JP2004227816A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to improve cooking performance even in a situation that sufficiently precise temperature detection of a heated material is not obtained. <P>SOLUTION: A thermistor 4 detects the temperature of the heated material on the top plate. An electric power detecting part 27 integrates an input electric power of an induction heating means including a heater coil 2. A memory part 34 for heated part criteria stores the correlation of the integrated value of the input electric power by the electric power detecting part 27 and the detected temperature by the thermistor 4 as criteria value information to obtain information (such as cooking type, warping of the bottom of a pot, and the like) of the heated material. A heated article detecting part 29 obtains information on the heated material based on the result of the comparison of the criteria value information, the input electric power integration value, and the detected temperature by the thermister 4, and outputs the result. Heating output control means 36 receives output from the heated article detection part 29 and the setting output by an operation/display part 35 as an output control information, and governs the action of controlling the heating output by the induction heating means based on the output control information. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an induction heating cooker for induction heating an object to be heated using a heating coil and an inverter circuit.
[0002]
[Prior art]
In an induction heating cooker, the heating output is feedback-controlled based on the temperature of the object to be heated.In this case, a temperature sensor such as a thermistor is used to detect the temperature of the object to be heated. Used. However, the induction heating cooker is generally provided with a so-called smooth stop specification in consideration of improvement in cleanability and design, so that the temperature sensor is provided on the lower surface of the top plate. And the temperature of the object to be heated placed on the top plate is detected via the top plate. However, the top plate is generally made of a heat-resistant tempered glass having a thickness of about 4 mm and has poor thermal conductivity, so that it is difficult to accurately detect the temperature of the object to be heated. Adversely affected the situation.
[0003]
In order to cope with such a situation, conventionally, in an induction heating cooker in which a temperature sensor is arranged on the lower surface of a top plate, a boiling state of water in a pot placed on the top plate is detected by the temperature sensor. It is considered that the determination is made based on the measured temperature gradient and the elapsed time after the start of the heating operation (for example, see Patent Document 1). Conventionally, in an induction heating cooker in which a temperature sensor is arranged on the lower surface of a top plate, when performing oil temperature control based on the detection temperature of the temperature sensor when performing fried food cooking such as tempura, the detection is not performed. It has been considered to adopt a configuration in which a setting performance is controlled based on a temperature gradient to obtain cooking performance suitable for fried food cooking (for example, see Patent Document 2).
[0004]
[Patent Document 1]
Japanese Patent Publication No. 6-75425
[0005]
[Patent Document 2]
Japanese Patent Publication No. 6-65144
[0006]
[Problems to be solved by the invention]
In the conventional configuration, since the actual temperature of the object to be heated is estimated based on only the temperature detection information and the time information from the temperature sensor, the amount of the food and the contact state between the pan and the top plate ( For example, there is a problem that an error in the detected temperature is inevitably increased due to the influence of, for example, the degree of warping of the bottom of the pot, and as a result, it is difficult to sufficiently improve the cooking performance. Also, for example, when a user mistakenly starts cooking in a normal heating mode (a mode in which cooking is performed with a constant heating output) when cooking fried food such as a tempura, the temperature of the oil in the pan is dark. Could have risen.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to greatly improve the cooking performance even in a situation where the accuracy of detecting the temperature of an object to be heated is not sufficiently obtained. An object of the present invention is to provide an induction heating cooker that plays.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 provides a top plate on which a cooking vessel is placed, a heating coil for induction heating the cooking vessel, and an inverter circuit for supplying a high-frequency current to the heating coil. Induction heating means, operating means for setting cooking conditions such as heating output by the induction heating means, power integration means for integrating input power or input current of the induction heating means, and temperature of the object to be heated. And the correlation between the integrated value of the power integrating means and the temperature detected by the temperature detecting means are stored as determination reference value information for obtaining information about the object to be heated. Information storage means, determination reference value information stored in the information storage means, an integrated value by the power integration means, and a temperature detected by the temperature detection means. And an object to be heated detecting means for acquiring and outputting information about the object to be heated based on the result of comparison with the object to be heated, and receiving the output from the object to be heated detecting means and the setting output by the operating means as output control information. And a heating output control means for performing an operation of controlling the heating output by the induction heating means based on the output control information.
[0009]
According to this configuration, at the time of the cooking operation using the cooking vessel, that is, at the time of induction heating of the object to be heated (the cooking vessel and the food stored therein) by the induction heating means, the input power or the input current of the induction heating means. Are integrated by the power integrating means, and the temperature of the object to be heated is detected by the temperature detecting means. The integrated value by the power integrating means corresponds to the energy actually consumed for heating the object to be heated, and the temperature detected by the temperature detecting means is determined by the type of cooking operation (specifically, For example, cooking pots where the heating target is water, fry cooking where the heating target is oil, etc., the type and weight of the cooking container such as a pan, the degree of warping of the bottom of the cooking container (between the cooking container and the temperature detecting means) Temperature transmission state), the amount of food, and the like. Therefore, the correlation between the integrated value by such power integrating means and the temperature detected by the temperature detecting means is based on the type of cooking operation, the type and weight of a cooking vessel such as a pan, the degree of warping of the bottom of the cooking vessel, The correlation differs depending on the amount and the like, and such a correlation is stored in the information storage means as determination reference value information.
[0010]
Then, in the heated object detection means, information on the heated object is obtained based on a result of comparing the determination reference value information stored in the information storage means with the integrated value by the power integration means and the temperature detected by the temperature detection means. (The type of cooking operation, the type and weight of a cooking container such as a pan, the degree of warpage of the bottom of the cooking container, the amount of food, etc.) are obtained and output. In addition, the heating output control means receives the output from the object-to-be-heated detecting means (information about the object to be heated) and the setting output by the operating means (cooking conditions such as heating output) as output control information. An operation of controlling the heating output by the induction heating means based on the control information is performed.
[0011]
Therefore, since the temperature of the object to be heated is detected via the top plate, the error of the detected temperature increases, but the integrated value of the power integrating means, that is, the actual value for heating the object to be heated. The heating output can be optimally controlled based on the interrelationship between the consumed energy and the detected temperature, thereby improving the cooking performance.
[0012]
In this case, as in the invention described in claim 2, the heating output control means stores a plurality of types of heating output control patterns corresponding to the temperature detected by the temperature detecting means or the cooking time, and Any one of the plurality of types of heating output control patterns can be selected according to the output from the detecting means, and the heating output by the induction heating means can be controlled based on the selected heating output control pattern. .
According to this configuration, information on the object to be heated outputted from the object to be heated detection means (the type of cooking operation, the type and weight of a cooking container such as a pan, among the plurality of types of heating output control patterns set in advance). The control pattern is selected according to the degree of warpage of the bottom of the cooking container, the amount of the food, and the like, and the heating output by the induction heating means is controlled based on the heating output control pattern. Therefore, by appropriately setting a plurality of types of heating output control patterns in advance, the heating output can be optimally controlled.
[0013]
According to a third aspect of the present invention, the object to be heated is stored in the cooking container based on a curvature of a characteristic curve indicating a relationship between an integrated value of the power integrating unit and a temperature detected by the temperature detecting unit. A configuration for determining the type of object may be used.
In general, when water is stored in a cooking container, that is, when cooking a hot pot in which the object to be heated is water, the integrated value by the power integrating means indicating the energy actually consumed for the heating, and the temperature. The characteristic curve indicating the relationship with the temperature detected by the detecting means has a linear shape. In addition, when the stored item in the cooking container is other than water, the characteristic curve varies depending on the type of the stored item. Therefore, the object-to-be-heated detecting means can accurately judge the type of the storage item in the cooking container based on the curvature of the characteristic curve.
[0014]
According to a fourth aspect of the present invention, the object-to-be-heated detecting means is provided with a change amount of an integrated value by the power integrating means corresponding to a change amount per unit time of a temperature detected by the temperature detecting means, or A configuration may also be adopted in which information on the object to be heated is obtained based on a relationship between the amount of change in the integrated value per unit time by the integrating means and the amount of change in the detected temperature by the temperature detecting means.
[0015]
According to a fifth aspect of the present invention, the object-to-be-heated detecting means obtains information about the object-to-be-heated based on the integrated value of the power integrating means each time the temperature detected by the temperature detecting means changes by a predetermined amount. Alternatively, a configuration may be adopted in which the information about the object to be heated is acquired based on the temperature detected by the temperature detecting means each time the integrated value of the power integrating means changes by a predetermined amount.
According to this configuration, the operation of acquiring information about the object to be heated is performed every time the temperature detected by the temperature detecting unit changes by a predetermined amount, or every time the integrated value of the power integrating unit changes by a predetermined amount, that is, for a predetermined time. Since the repetition is performed each time, it is useful for performing optimal control of the heating output.
[0016]
As in the invention according to claim 6, a control mode for water heating is set in the heating output control means, and the object to be heated detection means is set to the temperature detection means when the control mode for water heating is selected. Based on the detected temperature and the integrated value of the power integrating means, a heating output amount required to raise the temperature of the object to be heated to a predetermined target heating temperature is predicted, and the prediction result is transmitted to the heating output control means. Alternatively, a configuration in which the information is provided as output control information may be employed.
According to this configuration, in a state where the heating output by the induction heating means is controlled in the control mode for boiling water, the object to be heated (water stored in a cooking container such as a kettle at the time of such boiling) is targeted. The amount of heating output required to raise the temperature to the heating temperature is predicted, and the heating output control means controls the heating output by the induction heating means based on the prediction result. For this reason, immediately before boiling of water, the heating output is automatically suppressed, and a heating operation with an excessive heating output is performed immediately before the boiling of water, and boiling water is spilled. It is possible to prevent inviting situations.
[0017]
When the heating control for the water heater is performed, the control mode for the water heater is controlled by the heating by the induction heating means in accordance with an increase in the temperature detected by the temperature detecting means. The output can be tapered.
According to this configuration, the heating output is gradually reduced as the water being heated approaches the boiling state, which is beneficial in reliably preventing boiling water from spilling over.
[0018]
As in the invention according to claim 8, a function of displaying the set heating output and a function of displaying the actual heating output when the actual heating output is changed by the heating output control means are provided for the operating means. It is good also as composition.
According to this configuration, the heating output set by the operation unit is displayed, and when the actual heating output is changed by the heating output control unit during the subsequent cooking operation, the changed heating output is displayed. Therefore, on the user side, the operation of correcting the heating output according to the actual progress of the cooking operation can be performed at its own discretion. That is, for example, in the case where control for reducing the heating output is performed by the heating output control means during fried food cooking, when the user determines that such output reduction control is unnecessary, an operation of increasing the heating output can be performed. Thus, it is useful when actually cooking.
[0019]
According to a ninth aspect of the present invention, the operating means is provided with an operating section for selecting a stir-fry cooking course, and the heating output control means is operated when the stir-fry cooking course is selected. The configuration is such that the temperature of the heated object is controlled to be higher than during normal heating.
According to this configuration, stir-fry cooking requiring high-temperature heating can be effectively performed.
[0020]
In this case, in addition to the stir-fry cooking course selection function, a heating output setting function and a fried food cooking course selection function are set in the operating means, and then the heating output control means is set. In the state where the stir-fry cooking course is selected, the temperature of the object to be heated is controlled to be higher than the state where the heating output is set by the heating output setting function and the state where the fried food cooking course is selected. It can also be configured.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an induction heating cooker (IH cooking heater) will be described with reference to the drawings.
FIG. 2 schematically shows a cross-sectional structure of a main part. In FIG. 2, the top plate 1 is made of heat-resistant tempered glass having a thickness of about 4 mm, and a well-known heating coil 2 is installed below the top plate. A metal cooking container 3 is placed on the top plate 1 at a position corresponding to the heating coil 2. On the lower surface of the top plate 1, a thermistor 4 (corresponding to a temperature detecting means) for detecting the temperature of the object to be heated (the cooking container 3 and the food stored therein) by the heating coil 2 is thermally conductive. It is a structure attached to.
[0022]
FIG. 1 shows the overall electrical configuration. 1, a DC power supply circuit 5 includes a rectifying stack 7 for full-wave rectifying the output of an AC power supply 6 and a smoothing capacitor 8 for smoothing the rectified output. The half-bridge type inverter circuit 9 supplied with power from the DC power supply circuit 5 constitutes the induction heating means according to the present invention together with the heating coil 2. The inverter circuit 9 connects the series circuit of the IGBTs 10 and 11 and the series circuit of the capacitors 12 and 13 for resonance in parallel with the smoothing capacitor 8, respectively, and also connects the common connection point of the IGBTs 10 and 11 and the common connection of the capacitors 12 and 13. The heating coil 2 is connected so as to form a series resonance circuit between each of the capacitors 12 and 13 and a connection point. In addition, flywheel diodes (no symbol) are connected between the collectors and the emitters of the IGBTs 10 and 11, respectively.
[0023]
The inverter voltage phase detection circuit 14 detects the inverter voltage Viv output from the output terminal of the inverter circuit 9 (the common connection point of the IGBTs 10 and 11), and outputs the detected inverter voltage Viv to the phase comparison circuit 15. The capacitor voltage phase detection circuit 16 detects a voltage at a common connection point of the capacitors 12 and 13, that is, a capacitor voltage Vc which is phase-correlated with the inverter current flowing through the capacitors 12 and 13, and detects the detected voltage Vc. Output to the phase comparison circuit 15.
[0024]
The phase comparison circuit 15 outputs a phase difference signal Vp1 indicating the phase difference between the input signals by comparing the phases of the inverter voltage Viv and the capacitor voltage Vc, and outputs the phase difference signal Vp1 to the difference comparison circuit 17. Given. The phase difference setting circuit 18 is configured to output a variably settable phase difference setting voltage Vset as an input power adjustment signal for determining input power, and the phase difference setting voltage Vset is supplied to the difference comparing circuit 17. Given.
[0025]
The difference comparison circuit 17 compares the magnitude of the phase difference signal Vp1 output from the phase comparison circuit 15 with the phase difference setting voltage Vset variably set in the phase difference setting circuit 18, and compares the comparison result with a binary signal. The signal is output to a voltage controlled oscillator (hereinafter, referred to as a VCO) 19 as Vp2. That is, the difference comparison circuit 17 increases Vp2 if Vp1> Vset, and decreases Vp2 if Vp1 ≦ Vset.
[0026]
The VCO 19 is frequency control means for controlling the oscillation frequency of the inverter circuit 9 so that the phase difference between the inverter voltage Viv and the capacitor voltage Vc is variably set by the phase difference setting circuit 18. The oscillation frequency is changed according to the output signal from the circuit 17.
[0027]
Incidentally, a VCO as a general analog circuit changes its oscillation frequency in accordance with an input voltage, but the VCO 19 here simulates the circuit operation digitally, and a difference comparison circuit 17. The configuration is such that the oscillation frequency is changed in accordance with the comparison result given by the user.
[0028]
The drive circuit 20 turns on and off the IGBTs 10 and 11 alternately based on a signal from the VCO 19. When the IGBTs 10 and 11 are turned on and off alternately in this manner, the heating coil 2 and one of the capacitors 12 and 13 alternately exhibit a series resonance state. The induction heating of the cooking container 3 mounted on 1 is carried out.
[0029]
The initial circuit 21 is means for initially setting the phase difference between the inverter voltage Viv that is phase-correlated with the output voltage of the inverter circuit 9 and the capacitor voltage Vc that is phase-correlated with the output current of the inverter circuit 9. When the power is turned on, an initial signal is given to the phase difference setting circuit 18. In this case, the phase difference setting circuit 18 outputs the phase difference setting voltage Vset such that the phase difference between the inverter voltage Viv and the capacitor voltage Vc becomes a reference phase difference when the initial signal is given. Has become. Thereby, the input power is set to a predetermined initial set power (for example, about 100 W when the cooking container 3 placed on the top plate 1 is an iron pot). The operation with the initial set power is performed only for a very short time at the beginning of cooking.
[0030]
The current transformer CT (1) is provided in a state where a current path between the AC power supply 6 and the DC power supply circuit 5 is a primary conductor in order to detect an input current Iin from the AC power supply 6. The input current detection circuit 22 outputs a current detection signal of a voltage level corresponding to the input current Iin based on the secondary output of the current transformer CT (1), and outputs the current detection signal to the load state detection circuit. 23, and to an electric energy detector 27 via an A / D converter 26b.
[0031]
The load state detection circuit 23 detects whether or not the object to be heated (cooking container 3) placed on the top plate 1 has an appropriate load based on the current detection signal from the input current detection circuit 22.
Here, the detection operation in the load state detection circuit 23 will be described with reference to FIG. FIG. 3 is a characteristic diagram showing the input current Iin with respect to the phase difference setting voltage Vset output from the phase difference setting circuit 18 for each load state, for example, for each material of the object to be heated. More specifically, curve a in the drawing is a characteristic curve in a no-load state, curve b in the drawing is a characteristic curve for an aluminum cooking container, and curve c in the drawing is a non-magnetic stainless steel cooking container. Is a characteristic curve for the cooking vessel made of iron.
[0032]
Here, the horizontal axis of FIG. 3 shows the phase difference setting voltage Vset. As the phase difference setting voltage Vset increases, the phase difference between the inverter voltage Viv and the capacitor voltage Vc increases. For example, when the phase difference setting voltage Vset is 0V, it corresponds to a phase difference of 90 °, and when the phase difference setting voltage Vset is 4V, it corresponds to a phase difference of 130 °. When the phase difference is 90 °, the input power is set to, for example, 3 kW, and when the phase difference is 130 °, the input power is set to, for example, 200 W.
[0033]
The load state detection circuit 23 sets threshold values having a predetermined width for determining the load state, that is, threshold values Is1 and Is2 (Is1 <Is2) as shown in FIG. The threshold values Is1 and Is2 are compared with the value of the input current Iin detected by the input current detection circuit 22. Specifically, when the value of the input current Iin is lower than the threshold value Is1, the load state detection circuit 23 determines that the object to be heated placed on the top plate 1 is made of iron or non-magnetic stainless steel. Judge as a container. When the value of the input current Iin is between the threshold value Is1 and the threshold value Is2, it is determined that the object to be heated placed on the top plate 1 is an aluminum cooking container. Further, when the value of the input current Iin is larger than the threshold value Is2, it is determined that there is no load, and a detection signal is output.
[0034]
In FIG. 1, the timer circuit 24 is set to a predetermined timer time, for example, 3 seconds. When a detection signal is input from the load state detection circuit 23, the load is detected again by operating the initial circuit 21 after 3 seconds. Perform the action.
[0035]
On the other hand, a current transformer CT (2) is also provided between the common connection point of the IGBTs 10 and 11 (the output terminal of the inverter circuit 9) and the heating coil 2 with the current path between them as the primary conductor. The inverter current detection circuit 25 outputs a current detection signal of a voltage level corresponding to the inverter current based on the secondary side output of the current transformer CT (2), and converts the current detection signal into an A / D converter 26b. After converting into a digital value signal, the signal is applied to the phase difference setting circuit 18 to limit the maximum value of the inverter current. The power supply voltage detection circuit 28 detects the voltage of the AC power supply 6, converts the power supply voltage detection signal into a digital value signal by the A / D converter 26b, and supplies the digital value signal to the power amount detector 27.
[0036]
The power amount detection unit 27 integrates the input power by temporally integrating the input current, and supplies the integrated power value to a heated object detection unit 29 (corresponding to a heated object detection unit). The power amount detection unit 27 is configured to calculate the input power on the assumption that the power supply voltage is constant, and when the power supply voltage fluctuates, the power supply voltage signal supplied from the power supply voltage detection circuit 28 Is calculated in consideration of the input power.
[0037]
The voltage signal generation circuit 30 converts a change in the resistance value of the thermistor 4 into a voltage signal having a level corresponding to the temperature detected by the thermistor 4 and outputs the voltage signal. And given to the heated object temperature determination unit 32. The heated object temperature determining unit 32 generates a temperature signal indicating the actual temperature detected by the thermistor 4 (the temperature of the heated object) based on the voltage signal from the A / D converter 31. The signal is provided to the object-to-be-heated detection unit 29 and a heating power setting unit 33 described later.
[0038]
The heated object determination criterion storage unit 34 (corresponding to an information storage unit) stores the correlation between the integrated power value of the power amount detection unit 27 and the temperature detected by the thermistor 4 (the output of the heated object temperature determination unit 32). It is stored as determination reference value information to be described later for obtaining information on the heated object, and the determination reference value information is provided to the heated object detection unit 29.
[0039]
The object-to-be-heated detection unit 29 compares the determination reference value information stored in the object-to-be-heated determination storage unit 34, the integrated power value from the power amount detection unit 27, and the temperature signal from the object-to-be-heated determination unit 32. Based on the result of the comparison, information on the object to be heated (the type of cooking operation (for example, cooking of a pot, in which the heating target is water, fry cooking, in which the heating target is oil, etc.), the type and weight of the cooking container 3, and cooking This is for acquiring and outputting the degree of warpage of the bottom of the container 3 and the amount of food, and a specific example of acquiring the information will be described later.
[0040]
The operation / display unit 35 (corresponding to operation means) is used to set cooking conditions such as heating output (input power) and cooking time, to set a heating course that can be selected from a plurality of types, to start and stop heating, and the like. It is provided for performing the operation of, in addition to such operation functions, set heating output, cooking time, display of the heating cooking course, a function of displaying whether or not during the cooking operation, In addition, a function is set to display when the actual heating output is changed by the heating output control means 36 described later.
[0041]
In this case, as the heating cooking course, for example, a stir-fry cooking course, a fried food cooking course, and a boiling water course are set in addition to the normal heating course in which cooking is started at a constant heating output. Is equipped with a key switch (for example, a “fryer key”, “tempura key”, “boiler key”) for selecting each of the courses of stir-fry cooking, fry-cooking, and boiling water. There are also provided a start key and a stop key for starting and stopping the operation, an operation dial for setting a heating output and a cooking time, and the like. The normal heating course is automatically selected when the start key is operated.
[0042]
The heating output control means 36 comprises the heating power setting unit 33 and a heating power comparison circuit 37 receiving the output of the heating power setting unit 33. Among these, the heating power setting unit 33 receives the output from the heated object detection unit 29 and the setting output from the operation / display unit 35 as output control information, and outputs the output control information and the temperature from the heated object temperature determination unit 32. The control of the heating output by the heating coil 2 and the display control by the operation / display unit 35 are performed based on the signal. Specifically, the heating power setting unit 33 feeds back a setting output from the operation / display unit 35 (heating output according to set cooking conditions and a heating cooking course) and a temperature signal from the heated object temperature determining unit 32. It has a function of changing the set heating output based on the information on the object to be heated acquired by the object to be heated detector 29, and further operates the set heating output after the change. -A function to display on the display unit 35 is provided.
[0043]
In this case, the heating power setting unit 33 stores a plurality of types of heating output control patterns corresponding to the temperatures detected by the thermistor 4, and controls the plurality of types of heating output control in accordance with the setting output from the heated object detection unit 29. One of the patterns is selected. FIG. 4 shows a specific example of such a heating output control pattern. It should be noted that such a heating output control pattern may be in a form corresponding to the cooking time.
[0044]
That is, the heating output control pattern {circle around (1)} shown in FIG. 4A is a control pattern in which the overshoot of the heating temperature is suppressed, until the temperature detected by the thermistor 4 reaches the power suppression start temperature (for example, 140 ° C.). The maximum input power (for example, 3 kW) is maintained, and after reaching the power suppression start temperature, the input power is gradually reduced as the detected temperature increases, and the input power is reduced when the detected temperature reaches the control temperature Tcon. It is in the form of zero.
[0045]
The control temperature Tcon is set to, for example, 220 ° C. when a cooking course other than the stir-fry cooking course is set, and is set to 240 ° C. when the stir-fry cooking course is set. I have.
[0046]
The heating output control pattern {circle around (2)} shown in FIG. 4 (b) is a control pattern in which the heating speed (heating temperature rising speed) is prioritized, and the temperature detected by the thermistor 4 is a predetermined temperature (for example, 55 ° C.) from the control temperature Tcon. The maximum input power (3 kW) is maintained until the power suppression start temperature is reached, and after the power suppression start temperature is reached, the input power is gradually reduced as the detected temperature rises. The input power is set to zero when Tcon is reached.
[0047]
The heating output control pattern {circle around (3)} shown in FIG. 4 (c) is a control pattern in which the input power (heating output) is suppressed by a predetermined amount, and the temperature detected by the thermistor 4 is lower than the pattern {circle around (1)}. The predetermined input power (for example, 2 kW) that is lower than the maximum input power is maintained until the start temperature (for example, 80 ° C.) is reached, and after reaching the power suppression start temperature, the input power is reduced as the detected temperature rises. The input power is reduced gradually when the detected temperature reaches the control temperature Tcon.
[0048]
The heating output control pattern {circle around (4)} shown in FIG. 4 (d) is a control pattern for performing heating at the maximum input power more gently than the above-mentioned pattern {circle over (1)}. The maximum input power (3 kW) is maintained until a power suppression start temperature (for example, 100 ° C.) lower than (1) and higher than the heating output control pattern (3) is reached, and after reaching the power suppression start temperature, The input power is gradually reduced as the detected temperature rises, and the input power is set to zero when the detected temperature reaches the control temperature Tcon.
[0049]
Further, the heating power comparison circuit 37 includes a heating output control pattern selected by the heating power setting unit 33, a current detection signal supplied from the input current detection circuit 22 and the power supply voltage detection circuit 28 through the A / D conversion units 26a and 26b, and a power supply control signal. The input signal is compared with the actual input power indicated by the voltage signal, and the comparison output is supplied to the phase difference setting circuit 18. The phase difference setting circuit 18 receiving such a comparison output controls the input power so as to be in the selected heating output control pattern by outputting a phase difference setting voltage Vset corresponding to the comparison output.
[0050]
In this embodiment, the phase comparison circuit 15, the difference comparison circuit 17, the phase difference setting circuit 18, the VCO 19, the initial circuit 21, the load state detection circuit 23, the timer circuit 24, and the A / D converters 26a, 26b and 31 The power output detector 27, the object to be heated detector 29, the object to be heated temperature determination unit 32, the object to be heated determination reference storage unit 34, and the heating output control means 36 constitute an inverter output control circuit 38. The inverter output control circuit 38 is configured by a microcomputer (RISC microcomputer) having a CPU core of the RISC architecture.
[0051]
The object-to-be-heated detection unit 29 is configured to determine the reference value information from the object-to-be-heated determination storage unit 34, the integrated power value from the power amount detection unit 27, and the temperature signal (thermistor) Based on the result of the comparison with the information on the object to be heated (the type of the cooking operation, the type and weight of the cooking container 3, the degree of warping of the bottom of the cooking container 3, the amount of the food, etc.). Although the function to acquire is set, the principle of information acquisition will be described below.
[0052]
That is, the characteristic curve indicating the relationship between the integrated input power during the cooking operation (the integrated power value from the power amount detection unit 27) and the temperature detected by the thermistor 4 depends on the type of cooking and the degree of warpage of the bottom of the cooking container 3. It will be different depending on the situation. FIG. 5 shows a specific example of such a characteristic curve. The characteristic curve of FIG. 5 shows the relationship between the integrated input power and the detected temperature when five types of samples to be heated are heated on the top plate 1 with a constant input power. Examples of the sample of the object to be heated include a cooking container in a non-load state in which no object to be cooked is contained (characteristic curve is described as “empty firing”), and a cooking container 3 containing water (characteristic curve is described as “water load”). ), Cooking container 3 having no warp at the bottom and containing oil for tempura (characteristic curve is described as "no tempura pot warp"), cooking container having a warp of about 2 mm at the bottom and containing oil for tempura 3 (characteristic curve described as “tempura pot warpage (2 mm)”) and cooking container 3 containing a small amount of stir-fry oil (characteristic curve described as “vegetable stir fry”) were prepared.
[0053]
As can be understood from FIG. 5, in the case of “water load” (corresponding to the case where cooking in a pot is performed), the detected temperature rises slowly and linearly according to the increase in the integrated input power, and the “stir-fried vegetables” ”(Corresponding to the case where stir-fry cooking is performed), the detected temperature rises sharply as the integrated input power increases, and in the case of“ empty heating ”(the cooking container 3 is heated without load). Will rise even more rapidly than in the case of “fried vegetables”. In addition, in the case of “no tempura pan warp” and “tempura pan warp (2 mm)” (corresponding to the case where fried food is cooked), in any case, the detected temperature is a quadratic function according to the increase of the integrated input power. In the case of “tempura pan warpage (2 mm)”, the rise in the detected temperature tends to be delayed as compared with “no tempura pan warpage”. This tendency occurs when the bottom of the cooking container 3 is warped because the coefficient of thermal resistance between the cooking container 3 and the thermistor 4 increases.
[0054]
As a result of the existence of such characteristics, the type of cooking (pan cooking, fried food) can be determined by referring to the integrated input power during a period in which the temperature detected by the thermistor 4 rises by a predetermined temperature (for example, 25 deg. Shown in FIG. 5). It is possible to acquire information indicating whether or not the cooking container 3 is warped during cooking, fry cooking, and fry cooking.
[0055]
The object-to-be-heated detecting section 29 in the present embodiment acquires the above information by the following method in view of the characteristics shown in FIG.
That is, the object-to-be-heated detection unit 29 detects whether the object to be heated is the cooking container 3 containing a small amount of stir-fry oil by detecting the inclination of the temperature detected by the thermistor 4, that is, the cooking type is stir-fry. It is determined whether it is cooking. Specifically, the temperature detected by the thermistor 4 has passed a predetermined temperature measurement period in which the input power (heating output) is constant, for example, a preset measurement standby time (for example, 10 seconds) after the start of the cooking operation. If the temperature rises beyond a set temperature range (for example, 10 deg.) In a period until a predetermined time (for example, 20 seconds) elapses from the time, the heating target is the cooking container 3 containing a small amount of stir-fry oil. It is determined that the cooking type is stir-fry cooking. In addition, when the variation range of the detected temperature of the thermistor 4 during the temperature measurement period as described above is equal to or less than the set temperature range (10 deg.), It is determined that the cooking type is other than the cooking of stir-fry.
[0056]
When it is determined that the type of cooking is other than the cooking of the stir-fry, the heated object detection unit 29 determines the type of cooking as follows. That is, FIG. 6 shows a model of the relationship between the integrated input power and the temperature detected by the thermistor 4 during the actual cooking operation. The object-to-be-heated detecting unit 29 determines that the integrated input power in the predetermined period shown in FIG. 6, specifically, the temperature detected by the thermistor 4, indicates that a predetermined standby time (for example, 20 seconds) has elapsed after the start of the cooking operation. When the type of cooking is determined to be pot cooking or fried food cooking based on the magnitude of the integrated input power J obtained by time-integrating the input power during the period from the time when the temperature rises by 25 ° C. to the time of fried food cooking. Of the cooking container 3 is determined.
[0057]
For example, when the integrated input power J is 240 kW · s or more, it is determined that the object to be heated is a water load and the cooking type is pan cooking. When the integrated input power J is less than 170 kW · s, it is determined that the object to be heated is the cooking container 3 containing the oil for the tempura and the cooking type is fried food cooking. It is determined that the bottom is not warped. Further, when the integrated input power J is 170 kW · s or more and less than 240 kW · s, it is determined that the object to be heated is the cooking container 3 containing the oil for the tempura and the cooking type is fried food cooking, It is determined that the bottom of the cooking container 3 is warped.
[0058]
In addition, whether or not the bottom of the cooking container 3 is warped at the time of cooking the fried food is determined based on the relationship between the integrated input power from a predetermined time after the start of the cooking operation and the increase in the detected temperature of the thermistor 4. It is also possible. Specifically, when the integrated input power from a predetermined time after the start of the cooking operation (for example, 10 seconds) has reached a predetermined value, the rise in the detected temperature of the thermistor 4 is equal to or higher than a predetermined threshold temperature. In this case, it can be determined that the bottom of the cooking container 3 is warped.
[0059]
The object-to-be-heated detecting unit 29 determines whether the cooking type is pan cooking or other cooking, by determining the linearity of a characteristic curve indicating the relationship between the integrated input power during the cooking operation and the temperature detected by the thermistor 4. The configuration is also determined by the method referred to. That is, the object-to-be-heated detecting unit 29 sets the temperature detected by the thermistor 4 at the time when a predetermined standby time (for example, 20 seconds) elapses after the start of the cooking operation as the reference temperature, and sets the integrated input power at that time. Remember. Further, the object-to-be-heated detecting unit 29 sequentially stores the integrated input power at each timing when the temperature detected by the thermistor 4 rises from the reference temperature in steps of 5 ° C. Then, the integrated input power during the period in which the detected temperature is increased by, for example, 10 ° C. is compared over a plurality of periods, and based on the comparison result, the linearity of the above-described characteristic curve is checked. It is determined whether or not the load is applied (whether or not the cooking type is hot pot cooking).
[0060]
A specific example of such determination is as follows. That is, the characteristic curve of FIG. 7 shows the relationship between the integrated input power and the temperature detected by the thermistor 4 when the object to be heated is the cooking container 3 having a warp of about 2 mm at the bottom and containing oil for tempura. It is shown. In the example of FIG. 7, the integrated input power at each time point when the temperature detected by the thermistor 4 rises from the reference temperature (41 ° C.) in steps of 5 ° C. is obtained, and the integrated input power during the period in which the detected temperature rises by 10 ° C. As data indicating the input power,
ΔT1 = (53−20) × 3 kW · s
ΔT2 = (66−36) × 3 kW · s
ΔT3 = (73−53) × 3 kW · s
ΔT4 = (86−66) × 3 kW · s
Is obtained.
[0061]
By comparing the value 特性 Δa (= ΔT1 + ΔT2) obtained by adding the first two of such data with the value ΣΔb (= ΔT3 + ΔT4) obtained by adding the latter two, the linearity of the characteristic curve is examined. Thus, it is determined whether the object to be heated has a water load. For example,
ΣΔa × 0.9 ≦ ΣΔb
Is determined to be a water load when the relationship is satisfied. However, in the example of FIG. 7, ΣΔa = 63 × 3 kW · s and ΣΔb = 40 × 3 kW · s,
ΣΔa × 0.9> ΣΔb
Therefore, it is determined that the load is other than the water load.
[0062]
The heated object determination criterion storage unit 34 stores determination criterion value information (power integrated value by the power amount detection unit 27 (integrated input value) required for performing various determinations as described above in the heated object detection unit 29. Power) and various correlations between the temperatures detected by the thermistor 4).
[0063]
FIGS. 8 to 13 show parts related to the gist of the present invention in the contents of control by the inverter output control circuit 38, which will be described below together with related operations. In the following description, the heating output control patterns (1) to (4) are simply referred to as control patterns (1) to (4), respectively.
[0064]
FIG. 8 shows the entire control contents. In FIG. 8, in the initial state, the control pattern (1) (see FIG. 4A) is set in the object-to-be-heated detection section 29 (step S0), whereby the heating power in the heating output control means 36 is set. The setting unit 33 enters a state where the control pattern (1) is selected. In this initial setting state, a normal heating course, a stir fry cooking course, a fried food cooking course, and a start key, a “stir fry key”, a “tempura key”, and a “boiler key” provided on the operation / display unit 35 are operated. A cooking operation using any of the boiling water courses is started.
[0065]
At the start of the cooking operation using the normal heating course, the control temperature Tcon is set to 220 ° C. (step S1), and the load determination processing routine S2 is executed. At the start of the cooking operation using the stir-fry cooking course, the control temperature Tcon is set to 240 ° C. (step S3), and the load determination processing routine S2 is executed. After the execution of the load determination processing routine S2, a step S4 for setting the control pattern (2) (see FIG. 4B) in the object-to-be-heated detecting section 29 is executed, whereby the heating power setting section is executed. Reference numeral 33 indicates a state in which the control pattern (2) is selected.
[0066]
At the start of the cooking operation by the fried food cooking course, after executing the load determination processing routine S5 having the same contents as the load determination processing routine S2, the tempura control routine S6 is executed. Be executed. Of these control routines S6 and S7, the tempura control routine S6 is a well-known one that performs control such as reducing the heating output when the temperature detected by the thermistor 4 reaches the set temperature. The description is omitted because it is not directly related. Further, the water heater control routine S7 is for performing control to prevent a situation in which water to be heated is spilled when boiling, and the contents thereof are shown in FIG.
[0067]
In FIG. 9, the water heater control routine S7 is started in a state where the heating pattern (1) is set (step A1), and the heating operation is performed with the maximum heating output, that is, the maximum input power (3 kW) ( Step A2). Thereafter, the process waits until a predetermined time (for example, 20 seconds) elapses (step A3). When the time elapses, the temperature detected by the thermistor 4 is stored as Ta (step A4). Thereafter, the calculation of the integrated input power is started in the electric energy detection unit 27 (step A5), and the operation waits until the temperature detected by the thermistor 4 reaches the first target temperature, for example, 65 ° C. (step A6).
[0068]
When the detected temperature reaches 65 ° C., the input power is reduced to 2 kW (step A7), and thereafter, the process stands by until the temperature detected by the thermistor 4 reaches the second target temperature, for example, 90 ° C. (step A8). . Then, when the detected temperature reaches 90 ° C., the input power is reduced to 1 kW (step A9).
As a result of the above control being performed, the input power is gradually reduced as the temperature detected by the thermistor 4 increases.
[0069]
When the input power is reduced to 1 kW as described above, the process waits until a predetermined time (for example, 20 seconds) elapses (step A10). When the time elapses, the temperature detected by the thermistor 4 is stored as Tb. (Step A11). Next, the electric energy detection unit 27 calculates the integrated input electric power J in a period from 20 seconds after the start of the heating operation to the present time (a period in which the detected temperature has risen from Ta to Tb) (step A12).
[0070]
Thereafter, based on the calculated integrated input power J and the detected temperatures Ta and Tb detected by the thermistor 4, the temperature of the water in the cooking vessel 3, which is the object to be heated, is raised to a predetermined target heating temperature (100 ° C.). A13 for estimating the input power amount required for is executed. In step A13, the input power amount is calculated as “1 kW heating time (t1 kW)”, which is how long the input power is kept at 1 kW to keep the object to be heated to the target heating temperature. The calculation is performed by the following equation.
t1kW = (J / 1) × {(100−Tb} / (Tb−Ta))
Since the unit of “1” in the term (J / 1) is [kW] and the unit of the integrated input power J is [kW · S], the unit of t1kW is [s]. That is, [sec].
[0071]
After calculating t1 kW, the input power (heating output) is reduced to 1 kW, and then the apparatus waits until t1 kW [second] elapses (step A14). When t1 kW [second] elapses, the input power is kept warm (input A). For example, it is reduced to 300 W) (step A15). Thereafter, the process waits until the set time has elapsed since the input power was changed to 300 W (step A16), and when the set time has elapsed, the water heater control routine S5 ends.
[0072]
In short, as a result of performing such control, in a state in which heating and cooking is performed by the water heater course, that is, in a state in which input power (heating output) is controlled in the water heater control mode, the object to be heated (the cooking container 3) is not heated. The input power amount (heating output amount) required to raise the temperature of water (eg, water stored in a kettle) to 100 ° C., which is the target heating benefit, is predicted, and the heating output control unit 36 uses the prediction result based on the prediction result. To control the input power. For this reason, immediately before boiling of water, the input power is automatically suppressed, and a heating operation with excessive input power is performed just before the boiling of water, and boiling water spills. It is possible to prevent inviting situations. In addition, the configuration is such that the input power is gradually reduced in accordance with the rise in the temperature of the object to be heated, which is advantageous in reliably preventing boiling water from spilling over.
[0073]
On the other hand, the contents of the load determination processing routine S2 are shown in FIGS. That is, after the start of the load determination processing routine S2, first, as shown in FIG. 10, the start temperature T (the temperature at the start of the cooking operation) is detected based on the temperature signal from the thermistor 4 (step E1). Next, it is determined whether or not the starting temperature T is equal to or higher than the set control temperature (Tcon) (step E2). If the temperature is equal to or higher than the control temperature, the aforementioned step S4 for setting the control pattern (2) is performed. (See FIG. 8).
[0074]
On the other hand, when the starting temperature T is equal to or lower than the control temperature, different control is performed according to the level of the starting temperature T. Specifically, when T ≦ 80 ° C., the control process (A) shown in FIG. 11 is executed, and when 80 ° C. <T <150 ° C., the control process (B) shown in FIG. 12 is executed. , 150 ° C. ≦ T, the control process (C) shown in FIG. 13 is executed.
[0075]
In FIG. 11 showing the contents of the control processing (A) executed when T ≦ 80 ° C., first, a step of setting a control pattern (1) (see FIG. 4A) in the heated object detection unit 29. B1 is executed, whereby the heating power setting unit 33 starts the cooking operation in a state where the control pattern (1) is selected.
[0076]
After the start of the cooking operation, the inclination of the temperature detected by the thermistor 4 is detected in order to determine whether the object to be heated is the cooking container 3 containing a small amount of stir-fry oil (step B2). The specific method of detecting the gradient of the detected temperature has been described above. Next, based on the detected temperature gradient, it is determined whether or not the object to be heated is the cooking container 3 containing a small amount of stir-fry oil (whether or not the cooking type is stir-fry cooking) (step B3).
[0077]
If "YES" is determined in the step S, a control pattern (3) (see FIG. 4 (c)) is set in the heated object detection unit 29 (step B4), whereby the heating power setting unit 33 is set. However, the cooking operation is continued in a state where the control pattern (3) is selected, that is, in a state where the input power is suppressed.
[0078]
Thereafter, it is determined whether the slope of the temperature detected by the thermistor 4 is gentler than a predetermined reference slope (step B5). If the slope is gentle, that is, if the input power is considered to be insufficient, Is to return to the control pattern (1) in the object-to-be-heated detecting section 29 (step B6), whereby the heating power setting section 33 performs the cooking operation while controlling the input power based on the control pattern (1). Will be continued.
[0079]
If the detected temperature gradient is equal to or higher than the reference gradient, the cooking operation in the control pattern (3) is continued until the temperature detected by the thermistor 4 becomes equal to or higher than the control temperature (step B7). When the temperature is equal to or higher than the control temperature, the process proceeds to step S4 (see FIG. 8) for setting the control pattern (2).
[0080]
After the execution of the above-described step B6, that is, in a state where the cooking operation in the control pattern (1) has been performed, it is determined whether or not the temperature detected by the thermistor 4 has become equal to or higher than the control temperature (step B8), and "YES". When the determination is made, the process proceeds to step S4 (see FIG. 8) for setting the control pattern (2).
[0081]
On the other hand, when the temperature detected by the thermistor 4 has not reached the control temperature, the process waits until the detected temperature becomes 180 ° C. or higher (step B9). It is determined again whether or not the above has occurred (step B10). It should be noted that at the stage where this step B10 is first executed, the relationship of the detected temperature <the control temperature is satisfied, so that "NO" is determined in the step B10.
[0082]
If "NO" is determined in the step B10, it is determined whether or not the slope of the temperature detected by the thermistor 4 is equal to or less than a preset slope, for example, 2 ° C / 10s (step B11). When it is determined, step B10 is executed again. That is, step B11 for determining the gradient of the detected temperature is executed when the detected temperature is equal to or higher than 180 ° C. and lower than the control temperature. If "YES" is determined in any of steps B10 and B11, the process proceeds to step S4 (see FIG. 8) for setting control pattern (2).
[0083]
On the other hand, if "NO" is determined in the step B3, that is, if it is determined that the cooking type is other than the stir-fry cooking, it is determined whether the object to be heated is a water load (step B12). . Such a determination is made by, for example, a method of referring to the linearity of a characteristic curve indicating the relationship between the integrated input power during the cooking operation and the temperature detected by the thermistor 4 (the details thereof are described above). Then, when it is determined that it is a water load, that is, when it is determined that the cooking type is pan cooking, the control in and after step B8 is executed.
[0084]
On the other hand, when it is determined that the load is not the water load, the detection of the inclination of the detected temperature by the thermistor 4 ends (step B13). The state where it is determined that the load is not the water load is a state where the cooking type is assumed to be fried food cooking. Then, after execution of step B13, the integrated input power J becomes
170 kW · s ≦ J <240 kW · s
Is determined.
[0085]
Here, as described above, when the integrated input power J is 170 kW · s or more and less than 240 kW · s, the object to be heated is the cooking container 3 containing the oil for the tempura and the cooking type is fried food cooking. At the same time, it is possible to determine that the bottom of the cooking container 3 is warped. If the determination is made as described above ("YES" in step B14), the control pattern {circle around (3)} (FIG. 4 (c)) (step B15), so that the heating power setting unit 33 continues the cooking operation in a state where the control pattern (3) is selected, that is, in a state where the input power is suppressed. become.
[0086]
Thereafter, it is determined whether the input power (heating output) has decreased by a predetermined amount or more from the input power up to that time (step B16). If not, whether the temperature detected by the thermistor 4 has exceeded the control temperature or not is determined. It is determined whether or not it is (step B17). If the detected temperature is equal to or higher than the control temperature, the process proceeds to step S4 (see FIG. 8) for setting the control pattern (2). If the detected temperature is lower than the control temperature, step B16 is re-executed. I do.
[0087]
When the input power has dropped by a predetermined amount or more from the previous input power, the actual heating output display on the operation / display unit 35 is changed (step B18), and the heating output (input power) changing operation by the user is performed. It is determined whether or not it has been touched (step B19). If the operation has not been performed, the process proceeds to step B17. If the operation has been performed, the original control pattern (1) is reset in the heated object detection unit 29 (step B20). Accordingly, the heating power setting unit 33 returns to the state where the control pattern (1) is selected, that is, the input power, and continues the cooking operation. After the execution of step B20, the actual heating output display on the operation / display unit 35 is returned to the original state (step B21), and thereafter, the process proceeds to step B17.
[0088]
On the other hand, if it is determined “NO” in step B14, that is, if the object to be heated is the cooking container 3 containing the oil for the tempura and it is assumed that the bottom of the cooking container 3 is not warped, Then, the control pattern {circle around (1)} (see FIG. 4 (a)) or the control pattern {circle around (4)} (see FIG. 4 (d)) is set in the object-to-be-heated detecting section 29 (step B22). Execute control. In step B22, for example, when the integrated input power during a period in which the temperature detected by the thermistor 4 rises by a predetermined temperature width after the start of the cooking operation is equal to or higher than a predetermined threshold power (that is, when the load amount is relatively large). If the integrated input power is less than the threshold power, the control pattern (4) is selected.
[0089]
In FIG. 12 showing the contents of the control processing (B) executed when 80 ° C. <T <150 ° C., first, the control pattern {circle around (4)} (see FIG. The setting step C1 is executed, whereby the heating power setting unit 33 starts the cooking operation in a state where the control pattern (4) is selected.
[0090]
After the start of the cooking operation, the inclination of the temperature detected by the thermistor 4 is detected in order to determine whether or not the object to be heated is the cooking container 3 containing a small amount of stir-fry oil (step C2). The specific method of detecting the gradient of the detected temperature has been described above. Next, based on the detected temperature gradient, it is determined whether the object to be heated is the cooking container 3 containing a small amount of stir-fry oil (whether or not the cooking type is stir-fry cooking) (step C3).
[0091]
If it is determined that the cooking type is stir-fry cooking, a control pattern {circle around (3)} (see FIG. 4 (c)) is set in the heated object detection unit 29 (step C4), thereby setting the heating power. The unit 33 continues the cooking operation in a state where the control pattern (3) is selected, that is, in a state where the input power is suppressed. Thereafter, the cooking operation in the control pattern (3) is continued until the temperature detected by the thermistor 4 becomes equal to or higher than the control temperature (step C5). When the detected temperature becomes higher than the control temperature, the control pattern (2) The process proceeds to step S4 (see FIG. 8) for setting ▼.
[0092]
On the other hand, if "NO" is determined in step C3, that is, if it is determined that the cooking type is other than the stir-fry cooking, it is determined whether or not the object to be heated is a warp pot that is fried. It is determined whether or not the bottom of the cooking container 3 in which the tempura oil is stored is warped) (Step C6). ▼ (See FIG. 4 (c)) Set to step C4 where it is determined that the pan is not a warp pan (case where it is assumed that pan cooking or fry cooking is performed in a non-warped cooking container) ), The process proceeds to step C7 for setting the control pattern (1) (see FIG. 4A).
[0093]
It should be noted that the determination as to whether or not such a warped pot is made is performed in the object-to-be-heated detecting section 29 in the following manner. That is, when the integrated input power J 'from a predetermined time after the start of the cooking operation (for example, after 10 seconds) has reached a predetermined value, the rise value t (deg.) Of the detected temperature of the thermistor 4 from the predetermined time is increased. When the temperature is equal to or higher than the predetermined threshold temperature P, it can be determined that the bottom of the cooking container 3 is warped. FIG. 14 shows an example of a data table used for such determination (this is stored as determination value reference information in the heated object determination reference storage unit 34).
[0094]
The terms (A) and (B) in FIG. 14 show the threshold values of the states where the integrated input power J ′ is 100 kW · s, 120 kW · s, 150 kW · s, 200 kW · s, 250 kW · s, and 300 kW · s. Value temperature P is 14 deg. , 20 deg. , 35 deg. , 70 deg. 80 deg. , 100 deg. Is shown. When the relationship of t ≧ P is satisfied, it is determined that the cooking container 3 such as a fryer or a frying pan is almost in a no-load (empty-fired) state in which the object to be cooked is hardly contained. When control pattern {circle around (3)} is set and the relationship of t <P is established, it is determined that an object to be cooked is contained in the cooking container 3, whereby the control pattern {circle around (1)} is set in step C7. Will be.
[0095]
Here, the control pattern (1) or (3) is set based on the result of determination as to whether or not there is no load (dry heating). The relationship between the value t and the threshold temperature P depends on the condition as shown in FIG. 14C (the state in which a cooking object such as vegetables is contained in a frying pan, or the state in which the cooking vessel 3 is a non-warped tempura pan). Is assumed, and a control pattern (3) is set when the condition of the item (B) is satisfied, and a control pattern (1) is set only when the condition of the item (C) is satisfied. When both of these conditions are not satisfied, a configuration in which the control pattern is not changed and set (a configuration in which the control pattern (4) is maintained assuming a warp pot) may be adopted. Further, a condition as shown in FIG. 14D is added, and when such a condition is satisfied (for example, a state in which water is contained in the cooking container 3), the control pattern {circle around (1)}. It is also possible to adopt a configuration for setting ▼.
[0096]
After the execution of step C7, the process stands by until the temperature detected by the thermistor 4 becomes 180 ° C. or higher (step C8). When the temperature becomes 180 ° C. or higher, it is determined again whether the detected temperature has become higher than the control temperature (step C8). C9). It should be noted that at the stage where this step C9 is first executed, the relationship of the detected temperature <the control temperature is satisfied, so that "NO" is determined in the step C9.
[0097]
If "NO" is determined in the step C9, it is determined whether or not the slope of the temperature detected by the thermistor 4 is equal to or less than a preset slope, for example, 2 ° C / 10s (step C10). ", The step C9 is executed again. That is, step C10 for determining the inclination of the detected temperature is executed when the detected temperature is equal to or higher than 180 ° C. and lower than the control temperature. If "YES" is determined in any of steps C9 and C10, the process proceeds to step S4 (see FIG. 8) for setting control pattern (2).
[0098]
In FIG. 13 showing the contents of the control process (C) executed when 150 ° C. ≦ T, first, a step of setting a control pattern (1) (see FIG. 4A) in the heated object detection unit 29. D1 is executed, so that the heating power setting unit 33 starts the cooking operation with the control pattern (1) selected. Thereafter, the process waits until the temperature detected by the thermistor 4 becomes higher than the control temperature (step D2). When the temperature becomes higher than the control temperature, the process proceeds to step S4 (see FIG. 8) for setting the control pattern (2). Transition.
[0099]
Although not shown in FIGS. 10 to 13 above, in the execution period of the cooking operation according to the control pattern {circle around (3)} (that is, the period during which the input power is suppressed), the control pattern is established when the following conditions are satisfied. It is configured to shift to the state of performing the cooking operation according to (1). That is, when the temperature detected by the thermistor decreases by a predetermined temperature or more during a predetermined period after shifting to the cooking operation according to the control pattern (3), the process shifts to the cooking operation according to the control pattern (1).
[0100]
When the temperature detected by the thermistor 4 is 40 ° C. or more and 120 ° C. or less, 10 deg. The integrated input power in increments was calculated, and conditions such as a data table shown in FIG. 15 (stored in the heated object determination reference storage unit 34 as determination value reference information) in each temperature zone were obtained. Sometimes, the operation shifts to the cooking operation according to the control pattern (1). In the data table of FIG. 14, condition (A) corresponds to a state in which fried food is cooked in the cooking container 3 having no warped bottom, and condition (B) corresponds to a state in which hot pot cooking is performed. Is equivalent to
[0101]
In short, as a result of such control, the following operations and effects can be obtained.
That is, at the time of the cooking operation in which the cooking container 3 is induction-heated by the heating coil 2, the input power (heating output) at that time is integrated by the power amount detection unit 27, and the object to be heated (the cooking container 3 and its storage material). Is detected by the thermistor 4. The integrated input power by the power amount detection unit 27 corresponds to the energy actually consumed for heating the object to be heated, and the temperature detected by the thermistor 4 indicates the type of cooking operation (specifically, Are, for example, pot cooking in which the heating target is water, fried food cooking in which the heating target is oil, the type and weight of the cooking container 3 such as a pot, and the degree of warping of the bottom of the cooking container 3 (the cooking container 3 and the thermistor 4). And the amount of food to be cooked. Therefore, the correlation between such integrated input power and the detected temperature differs depending on the type of cooking operation, the type and weight of the cooking container 3, the degree of warpage of the bottom of the cooking container 3, the amount of food, and the like. Such a correlation is stored in the heated object determination reference storage unit 34 as determination reference value information.
[0102]
Then, in the heated object detection unit 29, information on the heated object is obtained based on a result of comparing the determination reference value information stored in the heated object determination reference storage unit 34 with the integrated input power and the detected temperature. More specifically, information indicating the type of cooking (stir-fried cooking, pan cooking, fried food cooking), and information on whether or not the bottom of the cooking container 3 is warped in the case of fried food cooking are obtained and output. I will do it. In the heating output control means 36, the output from the heated object detection unit 29 (information on the heated object) and the setting output from the operation / display unit 35 (cooking conditions such as heating output) are output control information. In addition to this, an operation of controlling the input power (heating output by the heating coil 2) based on the output control information is performed.
[0103]
Accordingly, since the temperature of the object to be heated is detected via the top plate 1, the error of the detected temperature increases, and the integrated input power by the power amount detection unit 27, that is, the heating of the object to be heated, Therefore, it is possible to optimally control the input power based on the phase relationship between the energy actually consumed and the temperature detected by the thermistor 4, thereby improving the cooking performance. .
[0104]
In this case, when the information that the bottom of the cooking container 3 is warped is acquired in the state where the fried food is being cooked, the control for automatically suppressing the input power is performed. For this reason, even in a situation where, for example, the cooking of fried food such as a tempura is mistakenly started by setting the normal heating course, the temperature of the oil in the cooking vessel 3 does not rise unnecessarily.
[0105]
Further, the heating power setting unit 33 in the heating output control means 36 stores a plurality of types of heating output control patterns (1) to (4) corresponding to the temperature detected by the thermistor 4, and the heating object detection unit 29 , Any one of the heating output control patterns (1) to (4) is selected according to the output from the controller, and the input power is controlled based on the selected heating output control pattern. As a result, by appropriately setting a plurality of types of heating output control patterns (1) to (4) in advance, the heating output can be optimally controlled.
[0106]
The object-to-be-heated detecting section 29 is configured to determine whether or not the stored object in the cooking container is water based on the curvature of a characteristic curve indicating the relationship between the integrated input power and the temperature detected by the thermistor 4. Thus, it is possible to accurately acquire information as to whether the type of cooking operation is pan cooking or other cooking.
[0107]
When the actual heating output is changed by the heating output control means 36 during the cooking operation, the set heating output in the state displayed on the operation / display unit 35 is changed to the changed heating output. On the user's side, the operation of correcting the heating output in accordance with the actual progress of the cooking operation can be performed at its own discretion. That is, for example, when the heating output control means 36 performs control to reduce the heating output during fried food cooking, when the user determines that such output reduction control is unnecessary, an operation to increase the heating output is performed. This is useful when actually cooking.
[0108]
The operation / display section 35 is provided with a stir fry key for selecting a stir fry cooking course as an operation section. When the stir fry cooking course is selected by the stir fry key, the heating output control means 36 is provided. However, since the configuration is such that the temperature of the object to be heated is controlled to be higher than that during normal heating, it is possible to effectively perform stir-fry cooking that requires heating at a high temperature. In addition, such a function of selecting a stir-fry cooking course can be set irrespective of the configuration described in claim 1 of the present invention.
[0109]
(Other embodiments)
The present invention is not limited to the above-described embodiment, but can be modified or expanded as described below.
A configuration in which the object-to-be-heated detection unit 29 acquires information about the object to be heated based on the integrated input power of the power amount detection unit 27 each time the temperature detected by the thermistor 4 changes by a predetermined amount, or a power amount detection unit The information about the object to be heated may be acquired based on the temperature detected by the thermistor 4 every time the integrated input power by the sensor 27 changes by a predetermined amount. According to this configuration, the operation of acquiring information about the object to be heated is performed every time the temperature detected by the thermistor 4 changes by a predetermined amount, or every time the integrated input power by the power amount detection unit 27 changes by a predetermined amount, Since the repetition is performed every time, it is useful in performing the optimal control of the heating output.
[0110]
【The invention's effect】
As is apparent from the above description, the present invention employs a temperature detection unit that detects a temperature of an object to be heated through a top plate in order to detect the temperature of the object to be heated. The type of cooking, the degree of warping of the bottom of the cooking vessel, etc.) are obtained based on the correlation between the input power by the power integrating means or the integrated value of the input power and the temperature detected by the temperature detecting means. Even when the temperature detection accuracy of the object is not sufficiently obtained, it is possible to significantly improve the cooking performance.
[Brief description of the drawings]
FIG. 1 is an overall electrical configuration diagram showing one embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a main part.
FIG. 3 is a characteristic diagram for explaining the content of a detection operation by a load state detection circuit.
FIG. 4 is a diagram showing a specific example of a heating output control pattern.
FIG. 5 is a characteristic curve diagram showing a relationship between integrated input power during a cooking operation and a temperature detected by a thermistor.
FIG. 6 is a characteristic diagram showing a model of a relationship between integrated input power and a temperature detected by a thermist 4 during an actual cooking operation.
FIG. 7 is a characteristic diagram showing a relationship between the integrated input power and the temperature detected by the thermistor 4 when a cooking container having a warped bottom and containing oil for tempura is heated.
FIG. 8 is a flowchart showing control contents, part 1
FIG. 9 is a flowchart showing control contents, part 2
FIG. 10 is a flowchart showing control contents, Part 3
FIG. 11 is a flowchart showing control contents, Part 4
FIG. 12 is a flowchart showing control contents, part 5
FIG. 13 is a flowchart showing control contents, part 6;
FIG. 14 is a diagram illustrating an example of a data table used to determine a state in which the bottom of the cooking container is warped.
FIG. 15 is a diagram showing an example of a data table used when changing and setting a heating control pattern.
[Explanation of symbols]
1 is a top plate, 2 is a heating coil (induction heating means), 3 is a cooking vessel, 4 is a thermistor (temperature detection means), 9 is an inverter circuit (induction heating means), 23 is a load state detection circuit, and 27 is an electric energy. A detecting unit (power integrating means); 29, a heated object detecting unit (heated object detecting means); 32, a heated object temperature determining unit; 33, a thermal power setting unit; 34, a heated object determining reference storage unit (information storage) Means, 35 is an operation / display unit (operation means), 36 is a heating output control means, 37 is a thermal power comparison circuit, and 38 is an inverter output control circuit.

Claims (10)

A top plate on which the cooking container is placed,
A heating coil for induction heating the cooking vessel and an induction heating means comprising an inverter circuit for supplying a high-frequency current to the heating coil;
Operating means for setting cooking conditions such as heating output by the induction heating means,
Power integration means for integrating the input power or input current of the induction heating means,
Temperature detection means for detecting the temperature of the object to be heated via the top plate,
Information storage means storing the correlation between the integrated value by the power integration means and the temperature detected by the temperature detection means as determination reference value information for obtaining information on the object to be heated,
Heated object which acquires and outputs information about the object to be heated based on the result of comparing the judgment reference value information stored in the information storage means with the integrated value by the power integrating means and the temperature detected by the temperature detecting means. Object detection means,
Heating output control means for receiving the output from the heated object detection means and the setting output by the operation means as output control information, and performing an operation of controlling the heating output by the induction heating means based on the output control information. An induction heating cooker comprising: The heating output control means stores a plurality of types of heating output control patterns corresponding to the temperature detected by the temperature detection means or the cooking time, and the plurality of types of heating outputs are controlled in accordance with an output from the object to be heated detection means. 2. The induction heating cooker according to claim 1, wherein any one of the output control patterns is selected, and the heating output by the induction heating means is controlled based on the selected heating output control pattern. The object-to-be-heated detecting means is configured to determine a type of a stored item in a cooking container based on a curvature of a characteristic curve indicating a relationship between an integrated value by the power integrating means and a temperature detected by the temperature detecting means. The induction heating cooker according to claim 1 or 2, The object-to-be-heated detecting means includes a change amount of an integrated value by the power integrating means corresponding to a change amount per unit time of the detected temperature by the temperature detecting means, or a unit value of the integrated value by the power integrating means per unit time. The induction heating cooker according to any one of claims 1 to 3, wherein information about the object to be heated is acquired based on a relationship between the amount of change in the temperature detected by the temperature detecting means and the amount of change in the temperature corresponding to the amount of change. . The configuration in which the object-to-be-heated detecting means acquires information about the object to be heated based on the integrated value of the power integrating means each time the temperature detected by the temperature detecting means changes by a predetermined amount, or The induction heating according to any one of claims 1 to 4, wherein each time the integrated value changes by a predetermined amount, information on the object to be heated is acquired based on the temperature detected by the temperature detecting means. Cooking device. A control mode for performing water heating is set in the heating output control means,
In the state where the control mode for boiling water is selected, the object-to-be-heated detecting means raises the object-to-be-heated to a predetermined target heating temperature based on the detected temperature of the temperature detecting means and the integrated value of the power integrating means. The induction heating according to any one of claims 1 to 5, wherein a heating output amount necessary for raising the temperature is predicted, and the prediction result is provided as output control information to the heating output control means. Cooking device. The induction heating cooker according to claim 6,
The induction heating cooker is characterized in that the control mode for boiling water is a control mode in which the heating output by the induction heating means is gradually reduced in accordance with an increase in the temperature detected by the temperature detection means. The function of displaying the set heating output and a function of displaying the actual heating output when the actual heating output is changed by the heating output control means, are provided in the operating means. 8. The induction heating cooker according to any one of 7. The operating means is provided with an operating unit for selecting a stir-fry cooking course,
9. The heating output control means controls the temperature of the object to be heated so that the temperature of the object to be heated is higher than that during normal heating when the stir-fry cooking course is selected. Induction heating cooker. The induction heating cooker according to claim 9,
In the operating means, in addition to the stir fry cooking course selection function, a heating output setting function, a fried cooking course selection function is set,
The heating output control means, in the state where the stir-fry cooking course is selected, the temperature of the object to be heated is higher than the state where the heating output is set by the heating output setting function and the state where the fried food cooking course is selected. The induction heating cooker according to any one of the preceding claims, wherein the induction heating cooker is controlled to be controlled as follows.

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