of the embodiment will be described with reference to FIGS. FIG. 2 shows an example of a temperature rise control data series (except for the data series (10 ')) that the thermal power control apparatus 41 stores and holds as a data table in an internal memory. 2 represents the output voltage Vto of the infrared sensor 32 used for the data series (1) to (9) together with the scale (upper axis) of the lower surface temperature Tpu of the top plate 16 used for the data series (10 ′). The scale (lower axis) of [mV] is shown, and the vertical axis is the heating power P [kW] of induction heating. Data series (1) to (9) show a series of temperature rise control data using the lower surface temperature Tpu, which rises in increments of 25 ° C. from 25 ° C., as a parameter.

  In this case, the thermal power decay rate (straight line) of the data series (1) to (9) depends on the infrared energy radiated when the temperature of the bottom of the shiny SUS pan reaches 250 ° C., for example. Thus, the voltage Vb is set to correspond to 20 mV output from the infrared sensor 32. The data series (1) to (9) discretely indicate rough values for the lower surface temperature Tpu, but the data actually used is obtained by dividing the lower surface temperature Tpu in more detail.

  For example, in the data series (1), when the lower surface temperature Tpu = 25 ° C., when the output voltage Vto = 10 mV is reached, the thermal power P is reduced from the initial value 3 kW, and when the output voltage Vto = 30 mV is reached, the thermal power P is the lowest output. This is set to 200W. Further, in the data series (6), when the lower surface temperature Tpu = 150 ° C., the thermal power P is reduced from the initial value 3 kW when the output voltage Vto = 140 mV, and when the output voltage Vto reaches 160 mV, the thermal power P is minimum output. Set to 200W. When the lower surface temperature Tpu changes, the data series to be used is dynamically changed accordingly.

  Of these data series, the data series (9) is set as the upper limit. That is, when the output voltage Vto becomes larger than the data series (9), the thermal power P decreases according to the slope of the data series (9), and when the output voltage Vto becomes 360 mV, the thermal power P (output) becomes 0 kW. Therefore, since the pan bottom temperature does not rise any further, the data series (9) becomes the upper limit.

  In addition, as a setting method of this upper limit value, for example, a data series (not shown) located on the right side of the data series (9) is further set, and the bottom surface temperature Tpu is 250 at the bottom temperature of the SUS pan described above. If a data series in which the slope is vertical at a temperature corresponding to the case of ° C. is set, the data series becomes the upper limit. This upper limit can be arbitrarily set. For example, if the slope of the data series (6) corresponding to the lower surface temperature Tpu = 150 ° C. is set to be vertical, the data series (6) becomes the upper limit.

  Moreover, about these data series (1)-(9), when following a normal cooking procedure, it is used in the period which raises the temperature of cooking utensils 35, such as a frying pan. The “period of increasing the temperature” means a period until the detection value of the infrared sensor 32 reaches the upper limit value of the temperature increase data series (data series (9)). For example, the data series (1) to ( For 9), increase the temperature by preheating the cooking utensil 35 such as a frying pan, heating until the oil in the fried food cooking reaches an appropriate temperature, or recovering the temperature of the oil that was reduced when the food was added in the fried food cooking. This is a period in which the heating power is raised when it is necessary to make the temperature of the cooking appliance 35 reach the target temperature quickly in a short time. The data series (1) to (9) are data series for proportionally controlling the thermal power P according to the detection output of the infrared sensor 32.

  The data series (10 ′) [temperature control data] is thermal power data used when cooking is performed according to the temperature Tpu detected by the temperature sensor 39, and the thermal power P is proportionally controlled according to the detection output. It is a data series for doing this. This data series (10 ′) is data for controlling the upper limit value of the thermal power in order to prevent the temperature of the cooking utensil 35 from rising excessively. By positioning it on the right side of the data series (9), for example, When the transparent infrared transmission window 37 is dirty, the function of preventing excessive temperature rise (over temperature rise prevention function) is performed when infrared rays cannot be detected well. That is, by setting the heating power upper limit value of the data series (10 ') higher than the heating power upper limit value of the data series (9), safe cooking is possible.

  FIG. 1 is a flowchart showing induction heating control performed by the thermal power control device 41. First, the lower surface temperature Tpu of the top plate 16 is detected based on the output voltage of the temperature sensor 39 (step S1), and then the output voltage Vto (lower horizontal axis in FIG. 2) of the infrared sensor 32 is detected (step S2). ). Then, the temperature rise heating power set value PS1 is set based on the data series shown in FIG. 2 according to the temperature Tpu and the output voltage Vto (step S3). That is, one of the data series (1) to (9) is selected according to the temperature Tpu, and the heating thermal power PS1 is set according to the output voltage Vto on the selected data series.

  For example, when the temperature Tpu is detected as 100 ° C., the data series (4) in FIG. 2 is selected. When the output voltage Vto of the infrared sensor 32 changes from 80 mV to 85 mV, the thermal power setting value PS1 based on the data series (4) is changed from 1.5 kW to 0.8 kW according to the change. That is, as shown in step S6, when the current thermal power P is different from the thermal power PS1 set as the target value in step S3, control is performed so that the current thermal power P matches PS1.

  In the above-described example, it is assumed that the temperature Tpu does not change even if the output voltage Vto of the infrared sensor 32 changes. However, actually, if the output voltage Vto increases, the temperature Tpu also increases. Therefore, the actual thermal power PS1 is slightly shifted to the lower right from the data corresponding to the thermal power of 1.5 kW in the data series (4), and is 1.5 kW to 0.8 kW located on the extension line of the output voltage Vto (85 mV). Will be set in between.

  That is, in normal cooking in which the cooking utensil 35 is gradually heated, when the temperature of the cooking utensil 35 rises in the initial stage, the temperature Tpu and the output voltage Vto of the infrared sensor 32 rise. Referring to FIG. 2, the thermal power set value PS1 moves slowly from a position where the thermal power of the data series having a low temperature Tpu is large toward a position where the thermal power is small, that is, diagonally downward to the right. When the temperature Tpu reaches 220 ° C., the thermal power set value PS1 decreases along the data series (9) set as the upper limit value so that the temperature of the cooking utensil 35 does not increase any further.

  On the other hand, when the cooked product is put into the cooking utensil 35 while the cooking utensil 35 is being heated, the temperature of the cooking utensil 35 is rapidly reduced. At this time, the lower surface temperature Tpu of the top plate 16 does not change so much, but the output voltage Vto of the infrared sensor 32 decreases at a stretch. Therefore, the thermal power set value is controlled to increase at a stretch along the data series based on the temperature Tpu. . This control will be described later.

  Subsequently, it is determined whether or not the temperature Tpu (upper horizontal axis in FIG. 2) is 220 ° C. or higher corresponding to the data series (9) (step S4). Is controlled in accordance with a data series (10 ′) that functions as an excessive temperature rise prevention function. This corresponds to proportional control with a function of g (Tpu) shown in step S5 by lowering the thermal power set value based on the data series (10 ') when the temperature Tpu increases.

  In this operation, the lower surface temperature Tpu of the top plate 16 rises higher than the upper limit value for preventing excessive temperature rise in the data series (9) based on the detection output of the infrared sensor 32, so that the infrared detection is appropriately performed. Corresponds to the case that does not work. In this case, the thermal power is controlled by a data series (10 ') having only the temperature Tpu as a parameter.

  In the induction heating cooker according to the present embodiment, the following heating control is also performed at the time of temperature rising heating. Control is performed to correct the upper limit temperature of the infrared sensor 32 in accordance with the temperature detected by the thermistor temperature sensor 39. That is, in the graph of FIG. 20, at the start of heating, the set value of the upper limit temperature data is set to a broken line AD1 (in FIG. 20, 300 as the infrared AD value). As the temperature of the top plate 16 and the cooker (pot) rises, the accuracy of the temperature detected by the temperature sensor 39 increases, and the upper limit temperature set value of the infrared temperature sensor 32 is changed to a high-temperature broken line AD2 (infrared AD value). 490), and sequentially shifted to a broken line AD3 (same as 620). Finally, the normal heating target value AD4 (650) is set. For example, control is performed at the upper limit temperature AD1 until the top plate temperature Tpu by the temperature sensor 39 reaches 200 ° C. Then, control is performed at the upper limit temperature AD2 until the top plate temperature Tpu reaches 250 ° C., and control is performed at the upper limit temperature AD3 until Tpu reaches 280 ° C., and this Tpu exceeds 280 ° C. And the normal heating target upper limit value AD4. By controlling the temperature raising and heating in this way, it is possible to reliably prevent over-temperature heating.

  In general, even if the detection output for the target temperature by the infrared sensor 32 is the same depending on the material of the pan, the detection temperature by the temperature sensor 39 may vary greatly. When the same amount of integrated power is applied, the actual temperature rise of the pot is almost the same even if the pot is made of different materials. However, the temperature detection value by the temperature sensor 39 tends to be lower than the temperature measurement value by the infrared sensor 32. Therefore, when the same integrated power amount is applied, the infrared temperature detection value is corrected so that the temperature rise by the temperature sensor 39 substantially matches the infrared temperature detection value.

  For this purpose, the following processing is performed. In the initial stage of heating, measure the accumulated electric energy required to raise the pan temperature by a certain temperature range, determine the pan material according to the accumulated electric energy, and use it for heating temperature control The control data table is changed, and the temperature detected by the temperature sensor 39 when the target temperature is reached is matched with the temperature measured value by the infrared sensor 32. This temperature rising heating control will be described with reference to the flowchart of FIG. First, it is determined whether or not the infrared target temperature has already been corrected during the current heating / heating control (step S111). If corrected, the temperature raising heating is continued with respect to the corrected infrared target temperature.

  If the infrared target temperature has not been corrected, then the infrared target temperature (upper limit value) for the standard pan is selected (step S112). Then, it is determined whether or not the temperature detected by the temperature sensor 39 has increased by 30 ° C. from the heating start temperature. If the heating start temperature has increased by 30 ° C., power integration is started, and it is determined whether or not the power integration start temperature Tst has further increased by 40 ° C. (Tde = Tst + 40 ° C.) (step S113). If the temperature has not risen by 40 ° C, heating is continued.

  If it is determined that the temperature detected by the temperature sensor 39 has increased by 40 ° C. from the power integration start temperature Tst, then the integrated power amount (W · sec) until the temperature rises by 40 ° C. from the Tst temperature is calculated (step S114). Subsequently, in order to correct the infrared target temperature in accordance with the material of the pan, the target temperature is obtained by the following arithmetic expression, and this is reset to the infrared target temperature (step S115).

Target temperature = (corresponding integrated power amount of standard pan / integrated power amount of the pan)
× Infrared target temperature of the standard pan In other words, immediately after the heating of the cooking utensil 35 where the temperature detected by the thermistor temperature sensor 39 tends to be lower than the actual temperature of the cooking utensil 35, the upper limit temperature setting value of the infrared target temperature is lowered. By changing, it controls so that the temperature detection value of the temperature sensor 39 and the infrared sensor 32 may correspond early. Thereby, the temperature detection error by the difference in the infrared radiation rate depending on the sled of the pan bottom of the pan as the cooking utensil 35, the material of the pan, and the surface state can be reduced. Therefore, even if it uses the cooking utensils from which a material and a shape differ, desired heating control can be performed and the improvement of the cooking performance as an induction heating cooking appliance can be aimed at.

  The graph of FIG. 21 shows that the temperature rise value per kW · s is 0.6 ° C. in the iron pan as the standard pan, whereas the temperature rise is easy in the case of the SUS pan. Shows a temperature rise of 0.2 ° C., and the SUS pan 4 shows a temperature rise of about 0.4 ° C. Therefore, for example, the upper limit value of the infrared target temperature is variably set according to the difference in the rate of temperature increase. If the upper limit of the infrared target temperature for an iron pan (set as a standard pan) is set to 200 ° C, change it to 170 ° C for SUS pan 1, and change it to 180 ° C for SUS pan 4. In the case of the SUS pan 7, the temperature is changed to 195 ° C.

  Subsequently, it is determined whether or not the pan is a small pan (step S116). If it is a small pan, the Max power of the heating power is reduced to 1 kW (step S117). However, if the small pan determination is not made, the heating control is continued so as to reach the corrected infrared target temperature. The determination of the small pan is determined to be a small pan when the integrated power amount in step S114 is extremely smaller than a predetermined reference value, that is, when the heat capacity of the cooking utensil 35 is small.

  By limiting the heating power Max to 1 kW based on the determination of the small pan, it is possible to prevent a rapid temperature rise caused by emptying a small pan having a small heat capacity or a SUS frying pan.

  When the cooking utensil 35 is heated and the cooked product is put into the cooking utensil 35 and the temperature of the cooking utensil 35 is lowered at once, the heating power set value is increased at once according to the data series based on the temperature Tpu. Control to do. The appropriate temperature detection in this case will be described with reference to the flowchart of FIG. The flowchart in FIG. 17 is repeated as a routine once per second, for example. First, the infrared target temperature is converted into an infrared target AD value (step S101). The infrared temperature and the infrared output AD value are converted based on, for example, the correspondence between the Tpu temperature ° C and the Vto output voltage mV shown in FIG. However, since it changes according to the characteristics of the equipment, the conversion data is registered in the thermal power control device 41 for each equipment.

  Next, it is determined whether or not the infrared measurement AD value in the current routine has reached a certain range and within ± 5 with respect to the infrared target AD value (step S102). If not within this range, the count value Cnt of the appropriate temperature notification counter is reset to 0 (step S103).

  If the result of determination in step S102 is within the range of ± 5, it is next determined whether or not the infrared measurement AD value in this routine has changed within the previous infrared measurement AD value within ± 1. Determination is made (step S104). Again, if the change in the infrared measurement AD value is not within the range of ± 1, the count value Cnt is reset to 0 (step S103).

  If this change is within ± 1, then, the count value Cnt of the appropriate temperature notification counter is incremented by 1, and Cnt ← Cnt + 1 is set (step S105). Then, it is determined whether or not the count value Cnt ≧ 25 is satisfied (step S106). That is, it is determined whether or not the infrared measurement AD value continues within 25 seconds for the infrared target AD value and the time change of the infrared measurement AD value has settled within ± 1 / sec.

  If it is determined in step S106 that the infrared measurement AD value has not yet reached a stable state for 25 seconds, the routine proceeds to the next routine while maintaining the count value Cnt of the appropriate temperature notification counter (step S106). Branch off to NO).

  On the other hand, if it is determined in step S106 that Cnt ≧ 25, the process branches to YES and notification of reaching the appropriate temperature is notified (step S107). The appropriate temperature notification is displayed on the display unit or notified by a buzzer.

  Further, as shown in FIG. 18, it is possible to change the heating power setting value according to the temperature rise control table according to the detection output of the infrared sensor 32 according to the result of the appropriate temperature detection. In other words, the slope of the infrared proportional control data before detection of the appropriate temperature can be set to a gentle and insensitive setting of 30, and after the detection of the appropriate temperature, the inclination of the infrared proportional control data can be set to be as steep as 20 and changed to a sensitive setting. As a result, the heating power is strengthened during the temperature rise control before reaching the appropriate temperature, and the set temperature can be accurately maintained after reaching the appropriate temperature.

  As described above, according to the present embodiment, the thermal power control device 41 controls the thermal power by the heating means 48 according to the detection output of the temperature sensor 39 during the period when the temperature of the cooking utensil 35 rises. While setting (1) to (9), according to the detection output of the infrared sensor 32 (the entire detection output Vto that does not exclude the detection output Vpu of the infrared sensor 32 corresponding to the radiation energy from the lower surface of the top plate 16) Thus, the heating power set value according to the set data series is determined from the data series (1) to (9). Therefore, the set values of the data series (1) to (9) set according to the detection output without reducing the detection output of the infrared sensor 32 and eliminating the information contained in the detection output without using it. Therefore, even when the heat capacity of the cooking utensil 35 is small, the degree of temperature increase can be controlled with high accuracy, and an excessively high temperature state can be reliably prevented.

  Moreover, since the thermal power control device 41 also sets a data series (10 ′) for controlling the thermal power by the heating means 48 in accordance with the detection output of the temperature sensor 39, the situation of the cooking utensil 35 and the temperature sensor 39 are also set. By performing proportional control according to the detection output, the reliability of control and cooking performance can be improved.

  In addition, since the thermal power control device 41 sets the data series (9) and the data series (10 ′) to the upper limit values, the thermal power control apparatus 41 is overheated by both the detection output of the infrared sensor 32 and the detection output of the temperature sensor 39. The temperature prevention function can be applied, and temperature monitoring can be performed twice. In particular, when the temperature detected by the temperature sensor 39 is higher than the temperature Tpu (220 ° C.) corresponding to the data series (9), it can be shifted to the data series (10 ′) so as to be higher than the former thermal power output upper limit value. The latter upper limit of thermal power output was set high. As a result, even when infrared rays cannot be detected properly by the infrared sensor 32, it is possible to control based on the temperature sensor 39 as a suboptimal overheat prevention function, and thus safer cooking is possible.

  Since the data series (1) to (9) are set as data for proportionally controlling the heating power P in accordance with the detection output of the infrared sensor 32, for example, the temperature of the cooking utensil 35 rapidly rises during frying pan cooking. Even if this is assumed, the overheat prevention function can be realized with high accuracy.

  Moreover, even in the case of preheating with oil in a frying pan or cooking fried food with a small amount of oil such as a cutlet, it is possible to suppress a sudden rise in the oil temperature and to reliably prevent overheating. At the same time, even when using a pan at the bottom of the pan or a pan with a different infrared radiation rate, it is possible to accurately notify the proper temperature at which tempura cooking can be started and to notify the completion of preheating of frying pan cooking.

  Furthermore, even if it uses the cooking utensil from which a material and a shape differ, desired heating control can be performed and the improvement of the cooking performance as an induction heating cooking appliance can be aimed at. In addition, by determining a pot or a small pan having a small heat capacity, the maximum heating power can be reduced to prevent a rapid temperature increase caused by emptying a small pot having a small heat capacity or a SUS frying pan.

  In addition, in the appropriate temperature notification control, by changing the setting value of the temperature rise control table according to the detection output of the infrared sensor 32, preheating with oil in a frying pan or cooking of fried food with a small amount of oil such as cutlet Even in this case, it is possible to prevent an overshoot due to a sudden rise in the oil temperature, and at the same time, it is possible to quickly recover the thermal power against a temperature drop at the time of frying pan cooking or tempura cooking utensil addition, and the cooking performance can be improved.

[Water heating control example 1]
Then, the boiling water control by the induction heating cooking appliance 2 of this Embodiment is demonstrated. The prior art disclosed in Patent Document 3 (Japanese Patent No. 4321278) uses a photodiode as an infrared sensor for the purpose of not detecting the radiation of the glass top plate 1. Since the detection wavelength of light of the photodiode is 1 μm or less, glass radiation is hardly detected. However, to detect boiling, the temperature at the bottom of the pan is substantially equal to the boiling temperature, which is about 100 ° C. In this temperature state of 100 ° C., the radiation of light having a wavelength of 1 μm or less is very small, which is almost the same. That is, the maximum radiation wavelength λm of a black body at 100 ° C. is 7.8 μm, and the spectral radiation energy Ebλm at this maximum radiation wavelength λm is 93 W / μ · m ² . However, the spectral radiation energy Ebλ of 1 μm of a black body at 100 ° C. is 0.67 × 10 ⁻⁸ W / μ · m ² , which is 1/10 billion or less of Ebλm. On the other hand, the spectral radiant energy Ebλ of 2.7 μm at which the spectral transmittance of the glass greatly changes is 1.6 W of Ebλm at 1.5 W / μ · m ² . Ebλ of 1 μm is extremely small, less than 1/100 million, even compared to Ebλ of 2.7 μm. (Μ in the unit of spectral radiant energy W / μ · m ² is μm).

  On the other hand, sunlight and light from an incandescent bulb contain many wavelengths of 1 μm or less due to spectral radiation equivalent to several thousand degrees. Therefore, these become disturbance light and are detected by the photodiode. For this reason, accurate temperature detection cannot be performed even if boiling detection of water or the like is performed by temperature detection. Further, since the enamel pan has substantially the same spectral radiation characteristics as glass, the spectral emissivity in the vicinity of 1 μm is very small, and it is difficult to detect radiation of the enamel pan using a photodiode, resulting in poor detection accuracy.

  According to the present embodiment, by using an infrared sensor such as a thermopile that can detect a wide range of infrared rays including infrared rays having a long wavelength of 2.7 μm or more as the infrared sensor 32, the radiation of the glass top plate 16 is used. Also detect.

  Radiant energy that contributes to temperature detection of the top plate 16 has a larger amount of energy than disturbance light energy caused by sunlight or light from an incandescent bulb. For this reason, the influence by the disturbance light energy by sunlight or the light of a light bulb becomes small. Further, glossy metals such as those made of SUS have a low emissivity, and thus the radiant energy is also low.

  However, in the present embodiment, the infrared sensor 32 also detects radiation from the upper surface of the top plate 16, and this radiation energy is also used for temperature detection. Good boiling detection is possible.

  On the other hand, the radiation from the lower surface of the glass top plate 16 and the difference in the emissivity of the pan cause error. Therefore, in the boiling water control according to the present embodiment, temperature detection processing is performed so that detection errors due to these error factors are eliminated and accurate boiling detection can be performed.

  The infrared sensor 32 is disposed below the glass top plate 16, detects the amount of infrared radiation radiated from the glass top plate 16 and the object to be heated 35, and outputs it to the thermal power control device 41. The thermal power control device 41 controls the thermal power of the heating means 48 by detecting the detection value of the infrared sensor 32 and its rate of change.

  In this case, the thermal power control device 41 compares the spectral radiation detection characteristic of the infrared sensor 32 with the radiation energy of a pan having a pan bottom with an emissivity of approximately 100% in the infrared region, and detects the radiation energy of glass more. Boiling is detected by the detection value of the infrared sensor 32, and the load amount of the pan is detected by the detection value of the infrared sensor 32 at the time of boiling detection and the rate of change of the detection value of the infrared sensor 32 before the detection of boiling. The heating power of the heating means 48 is controlled accordingly.

  22 and 23 show the temperature detection results by the infrared sensor 32 in the present embodiment. FIGS. 22 (a) and 22 (b) show the transition of the control result at the time of boiling water with a water volume of 0.5L, the detection result of the infrared sensor 32, and the infrared detection value change rate. FIGS. 23 (a) and 23 (b) The control result at the time of boiling water with a water volume of 1.5 L, the detection result of the infrared sensor 32, and the transition of the infrared detection value change rate are shown. Further, Ttod and ΔTtod / Δt are those of the enamel pan, and Ttos and ΔTtos / Δt are those of the SUS pan. Of the suffixes, “d” represents an enamel pan and “s” represents an SUS pan.

  When heating is started with an input of 1.5 kW, the rate of change in the detected value gradually increases with an increase in the amount of received infrared light, and thereafter increases at a substantially constant rate of change. If the temperature rises to near the boiling point, the change in the infrared detection value becomes gradual and the change rate decreases. At the times tba1 and tbb1, the change rates of the detection values Ttod and Ttos of the infrared sensor 32 are set in advance. When it becomes equal to or less than the predetermined value Ts2, boiling is detected, and the input is reduced to 200 W at time tba2 and tbb2 after a predetermined time, and the temperature is kept.

  As shown in the graphs of FIGS. 22 and 23, the detection value of the infrared sensor 32 varies depending on the shape of the pan bottom and the radiation rate. That is, in the case of the enamel pan, the conversion value 95 ° C. of the detection value Ttod of the infrared sensor 32 corresponds to 100 ° C. of the boiling temperature, and in the case of the SUS pan, the conversion value 65 ° C. of the detection value Ttos is 100 ° C. of the boiling temperature. It corresponds to. Therefore, for example, in the case where boiled noodles are used and heating is continued with medium heat so as not to blow down, the control temperature Tsk after the boiling detection is 95% of the temperature detection value Tb of the infrared sensor 32 at the boiling temperature detection time, that is, , Tsk = 0.95 × Tb is set as the set temperature. Further, when the temperature is kept at 80 ° C., similarly, Tsk = 0.80 × Tb is set as the set temperature.

  As described above, the temperature detection value of the infrared sensor 32 at the boiling detection times tba1 and tbb1 corresponds to 100 ° C. Therefore, if the temperature setting after the boiling detection is performed at a predetermined ratio of the detection value, the dent and material of the pan bottom Thus, temperature control with high accuracy is possible even in pans with different shapes and radiations, and stewed cooking without fear of spilling and accurate heat retention control are possible.

  FIG. 24 is a flowchart of the hot water control described above. In the following description of each flowchart and description of each control example, Ttod is used as a representative example, but Ttos is the same. In step S201, induction heating is started by starting heating. In step S203, it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds a predetermined value Ts1 set in advance. If it does not exceed, it will transfer to NO and will continue heating. If it exceeds, the process proceeds to YES, and it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds the upper limit value of the temperature rise control data series (step S205). If it exceeds, the temperature rise control data series is switched and induction heating is continued.

  If the detection value Ttod of the infrared sensor 32 does not exceed the upper limit value of the temperature rise control data series in step S205, the process branches to YES, and it is determined whether or not the change rate ΔTtod / Δt of Ttod is equal to or less than a predetermined value Ts2. (Step S207).

  By the determination in step S207, it can be determined that the rate of increase is dull after the temperature increase by the constant rate of increase and the rate of change ΔTtod / Δt approaches 0 and approaches the boiling temperature. If the determination here is NO, induction heating is continued.

  If “YES” in the step S207, the boiling is detected, and after a predetermined time, the output is reduced to a predetermined value, for example, 200 W, and kept warm.

  Thereafter, the process proceeds to step S209, and the detection value Ttod of the infrared sensor 32 at the time of boiling determination is regarded as a value corresponding to 100 ° C. and stored as Tb. Further, the control temperature Tsk after boiling is obtained by Tsk = k · Tb with respect to the detection value Tb corresponding to 100 ° C. However, k = target set temperature / 100. And Ttod is controlled so that it may become this control temperature Tsk (step S211-S217). This temperature control is continued until the end of heating is input (steps S219 and S221).

  In this way, in the case of simple hot water boiling, for so-called calcination, after the boiling is detected, the heating power is reduced and, for example, the boiling temperature is maintained for 5 minutes, and then the boiling alarm is issued. Further, in the case of stewed cooking, it is possible to control to continue the boiling temperature by reducing the heating power only during the set stew maintenance time, and thereafter issue a stew completion alarm. For example, when the temperature is maintained at 95 ° C., the thermal power control is performed by setting Ttod such that Tsk = (95/100) × Tb.

  According to the boiling water control 1, the infrared sensor 32 has a spectral detection characteristic that detects a part of the spectral radiation of the glass, and detects infrared radiation from the pan and from the top surface of the top plate 16. The light receiving energy of 32 becomes large, and a temperature as low as about 100 ° C. can be easily detected.

  In order to simplify the control, it is not determined that Ttod is the detection value predetermined value Ts1 ≧, and the detection value of the infrared sensor 32 is the upper limit value of the temperature rise control data series (1) to (10). It is good also as what detects below that the detection value change rate of the infrared sensor 32 is below change rate predetermined value Ts2, and detects boiling.

[Water heater control example 2]
The boiling water control of Control Example 2 will be described using the graphs of FIGS. 22 and 23 and the flowchart of FIG. In this control example 2, the change rate ΔTtod / Δt of the detection value by the infrared sensor continues for a predetermined time Hr, for example, 2 minutes or more (this time is appropriately set), the change rate first predetermined value Ts2 ′ (this example) In this case, Ts2 ′ = the change rate predetermined value Ts2 used in Control Example 1. This value can be set to a value different from Ts2, and then the change rate second predetermined value Ts2 (Control Example 1). It is characterized by a control for detecting boiling when the rate of change in a predetermined value is less than a predetermined value.

  Immediately after the first cooking, when the pan is removed and a pan containing cold water is set for another second cooking and heating is started, the temperature of the pan rises but the temperature of the top plate 16 falls. For this reason, immediately after the start of heating, the detection value of the infrared sensor 32 once decreases and then increases. While the detected value decreases, the detected value change rate ΔTtod / Δt may be small, and according to the control example 1 that performs simple boiling detection, it may be impossible to accurately detect boiling. Similarly, when the cooking conditions change, such as when a cold cooking object or water is added while the top plate 16 is hot during cooking, the detection value of the infrared sensor 32 once decreases and then increases. Therefore, during this time, the rate of change may be small, and there is a risk that boiling may be detected by mistake. In this control example 2, the boiling detection is accurately performed even when the heating condition changes in this way.

  In step S251, induction heating is started by starting heating. In step S253, it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds a predetermined value Ts1 set in advance. If it does not exceed, it will transfer to NO and will continue heating. And if it exceeds, it will transfer to YES and it will be determined whether the detection value Ttod of the infrared sensor 32 has exceeded the upper limit of a temperature rise control data series (step S255). If it exceeds, the temperature rise control data series is switched and induction heating is continued.

  If the detected value Ttod of the infrared sensor 32 does not exceed the upper limit value of the temperature rise control data series in step S255, the process branches to YES, and whether or not the change rate ΔTtod / Δt of Ttod is equal to or higher than the change rate first predetermined value Ts2 ′. Is determined (step S257).

  If NO in this step S257, it can be considered that the water temperature tw has not sufficiently increased in heating, and heating is continued. On the other hand, if “YES” in the step S257, the water temperature tw can be regarded as rising, so the duration Ht in which the detection value change rate exceeds the first predetermined value Ts2 ′ is measured and the heating is continued. (Step S259).

  If the water temperature tw rises to near the boiling temperature due to the continuation of this heating, the rate of increase is dull. Then, the detected value change rate ΔTtod / Δt decreases. When this rate of change decreases, the determination in step S257 branches to NO, and in the subsequent step S261, the detected value change rate ΔTtod / Δt becomes the second predetermined value Ts2 of the detected change rate (the change rate predetermined value in Control Example 1). It is determined whether or not the value is smaller than the same value.

  By the determination in step S261, it can be determined that the rate of increase is dull after the water temperature has increased and the rate of change ΔTtod / Δt has approached 0 and has approached the boiling temperature. If the determination here is NO, induction heating is continued.

  If the determination in step S261 is YES, it is determined whether or not the duration Ht that is equal to or greater than the first predetermined value Ts2 ′ of the change rate exceeds the comparison set time Hr (step S263). If the duration time Ht exceeds the predetermined time Hr, it is determined that the rate of increase has slowed after a sufficient increase in heating, and boiling detection is performed (branch to YES in step S263).

  If boiling is detected in step S263, the process proceeds to step S265, and the detection value Ttod of the infrared sensor 32 at the time of boiling determination is regarded as a value corresponding to 100 ° C. and stored as Tb. Further, the control temperature Tsk after boiling is obtained by Tsk = k · Tb with respect to the detection value Tb corresponding to 100 ° C. (step S267). However, k = target set temperature / 100. Then, Ttod is controlled to reach this control temperature Tsk (steps S269 to S273). This temperature control is continued until the end of heating is input (steps S275 and S277). The control in steps S265 to S277 is the same as that in steps S209 to S221 in Control Example 1.

  According to this water heating control example 2, in addition to the effect of the control example 1, as described above, immediately after the first cooking, the pan is removed and a pan containing cold water is set for another second cooking. Start cooking, such as when the temperature of the pan rises but the temperature of the top plate 16 falls, or when the top plate 16 gets hot during cooking, put cold food or water As in the case where the conditions change, boiling detection can be performed with high accuracy even under heating conditions in which the detection value of the infrared sensor 32 temporarily decreases and then increases.

[Water heater control example 3]
The boiling water control of Control Example 3 will be described using the graphs of FIGS. 26 and 27 and the flowchart of FIG. The control example 3 compares the spectral radiation detection characteristic of the infrared sensor 32 with the radiation energy of a pot having a pan bottom with an emissivity of approximately 100% in the infrared region, and has a characteristic of detecting more radiation energy of glass. the use, detection values TTOD of the infrared sensor 32 is a predetermined value Ts1 or more, and detects that the detection value change rate change Δ ² Ttod / Δt ² of the infrared sensor 32 is a negative rate of change changes by a predetermined value Ts3 less It is characterized by detecting boiling. In order to simplify the control, the determination in step S253 as to whether or not the detection value is equal to or greater than the predetermined value Ts1 can be omitted.

The infrared sensor 32 detects infrared energy obtained by adding the infrared rays of the pan 35 and the top plate 16, but the temperature rise of the top plate 16 is delayed from that of the pan 35. On the other hand, the temperature rise of the pan 35 changes depending on the amount of water in the pan 35, the shape of the bottom of the pan, and the like. That is, if the amount of water is large and the pan bottom is concave, boiling detection tends to be delayed, and if the amount of water is small and the pan bottom is flat, the boiling detection tends to be accelerated. Therefore, this control example 3 detects boiling when the detected value change rate change Δ ² Ttod / Δt ² of the infrared sensor 32 is equal to or less than the negative predetermined value Ts3, thereby boiling due to the amount of water in the pan, the shape of the pan bottom, or the like. Reduces detection errors and performs accurate boiling detection.

  Assume that immediately after the first cooking, the pan is removed, a pan containing cold water is set for another second cooking, and heating is started. In this case, the temperature of the pan rises, but the temperature of the top plate falls. Therefore, immediately after the start of heating, the detection value of the infrared sensor 32 once decreases and then increases. Even in the case of such reheating, since the change rate change does not become negative, unlike the control example 1, the boiling is not erroneously detected.

FIGS. 26 (a), (b), and (c) show the control results when boiling water of 0.5 L and the detection results of the infrared sensor 32, respectively. FIGS. 27 (a), (b), and (c) The control result and the detection result of the infrared sensor 32 at the time of boiling water of 1.5 L are respectively shown. Ttod is the detection result in the enamel pan, and Ttos is the detection result in the SUS pan. ΔTtod / Δt is the rate of change of Ttod, Δ ² Ttod / Δt ² is the rate of change of Ttod, ΔTtos / Δt is the rate of change of Ttos, and Δ ² Ttos / Δt ² is the rate of change of Ttos.

When heating is started at an input of 1.5 kW, the water temperature tw rises and becomes equal to or greater than the detection predetermined value Ts1 at times tbc0 and tbd0, respectively. By continuing heating thereafter, the change rate change Δ ² Ttod / Δt ² and Δ ² Ttos / Δt ² of the detection values Ttod and Ttos of the infrared sensor 32 change from 0 to negative at times tbc1 and tbd1. Since the predetermined value Ts2 of rate change is reached, boiling is detected at this time. At times tba2 and tbb2 after a predetermined time, the input is reduced to 200 W and the temperature is controlled.

  A control example 3 will be described with reference to the flowchart of FIG. Here again, Ttod will be described as a representative. The same applies to other control examples. In step S301, induction heating is started by starting heating. In step S303, it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds a predetermined value Ts1 set in advance. If it does not exceed, it will transfer to NO and will continue heating. If it exceeds, the process proceeds to YES, and it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds the upper limit value of the temperature rise control data series (step S305). If it exceeds, the temperature rise control data series is switched and induction heating is continued.

In step S305, the detection value TTOD is branched to YES does not exceed the upper limit value of the temperature increase control data sequence, the change rate of change ΔTtod / Δt of TTOD, namely Δ ² Ttod / Δt ² is the rate of change of the infrared sensor 32 It is determined whether or not the change is less than or equal to a predetermined value Ts3 (negative value) (step S307).

If NO in this step S307, it can be assumed that the water temperature tw has not been sufficiently heated and heating is continued. On the other hand, if YES in step S307, boiling detection is performed. That is, if the water temperature tw rises to near the boiling temperature due to continued heating, the rate of increase is dull. Then, the detected value change rate ΔTtod / Δt decreases. If this rate of change decreases, the rate of change change becomes a negative value. Accordingly, it is determined that the rate of change Δ ² Ttod / Δt ² has become equal to or less than a predetermined value Ts3.

  If boiling is detected in step S307, the process proceeds to step S309, and the detection value Ttod of the infrared sensor 32 at the time of boiling determination is regarded as a value corresponding to 100 ° C. and stored as Tb. Further, the control temperature Tsk after boiling is obtained by Tsk = k · Tb with respect to the detection value Tb corresponding to 100 ° C. (step S311). However, k = target set temperature / 100. Then, Ttod is controlled to reach this control temperature Tsk (steps S313 to S317). This temperature control is continued until the end of heating is input (steps S319 and S321). The control in steps S309 to S321 is the same as that in steps S209 to S221 in Control Example 1. In order to simplify the control, it is possible to omit the determination of the detected value not less than the predetermined value Ts1 in step S303.

  When boiling, the temperature at the bottom of the pan becomes substantially constant, but the temperature at the top surface of the top plate 16 rises due to radiation and heat conduction from the pan bottom, and the heat capacity of the top plate 16 and heat conduction to the back surface of the top plate are increased. Therefore, the temperature rise of the top plate 16 is delayed from the pan, and the temperature rise continues even after the pan reaches a certain temperature due to boiling. However, at this time, since the temperature of the pan is substantially constant and does not rise, the curve of the temperature rise of the top plate 16 becomes dull.

  As described above, when boiling, the temperature rise of the pan becomes constant and the temperature rise curve of the top plate 16 becomes dull. Consequently, the temperature rise curve of the temperature detection value Ttod of the infrared sensor 32 becomes gentle at the boiling time, and the rate of change Changes. On the other hand, the rise in the temperature of the pan changes depending on the amount of water in the pan, the shape of the bottom of the pan, etc. Therefore, if boiling is detected at a predetermined rate of change, an error occurs. That is, when the amount of water is large, or when the pan bottom is concave and the pan bottom is separated from the top plate, the boiling detection is delayed. On the other hand, if the amount of water is small and the bottom of the pan is flat, boiling detection is accelerated.

In this control example 3, the temperature rise curve of the temperature detection value of the infrared sensor 32 becomes gentle at the boiling time, and the time when the rate of change changes, that is, Δ ² Ttod / Δt ² of the detection value Ttod of the infrared sensor 32 is negative. Since boiling is detected when the predetermined value Ts3 is reached, there is little boiling detection error due to the amount of water in the pot, the shape of the pot bottom, etc., and boiling detection can be performed with high accuracy.

Further, according to the control example 3, it is possible to accurately detect boiling even in the case of reheating. That is, about the detection result at the time of reheating control of FIG. 29 (a), (b), (c), immediately after the first cooking, the pan is removed, and a pan containing cold water is used for another second cooking. When heating is started after setting, the temperature of the pan rises, but the temperature of the top plate 16 decreases. Immediately after the start of heating, the detection value Ttod of the infrared sensor 32 once falls below the detection value predetermined value Ts1, and thereafter To rise. When the water temperature is lowered, the change rate ΔTtod / Δt becomes the change rate predetermined value Ts2 or less at the initial stage of reheating. However, the change rate change Δ ² Ttod / Δt ² does not become negative. For this reason, according to the present control example 3 in which boiling detection is performed when the change in change rate Δ ² Ttod / Δt ² becomes equal to or less than the negative predetermined value Ts3 after detecting the predetermined detection value Ts1, the boiling is erroneously detected. Without detecting it, boiling can be detected accurately.

[Water heater control example 4]
In the control example 4, if the temperature detection value change rate change once becomes 0 or a negative value and then becomes a positive value, then it is detected that the temperature has become equal to or less than a predetermined negative value Ts3 and then boiling is detected. It is characterized by that.

FIG. 30 shows a detection example in which the pan is heated to 70 ° C. before boiling with another heat source, for example, the induction heating unit on the right side, and then the pan is moved to the induction heating unit on the left side, and after a while, it is reheated. Show. In this case, the temperature of the back surface of the top plate 16 decreases for a while after starting heating in the left induction heating unit. Therefore, immediately after the heating start time tst, the change rate change Δ ² Ttod / Δt ² of the detection value of the infrared sensor 32 becomes negative, and in the case of boiling water control according to the control example 3, there is a possibility that boiling is erroneously detected. Such erroneous detection may occur even under other heating conditions. That is, when the heating power is reduced during heating or when cold water is added during heating, the change rate change Δ ² Ttod / Δt ² once becomes a negative value. On the other hand, when the boiling is not actually performed in this way, the detected value Ttod increases immediately after the change rate change Δ ² Ttod / Δt ² becomes a negative value, and the change rate change Δ ² Ttod / Δt ² is a positive value. It becomes.

Therefore, in the present control example 4, if the change rate change Δ ² Ttod / Δt ^{2 of} the temperature detection value Ttod becomes 0 or a negative value and then becomes a positive value, it is not regarded as boiling detection, and thereafter By detecting boiling when the negative predetermined value Ts3 or less is reached, boiling is accurately detected even under such heating conditions.

  A control example 4 will be described with reference to the flowchart of FIG. In step S351, induction heating is started by starting heating. In step S353, it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds a predetermined value Ts1 set in advance. If it does not exceed, it will transfer to NO and will continue heating. And if it exceeds, it will transfer to YES and it will be determined whether the detection value Ttod of the infrared sensor 32 has exceeded the upper limit of a temperature rise control data series (step S355). If it exceeds, the temperature rise control data series is switched and induction heating is continued.

If the detection value Ttod of the infrared sensor 32 does not exceed the upper limit value of the temperature rise control data series in step S355, the process branches to YES, and the change in the change rate of Ttod ΔTtod / Δt, that is, Δ ² Ttod / Δt ² is 0 or It is determined whether or not it has become a positive value after it has become a negative value (step S357).

  If YES in step S357, heating is continued. On the other hand, if the change in change rate continues to be a positive value, the process branches to NO and proceeds to step S359.

In step S359, the temperature rises to near the boiling temperature and the detected value change rate ΔTtod / Δt decreases. If the change rate change Δ ² Ttod / Δt ² is equal to or less than the predetermined value Ts3, boiling is detected. If it is higher than the predetermined value, heating is continued.

  If boiling is detected in step S359, the process proceeds to step S361, and the detection value Ttod of the infrared sensor 32 at the time of boiling determination is regarded as a value corresponding to 100 ° C. and stored as Tb. Further, the control temperature Tsk after boiling is obtained by Tsk = k · Tb with respect to the detection value Tb corresponding to 100 ° C. (step S363). However, k = target set temperature / 100. Then, Ttod is controlled to reach this control temperature Tsk (steps S365 to S369). This temperature control is continued until the end of heating is input (steps S371 and S373). The control in steps S361 to S373 is the same as that in steps S209 to S221 in Control Example 1. In order to simplify the control, it is possible to omit the determination of the detected value not less than the predetermined value Ts1 in step S353.

  In the boiling water control example 4, in addition to the effect of the control example 3, when the temperature change rate change once becomes a negative value at the start of heating, at the time of restarting heating, at the time of variable heating power setting, at the time of pouring cold water in the middle of heating, etc. Even if there is, there is no false detection of boiling, and accurate boiling detection is possible.

[Water heater control example 5]
A water heating control example 5 will be described with reference to the flowchart of FIG. This control example 5 detects that the change rate change Δ ² Ttod / Δt ² of the detection value Ttod by the infrared sensor 32 is the negative first predetermined value Ts3 in the graph of FIG. Boiling detection is performed at time tbd3 by detecting that the predetermined value Ts4 or less has continued for a predetermined time Ht or longer.

  In Control Example 5, induction heating is started by starting heating in step S401. In step S403, it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds a predetermined value Ts1 set in advance. If it does not exceed, it will transfer to NO and will continue heating. If it exceeds, the process proceeds to YES, and it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds the upper limit value of the temperature rise control data series (step S405). If it exceeds, the temperature rise control data series is switched and induction heating is continued.

If the detection value Ttod of the infrared sensor 32 does not exceed the upper limit value of the temperature rise control data series in step S405, the process branches to YES, and the change in the change rate of Ttod ΔTtod / Δt, that is, Δ ² Ttod / Δt ² is 0 or It is determined whether or not a positive value is reached after the negative value is reached (step S407). If it becomes a positive value after a negative value, the process branches to YES and heating is continued. On the other hand, if the negative value continues or the positive value continues, the process branches to NO and proceeds to step S409.

In step 409, it is determined whether or not the change rate change Δ ² Ttod / Δt ² is equal to or less than a predetermined value Ts3. If the temperature rises to near the boiling temperature, the rate of temperature rise becomes dull, and the detected value change rate ΔTtod / Δt decreases, so that the change rate change becomes a negative value. Again, if it is greater than the first predetermined value Ts3, the process branches to NO and heating is continued. On the other hand, if the change in change rate is equal to or less than the negative first predetermined value Ts3, the process branches to YES and proceeds to step S411 for boiling detection determination.

  If the temperature rise of the water temperature tw is smooth, the rate of change in temperature does not fluctuate greatly before and after the time when the rate of change in temperature becomes dull and the value of change in rate of change becomes negative. Therefore, if the change rate change is equal to or less than the negative first predetermined value Ts3, in step S411, it is determined whether or not the duration during which the change rate change is equal to or less than the second predetermined value is the predetermined time Ht. If YES, boiling is detected.

  If boiling is detected in step S411, the process proceeds to step S413, and the detection value Ttod of the infrared sensor 32 at the time of boiling determination is regarded as a value corresponding to 100 ° C. and stored as Tb. Further, the control temperature Tsk after boiling is obtained by Tsk = k · Tb with respect to the detection value Tb corresponding to 100 ° C. (step S415). However, k = target set temperature / 100. Then, Ttod is controlled to reach this control temperature Tsk (steps S417 to S421). This temperature control is continued until the end of heating is input (steps S423 and S425). The control in steps S413 to S425 is the same as that in steps S209 to S221 in Control Example 1. In order to simplify the control, it is possible to omit the determination of the detected value not less than the predetermined value Ts1 in step S403.

  In this boiling water control example 5, in addition to the effect of the control example 3, the temperature change rate change may once become a negative value when heating is started, when heating is restarted, when the heating power setting is variable, or when cold water is poured during heating. Even if it exists, it is possible to detect boiling with high accuracy without erroneously detecting boiling.

[Water heater control example 6]
FIG. 33 shows a time-series change in the pan bottom temperature Tpb, the water temperature tw, the infrared sensor detection value Ttod, and the temperature change rate of the infrared sensor detection value Ttod.

  In the IH heating, since an induced current flows through the pan bottom, only the pan bottom is heated. On the other hand, soups such as miso and soup have a high viscosity, so that convection hardly occurs, and the heat at the bottom of the pan is not easily taken away by the soup. Therefore, as shown in FIG. 33 (a), the rise in the pan bottom temperature Tpb is fast and fast, but the rise in the water temperature tw near the middle of the water surface of the soup in the pan and the pan bottom is slow. The detection value Ttod of the infrared sensor detects the pan bottom temperature Tpb and the infrared rays radiated from the top plate 16 in contact with the pan bottom, and therefore rises faster than the water temperature tw in the same manner as the pan bottom temperature Tpb rises. Therefore, even if the infrared sensor detection value Ttod is the boiling temperature, the contents of the pan may not reach the boiling temperature.

  Therefore, in the control example 6, in the determination of whether or not the change rate ΔTtod / Δt of the Ttod in the control example 1 is equal to or less than the change rate predetermined value Ts2 (step S207 in FIG. 24), Is reduced from 1.5 kW to 0.5 kW (= Pl), the actual water temperature tw is calculated by looking at the rate of decrease in the pan bottom temperature Tpb, and boiling is detected.

  More specifically, when the change rate ΔTtod / Δt of the detection value Ttod becomes equal to or less than the predetermined value Ts2, the thermal power P is reduced from 1.5 kW to 0.5 kW (= Pl) during the predetermined period δt1 from time tf1 to time t2. .

  During the predetermined period of δt1, the amount of heat generated at the pan bottom decreases, and the amount of heat released by convection does not change, so the pan bottom temperature Tpb decreases. The speed at which the pan bottom temperature Tpb decreases correlates with the water temperature tw, and is slow if the water temperature tw is high and fast if the water temperature tw is low. Therefore, the water temperature tw is determined by the change rate of the detection value Ttod of the infrared sensor during the period δt1. Calculate. Infrared sensor detection value Ttod change (decrease) δTt in the state where thermal power P is once lowered to Pl is large, and if it is greater than or equal to a predetermined value, it is considered that the water temperature tw has not yet reached the boiling temperature, and the thermal power P is Increase to 1.5 kW and continue heating. And this control is repeated as long as the water temperature fall rate at the time of a thermal power fall is larger than a predetermined value.

  When the water temperature tw reaches 100 ° C., the change δTt5 of Ttod becomes equal to or less than the predetermined value at time to6 when the predetermined period δt5 has elapsed after time tf5. By detecting this, boiling is detected, and then heat insulation control is performed.

  34 will be described with reference to the flowchart of FIG. In step S501, induction heating is started by starting heating. In step S503, it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds a predetermined value Ts1 set in advance. If it does not exceed, it will transfer to NO and will continue heating. If it exceeds, the process proceeds to YES, and it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds the upper limit value of the temperature rise control data series (step S505). If it exceeds, the temperature rise control data series is switched and induction heating is continued.

  If the detection value Ttod of the infrared sensor 32 does not exceed the upper limit value of the temperature rise control data series in step S505, the process branches to YES, and it is determined whether or not the Ttod change rate ΔTtod / Δt has become equal to or less than the predetermined value Ts2. (Step S507). Since the values of Ts1 and Ts2 are the same as Ts1 and Ts2 in FIG. 22, they are omitted in FIG.

  If NO in this step S507, induction heating is continued. In the case of YES in step S507, the thermal power P is reduced from the thermal power 1.5 kW during heating to 0.5 kW (= Pl) (step S511). Then, it is determined whether the predetermined time δts has elapsed from the time δt after the thermal power is set to 0.5 kW (step S513). If the elapsed time δt is less than δts in step S513, the process waits until δt becomes δts.

  In step S513, when the elapsed time δt after the decrease in the thermal power reaches the predetermined time δts, the thermal power is reduced by the change δTti (i is a variable 1, 2, 3,...) Of the detected value Ttod by the infrared sensor during the δt period. It is determined whether or not the absolute value divided by the detection value Tti (i is a variable 1, 2, 3,...) Detected by the previous infrared sensor is smaller than the predetermined change value kts. That is, it is determined whether or not | δTti / Tti | ≦ kts (step S515). Note that Tt = Ttod.

  In the case of NO in step S515, it is considered that the water temperature decrease rate or the decrease degree during the thermal power decrease is large and the boiling has not been reached, and the thermal power is increased to P = 1.5 kW and the heating is resumed. If YES in step S515, boiling detection is performed, and after a predetermined time, the output is reduced to a predetermined value, for example, 200 W, and kept warm.

  Thereafter, the process proceeds to step S521, and the detection value Ttod of the infrared sensor 32 at the time of boiling determination is regarded as a value corresponding to 100 ° C. and stored as Tb. Further, the control temperature Tsk after boiling is obtained by Tsk = k · Tb with respect to the detection value Tb corresponding to 100 ° C. However, k = target set temperature / 100. Then, Ttod is controlled to reach this control temperature Tsk (steps S523 to S531). This temperature control is continued until the end of heating is input (steps S533 and S535).

  In the boiling water control example 6, when the boiling is detected, the heating output is reduced and the change in the output of the infrared sensor is detected to estimate the temperature of the liquid temperature. Therefore, accurate boiling detection is possible even for a high viscosity liquid. It becomes possible.

[Water heater control example 7]
With reference to the graph of FIG. 33 and the flowchart of FIG. In the control example 7, after detecting that the time during which Δ ² Ttod / Δt ² in the control example 5 is equal to or less than the second predetermined value Ts4 has continued for a predetermined time Ht (step S411 in the flowchart of FIG. 32), the thermal power P Is reduced from 1.5 kW to 0.5 kW (= Pl), and the elapsed time δt (i) (i = 1, 2, 3,...) From time tf (i) to to (i + 1) is counted. . Next, it is determined whether Ttod decreases and the absolute value of δTt / Ttod is larger than a predetermined value kts, and the elapsed time δt when | δTt / Ttod | ≧ kts is longer than the predetermined time δts. It is characterized by detecting boiling in the case. The predetermined values Ts3 and Ts4 are the same as those in FIG.

  Next, a boiling water control example 7 will be described with reference to the flowchart of FIG. In Control Example 7, induction heating is started at the start of heating in step S551. In step S553, it is determined whether or not the detection value Ttod of the infrared sensor 32 exceeds a predetermined value Ts1 set in advance. If it does not exceed, it will transfer to NO and will continue heating. And if it exceeds, it will transfer to YES and it will be determined whether the detection value Ttod of the infrared sensor 32 has exceeded the upper limit of a temperature rise control data series (step S555). If it exceeds, the temperature rise control data series is switched and induction heating is continued.

If the detection value Ttod of the infrared sensor 32 does not exceed the upper limit value of the temperature rise control data series in step S555, the process branches to YES, and the change in the change rate of Ttod ΔTtod / Δt, that is, Δ ² Ttod / Δt ² is 0 or It is determined whether or not it has become a positive value after it has become a negative value (step S557). If it becomes a positive value after a negative value, it branches to YES and continues induction heating. On the other hand, if the negative value continues or the positive value continues, the process branches to NO and proceeds to step S559.

In step S559, it is determined whether or not the change rate change Δ ² Ttod / Δt ² is equal to or less than a predetermined value Ts3. If the temperature rises to near the boiling temperature, the rate of temperature rise becomes dull, and the detected value change rate ΔTtod / Δt decreases, so that the change rate change becomes a negative value. Also here, if larger than the first predetermined value Ts3, the process branches to NO and the induction heating is continued. On the other hand, if the change in change rate is equal to or less than the negative first predetermined value Ts3, the process branches to YES and proceeds to step S561 for boiling detection determination.

  If the temperature rise of the water temperature tw is smooth, the rate of change in temperature does not fluctuate greatly before and after the time when the rate of change in temperature becomes dull and the value of change in rate of change becomes negative. Therefore, if the change rate change is equal to or less than the negative first predetermined value Ts3, it is determined in step S561 whether or not the duration during which the change rate change is equal to or less than the second predetermined value Ts4 is the predetermined time Ht. . In the case of NO at step S561, induction heating is continued.

  If YES in step S561, the thermal power P is set to 0.5 kW (Pl), and the elapsed time δt after tf (i) (i = 1, 2, 3,...) Is counted (step S563). Whether or not the absolute value obtained by dividing the change δTt (i) of the detection value Ttod by the infrared sensor during δt by the detection value Tt (i) by the infrared sensor before dropping the thermal power is larger than the predetermined value kts of the change. Determine. That is, it is determined whether or not | δTt (i) / Tt (i) | ≧ kts (step S565). Tt (i) is the same as Ttod.

  In the case of NO in step S565, induction heating is continued. If YES in step S565, it is determined whether the elapsed time δt is longer than the predetermined time δts (step S567), and if it is longer, boiling is detected.

  If boiling is detected in step S567, the process proceeds to step S569, and the detection value Ttod of the infrared sensor 32 at the time of boiling determination is regarded as a value corresponding to 100 ° C. and stored as Tb. Further, the control temperature Tsk after boiling is obtained by Tsk = k · Tb with respect to the detection value Tb corresponding to 100 ° C. (step S571). However, k = target set temperature / 100. Then, Ttod is controlled to reach this control temperature Tsk (steps S573 to S577). This temperature control is continued until the end of heating is input (steps S579 and S581). The control in steps S569 to S581 is the same as that in steps S209 to S221 of the control example 1 shown in FIG.

  In the boiling water control example 7, in addition to the effect of the control example 5, similarly to the control example 6, it is possible to detect boiling with high accuracy even for a liquid having a high viscosity.

[Second Embodiment]
8 to 11 show a second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different parts will be described below. FIG. 9 shows an example of a preheating control data series (excluding the data series (10)) stored and held in the internal memory as a data table. 9 represents the scale of the output voltage Vto [mV] of the infrared sensor 32 together with the lower surface temperature Tpu of the top plate 16, and the vertical axis represents the heating power P [kW] of induction heating. Data series (1) to (9) show a series of preheating control data [temperature rise control data] using the lower surface temperature Tpu, which rises in increments of 25 ° C. from 25 ° C., as a parameter.

  In this case, the thermal power decay rate (straight line) of the data series (1) to (9) depends on the infrared energy radiated when the temperature of the bottom of the shiny SUS pan reaches 250 ° C., for example. Thus, the voltage Vb is set to correspond to 20 mV output from the infrared sensor 32. The data series (1) to (9) discretely indicate rough values for the lower surface temperature Tpu, but the data actually used is obtained by dividing the lower surface temperature Tpu in more detail.

  For example, in the data series (1), when the lower surface temperature Tpu = 25 ° C., when the output voltage Vto = 10 mV is reached, the thermal power P is reduced from the initial value 3 kW, and when the output voltage Vto = 30 mV is reached, the thermal power P is the lowest output. This is set to 200W. Further, in the data series (6), when the lower surface temperature Tpu = 150 ° C., the thermal power P is reduced from the initial value 3 kW when the output voltage Vto = 140 mV, and when the output voltage Vto reaches 160 mV, the thermal power P is minimum output. Set to 200W. If the lower surface temperature Tpu changes during preheating, the data series to be used is dynamically changed accordingly.

  For the data series (not shown) located on the right side of the data series (9), the lower surface temperature Tpu is set to a vertical inclination at a temperature corresponding to the case where the temperature of the bottom of the SUS pan is 250 ° C. If it is set, the data series is set as the upper limit. This upper limit can be arbitrarily set. For example, if the slope of the data series (6) corresponding to the lower surface temperature Tpu = 150 ° C. is set to “0”, the data series (6) becomes the upper limit. About these data series (1)-(9), when following a normal cooking procedure, in order to preheat cooking utensils 35, such as a frying pan, it is used in the period which raises temperature. The data series (1) to (9) are data series for proportionally controlling the thermal power P according to the detection output of the infrared sensor 32.

  The data series (10) [temperature control data series] is thermal power data used when cooking is performed according to the temperature Tpu detected by the temperature sensor 39, and the thermal power P is proportionally controlled according to the detection output. It is a data series for doing this. And FIG. 9 has shown the variation in the case of changing a data series (10) according to the cooking setting by a user. That is, the data series (10) shown in FIG. 9 is an example, and actually one of the data series shown in FIG. 10 is selected according to the setting of the cooking menu by the user. The data series (10) in FIG. 9 corresponds to the data series (11a) in FIG.

  These are divided into approximately four groups, and the first group of the data series (1-3) is, for example, cooking such as “Toro Toru Omelette” or “Hot Cake” with a heating temperature of about 140 ° C. to 160 ° C. Corresponding to The second group of the data series (4 to 6) corresponds to cooking such as “hamburg” where the heating temperature is about 170 ° C. to 190 ° C., for example, and the third group of the data series (7 to 14) is, for example, heated It corresponds to cooking such as “steak” whose temperature is about 200 ° C. to 220 ° C. And the 4th group of a data series (12a-14a) respond | corresponds to cooking, such as "stir-fried vegetables" in which heating temperature becomes about 220 to 270 degreeC, for example. Moreover, in the case of "fried food" cooking, since heating temperature will be about 140 to 200 degreeC, it will straddle both the 1st group and the 2nd group.

  In other words, when cooking is performed after the preheating is completed and the temperature of the cooking utensil 35 is stabilized, the data series (10) is mainly used, but additional ingredients are added during the cooking. If the temperature of the cooking utensil 35 is temporarily reduced, the control may return to the control using the data series (1) to (9). These data series (1) to (10) are not limited to those stored and stored in advance as data tables, and may be calculated using arithmetic expressions (functions).

  Also in the second embodiment, similarly to the first embodiment, the appropriate temperature notification control function shown in FIGS. 17 and 18 is provided and applied at the time of reheating when the temperature of the frying pan is lowered.

  FIG. 8 is a flowchart showing induction heating control performed by the thermal power control device 41. First, the lower surface temperature Tpu of the top plate 16 is detected based on the output voltage of the temperature sensor 39 (step S11), and then the output voltage Vto (lower horizontal axis in FIG. 9) of the infrared sensor 32 is detected (step S12). ). Then, the preheating thermal power PS1 is set based on the data series shown in FIG. 9 according to the temperature Tpu and the output voltage Vto (step S13). That is, one of the data series (1) to (9) is selected according to the temperature Tpu, and the heating thermal power PS1 is set according to the output voltage Vto on the selected data series.

  Subsequently, based on the temperature Tpu, based on the data series (10) shown in FIG. 9, the heating power PS2 for performing cooking is set (step S14). Then, the power value corresponding to the thermal power P that is actually output is detected (step S15). Subsequent steps S16 to S18 are common controls during preheating and heating. That is, the thermal power P detected in step S15 is compared with the preheating thermal power PS1 or the heating thermal power PS2 (step S16). If [P <PS1: PS2], the thermal power P is increased (step S17). If P> PS1: PS2], the thermal power P is decreased (step S18). If [P = PS1: PS2], the process directly returns to step S1. As described above, the preheating control and the subsequent heating control can be performed in accordance with the control data series shown in FIG. 9 (as described above, the heating control may be shifted to the preheating control).

  The operation described above will be described with reference to load lines Ls2 and Ls4 shown in FIG. These load lines Ls2 and Ls4 have an upward slope because the amount of heat released from the cooking utensil 35 increases as the temperature of the cooking utensil 35 rises. “Heat dissipation” in this case is mainly caused by the bottom of the cooking utensil 35 being deprived of heat, for example, by vegetables, heating of the cooking utensil 35 itself (temperature rise), heat dissipation from the cooking utensil 35, or the like. It is caused by heat being taken away from. Therefore, the actual load line changes in a quadratic curve, but is shown as a straight line in FIG.

  For example, assuming that “stir-fried vegetables” is cooked, the inclination of the load line is steep when the vegetable contains a lot of moisture in the initial stage of cooking, but it is included in the vegetable as cooking progresses. Moisture is reduced and heat is hardly taken from the bottom of the cooking utensil 35. Then, the load line becomes Ls2, and when cooking further proceeds, the load line changes as Ls4. The thermal power P is determined by the intersection of the load line and the data series (1) to (10).

  In the state where the load line is Ls2, before reaching Ps2, which is the intersection with the data series (10), if the lower surface temperature Tpu = 125 ° C., the data series (5) intersects with Ps2 ′. As the output voltage Vto increases, the thermal power P is decreased.

  On the other hand, even when the lower surface temperature Tpu = 150 ° C. when the load line is Ls2, the data series (6) is not transferred. This is because the thermal power set value PA, which is the intersection of the extension line of the load line Ls2 and the data series (6), exceeds the data series (10) that is the upper limit value, and therefore the thermal power set value is the data series (10 This is because it is transferred to the proportional control data according to). That is, on the horizontal axis (upper side) in FIG. 9, the thermal power set value PB of the data series (10) corresponding to the temperature Tpu = 150 ° C. is the operating point.

  When the load line reaches Ls2 and reaches Ps2, which is the intersection with the data series (10), since the data series (10) is the upper limit value, the thermal power control is shifted to the data series (10). The proportional control according to the data series (10) is executed based on the lower surface temperature Tpu on the horizontal axis (upper side) of 9.

  When the load line shifts to Ls4 and rises to the lower surface temperature Tpu = 150 ° C., it intersects with the data series (6) at Ps4. If cooking further proceeds from this state, the slope of the load line becomes smaller than Ls4. On the other hand, when vegetables are newly added to the cooking utensil 35, the slope of the load line changes so as to stand.

  As described above, when the slope of the load line changes according to the progress of cooking, when the load line intersects the data series (10) due to the relationship with the lower surface temperature Tpu, the heating control is performed by the temperature sensor 39. This is performed based on the data series (10) according to only the lower surface temperature Tpu which is the detection output. That is, in FIG. 9, the data series that is the upper right area with the data series (10) as a boundary is not used for the thermal power control, and all the controls are the lower left area with the data series (10) as a boundary. It is based on the data over.

  FIG. 11 shows a list of how to handle detection outputs obtained from the two temperature sensors 39a and 39b when the lower surface temperature Tpu is acquired in step S1. That is, these processes are changed according to the type of cooking menu selected by the user and the progress of cooking.

  For example, when the cooking menu is “frying pan cooking”, the one in which the detected temperature is lower is adopted among the detection outputs of the temperature sensors 39a and 39b during the preheating period. Then, after preheating, if the submenu is “steak”, for example, the lower detection temperature is used, and if the submenu is “cutlet”, the higher detection temperature is used. If the cooking menu is “stir-fried vegetables”, the one with a consistently high detection temperature is adopted, and if “cooked with egg”, the one with a consistently low detection temperature is adopted.

  That is, in the case of “frying pan cooking: steak”, since the amount of oil drawn to the frying pan is generally small and the temperature of the frying pan is likely to rise, the data series (1) to (9) are selected and set according to the lower detection temperature during preheating. To do. And when preheating is completed and cooking is performed, conversely, control data based on the data series (10) is set in accordance with the higher detected temperature. In the case of “frying pan cooking: cutlet”, the amount of oil drawn to the frying pan is generally large and the temperature of the frying pan is unlikely to rise. Therefore, both in the case of cooking at the time of preheating and after preheating, the data series (1) to (9) are selected and set according to the lower detected temperature, and control data based on the data series (10) is set.

  In the case of “stir-fried vegetables”, since cooking is performed at a high temperature, the data series (1) to (10) are selected and set according to the one with the higher detected temperature in both cases of preheating and cooking after preheating. To do. In the case of “tamagoyaki”, it is desirable that cooking is performed at a relatively low temperature and the entire bottom surface of the cooking utensil 35 is heated uniformly. Therefore, an average value of the detection outputs of the two temperature sensors 39a and 39b is used. adopt.

  As described above, according to the second embodiment, the thermal power control device 41 uses the thermal power generated by the heating unit 48 according to the detection output of the temperature sensor 39 during the period when the temperature of the cooking utensil 35 rises as in preheating. In addition to setting the data series (1) to (9) for controlling the detection, the detection output of the infrared sensor 32 (the detection output of the infrared sensor 32 corresponding to the radiant energy from the lower surface of the top plate 16 is reduced and not eliminated) The thermal power setting value according to the set data series is determined from the data series (1) to (9) according to the infrared output). Therefore, the data series (1) to (5) set according to the detection output without reducing the detection output of the infrared sensor 32 and eliminating the information contained in the detection output as described in Patent Document 1 without using the information included in the detection output. Since the set value of (9) is changed, even when the heat capacity of the cooking utensil 35 is small, the temperature rise degree can be controlled with high accuracy, and it is possible to reliably prevent an excessively high temperature state.

  Further, since the thermal power control device 41 also sets a data series (10) for controlling the thermal power by the heating means 48 according to the detection output of the temperature sensor 39, preheating is finished, the upper surface of the top plate 16, When cooking with the temperature of the lower surface being relatively stable, the control accuracy and cooking performance can be improved by performing proportional control according to the detection output of the temperature sensor 39.

  The thermal power control device 41 sets the upper limit value of the former thermal power output P to be equal to or higher than the upper limit value of the latter when the upper limit value is set for each of the data series (1) to (9) and the data series (10). Therefore, even when the cooking utensil 35 is made of, for example, glossy SUS, the overheat prevention function can be realized with high accuracy.

  Since the data series (1) to (9) and the data series (10) are set as data for proportionally controlling the thermal power P according to the detection output of the infrared sensor 32 and the detection output of the temperature sensor 39, respectively. For example, even when it is assumed that the temperature of the cooking utensil 35 suddenly rises during preheating of frying pan cooking, the excessive temperature rise prevention function can be realized with high accuracy. In addition, when cooking is performed in a state where the temperature of the upper and lower surfaces of the top plate 16 is relatively stable after preheating is finished, the control accuracy and cooking performance are improved by proportional control according to the detection output of the temperature sensor 39. Can do.

  Further, the thermal power control device 41 prepares a plurality of data series (10) corresponding to the cooking conditions, and selects any one according to the cooking conditions set via the operation units 20AT to 27AT. When cooking, fried food cooking, or the like is selected, it is possible to set a data series for performing optimal proportional control according to each cooking mode.

  In addition, the thermal power control device 41 adopts an average value of the detection results output from the temperature sensors 39a and 39b or selects one of the detection results according to the data series (1) to ( 9) is set, and the control data according to the data series (10) is determined based on one of the detection result indicating the lowest temperature, the detection value indicating the highest temperature, or the average value of the detection results. .

  That is, in the induction heating, as shown in FIG. 15, since the distribution of the induced current flowing in the bottom of the cooking appliance 35 is uneven, the temperature distribution of the pot bottom is also uneven. Moreover, when the shape of the pan bottom is uneven, the detection result of the temperature sensor 39 may vary. Therefore, if the detection result output from the temperature sensors 39a and 39b has the highest temperature, it can be controlled safely from the viewpoint of preventing excessive temperature rise. Further, if the detection result having the highest temperature is employed, the change rate of the control data based on the data series can be increased. For example, when cooking with high heating power such as “stir-fried vegetables”, a higher heating power can be set. In addition, if an average value is adopted for the detection result, it is suitable for control that requires accuracy in the heating temperature, such as “eggaki”.

  Even in this embodiment, the proper temperature notification function shown in FIG. 17 and FIG. 18 makes the oil temperature rapidly rise even in the case of fried food cooking with a small amount of oil such as preheated with a frying pan or cutlet. It is possible to suppress the excessive temperature rise. At the same time, even when using a pan at the bottom of the pan or a pan with a different infrared radiation rate, it is possible to accurately notify the proper temperature at which tempura cooking can be started and to notify the completion of preheating of frying pan cooking.

  In addition, in the appropriate temperature notification control, by changing the setting value of the temperature rise control table according to the detection output of the infrared sensor 32, preheating with oil in a frying pan or cooking of fried food with a small amount of oil such as cutlet However, it is possible to prevent overshoot due to a sudden rise in the oil temperature, and at the same time, it is possible to quickly recover the thermal power against the temperature drop at the time of frying pan cooking or tempura cooking utensils input, and the cooking performance can be improved.

  Also in the present embodiment, it is possible to employ a control for heating and heating while sequentially shifting the infrared temperature upper limit value to the high temperature side in accordance with the temperature rise of Tpu during the heating and heating shown in FIG. Moreover, the control which correct | amends an infrared temperature target value by the difference of the sled of a pan shown in FIG. 19, FIG. 21 or a material is employable.

  Further, in the present embodiment, as in the first embodiment, the control unit 41 sets the upper limit value (7) in the temperature rise control data series (1) to (7), and the temperature sensor 39. The heating power setting according to the upper limit value of the temperature rise control data series (7) of the infrared sensor 32, regardless of the detection output of the temperature sensor 39, when the temperature exceeds a predetermined value lower than the temperature corresponding to the upper limit value by a certain value. The value can be used to control the thermal power.

  Also in the induction heating cooker of the second embodiment, any of the boiling control function and the boiling water control examples 1 to 7 similar to those of the first embodiment can be incorporated in the thermal power control device 41, thereby As with the first embodiment, accurate boiling control can be performed.

[Other embodiments]
The present invention is not limited to the embodiments described above or shown in the drawings, and the following modifications or expansions are possible. For example, the handling of the detection outputs of the plurality of temperature sensors is not limited to that shown in FIG. 11, and may be changed as appropriate according to the individual design. Only one temperature sensor or three or more temperature sensors may be provided. Only one induction heating coil or three or more induction heating coils may be provided. About a data series (10), providing a variation for every cooking menu should just be performed as needed. Each data series is not necessarily limited to data for which proportional control is performed, and may be changed as appropriate. Furthermore, the cooking utensil 35 is not limited to a frying pan, and can be similarly applied to other pans.

2 Heating cooker (Induction heating cooker)
8, 9 Induction heating coils 12H, 15H Cooking condition display unit 16 Top plate 20AT-27AT Operation unit 32 Infrared sensor 35 Cooking utensil (object to be heated)
39 Temperature Sensor 41 Thermal Power Control Device (Control Unit)
42 Inverter 48 Heating means

Claims (4)

A top plate on which an object to be heated is placed;
A heating means installed below the top plate and inductively heating the object to be heated by a heating coil;
An infrared sensor for detecting infrared radiation radiated from the top plate and the object to be heated;
A control unit for controlling the heating power of the heating means by a temperature rise control data sequence determined by a detection value of the infrared sensor,
The control unit compares the spectral radiation detection characteristic of the infrared sensor with the radiation energy of a pot having a pan bottom with an emissivity of approximately 100% in the infrared region, and detects the radiation energy of the glass more. Detecting by boiling detection and detecting boiling, and at the time when boiling is detected, the thermal power is reduced, and the continuation or stop of the boiling detection is determined by the detection value change of the infrared sensor after the thermal power is reduced. Induction heating cooker.   2. The induction heating cooker according to claim 1, wherein the change in the detection value of the infrared sensor after the thermal power is reduced determines whether the boiling detection is continued or stopped based on a ratio to the infrared sensor detection temperature.   The induction heating cooker according to claim 1, wherein a change in the detected value of the infrared sensor after the thermal power is reduced is detected by a change in the detected value when the thermal power is reduced for a predetermined time.   The induction heating cooker according to claim 1, wherein the rate of change in the detection value of the infrared sensor after the thermal power is reduced is determined by a time until a predetermined change in the detection value occurs when the thermal power is reduced.

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