Heating Regulator

Abstract

To provide a heating cooker capable of decreasing heating output before reaching boiling point.SOLUTION: A disclosed heating cooker includes: heating means for heating a cooking container; temperature detection means that directly or indirectly detects the temperature of the cooking container; calculation means that differentiates the temperature detected over time by the temperature detection means at every predetermined detect time interval and calculates temperature gradient; and control means that is configured so as to, after the difference between the temperature gradient calculated by the calculation means and the temperature gradient set as the maximum value has reached a first predetermined value, lower the heating amount of the heating means before the temperature gradient of the boiling state exceeds a second predetermined value, which is the difference between the temperature gradient of the boiling state and the temperature gradient set as the maximum value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a cooking appliance. [Background technology]

[0002] When cooking stews in a cooking appliance, the conventional cooking process is divided into a first process, from the start of heating until boiling, and a second process, in which the heating output is reduced after boiling and heating continues.A boiling detection method is used to detect the boiling state as the condition for transitioning from the first process to the second process.

[0003] Patent Document 1 discloses an electromagnetic cooker that is less susceptible to the influence of electrical noise when detecting boiling. This induction cooker is equipped with a temperature detection unit located below the food placement unit, and a heating control unit that differentiates the temperature detected by the temperature detection unit at each predetermined time interval with respect to time and calculates a moving average value of the differentiated values ​​for a predetermined number of consecutive times, and after the temperature detection unit detects a temperature exceeding a predetermined value, uses the moving average value of the differentiated values ​​at the time the predetermined value is detected as a comparison reference value, and determines that the food has boiled when it obtains a moving average value of the differentiated values ​​that is lower than the comparison reference value by a predetermined ratio. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-268951 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a cooking device that reduces heating output before boiling is reached. [Means for solving the problem]

[0006] The cooking device of the present disclosure comprises a heating means for heating a cooking container, a temperature detection means for directly or indirectly detecting the temperature of the cooking container, a temperature gradient calculation means for calculating a temperature gradient by subtracting the temperature detected over time by the temperature detection means at predetermined detection time intervals, and a control means for reducing the amount of heat generated by the heating means after the difference between the temperature gradient calculated by the temperature gradient calculation means and a maximum temperature gradient set as the maximum value becomes equal to or greater than a first predetermined value, but before the difference exceeds a second predetermined value, which is the difference between the temperature gradient in a boiling state and the maximum temperature gradient. [Effects of the Invention]

[0007] The cooking device of the present disclosure reduces the amount of heat from the heating means after the difference in temperature gradient from the maximum temperature gradient reaches a first predetermined value or more, but before it exceeds a second predetermined value, which is the difference in temperature gradient at the boiling state from the maximum temperature gradient. This ensures that the heating output can be reduced before the boiling state is reached. Therefore, the possibility of splashing and boiling over can be reduced more than with the boiling detection method. [Brief explanation of the drawings]

[0008] [Figure 1] Overall configuration diagram of a heating cooker according to the first embodiment [Figure 2] FIG. 10 is a diagram showing calculated values ​​of temperature gradients of a cooking device according to the first embodiment. [Figure 3] 1 is a flowchart showing the control of stewing cooking in a cooking device according to the first embodiment. [Figure 4] FIG. 10 is a characteristic diagram showing the relationship between the temperature gradient, the heating output value, and time during stewing in the heating cooker according to the first embodiment. [Figure 5] FIG. 10 is a characteristic diagram showing the relationship between the temperature gradient, the heating output value, and time during stewing in a heating cooker according to a second embodiment. [Figure 6] FIG. 10 is a diagram showing the relationship between the temperature gradient, the heating output value, and time during stewing in a heating cooker according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0010] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims. (Embodiment 1) Hereinafter, the first embodiment will be described with reference to FIGS. [1-1.Configuration] In FIG. 1, the induction cooking appliance comprises a top plate 1 provided on the top surface of the appliance and a heating coil 3 constituting a heating means for inductively heating a cooking container 2 placed on the top plate 1 by generating a high-frequency magnetic field. The top plate 1 is made of an electrical insulator such as glass. The heating coil 3 is provided below the top plate 1. The heating coil 3 is divided into two concentric coils, an outer coil 3a and an inner coil 3b. A gap is provided between the outer coil 3a and the inner coil 3b. The cooking container 2 generates heat due to eddy currents generated by the high-frequency magnetic field of the heating coil 3.

[0011] An operation unit 13 is provided on the user side of the top plate 1 to allow the user to give instructions to start / stop heating, etc. A display unit (not shown) is also provided between the operation unit 13 and the cooking vessel 2.

[0012] The first temperature detection means 4, which is a temperature detection means constituted by a thermistor or the like, is provided at the center of the concentric circle between the outer coil 3a and the inner coil 3b, and the second temperature detection means 17 is provided between the outer coil 3a and the inner coil 3b. The installation locations of the first temperature detection means 4 and the second temperature detection means 17 are not particularly limited as long as they can detect the temperature of the heated object. The first temperature detection means 4 and the second temperature detection means 17 detect the temperature through the top plate 1. The first temperature detection means 4 and the second temperature detection means 17 may be sensors that detect infrared rays emitted from the object, such as photodiodes or thermopiles.

[0013] Below the heating coil 3, there are provided a rectifying and smoothing unit 6 that converts the AC voltage supplied from the commercial power supply 5 into a DC voltage, and an inverter circuit 7 that receives the DC voltage from the rectifying and smoothing unit 6 to generate a high-frequency current and output the generated high-frequency current to the heating coil 3. In addition, between the commercial power supply 5 and the rectifying and smoothing unit 6, there is provided an input current detection unit 8 that detects the input current flowing from the commercial power supply 5 to the rectifying and smoothing unit 6.

[0014] The rectifying and smoothing unit 6 has a full-wave rectifier 9 made up of bridge-connected diodes, and a low-pass filter made up of a choke coil 15 and a smoothing capacitor 16 connected between the output terminals of the full-wave rectifier 9. The inverter circuit 7 has a switching element 10 (an IGBT: Insulated Gate Bipolar Transistor in this embodiment), a diode 11 connected in anti-parallel to the switching element 10, and a resonant capacitor 12 connected in parallel to the heating coil 3. A high frequency current is generated by turning on / off the heating element 10. The inverter circuit 7 and the heating coil 3 constitute a high frequency inverter.

[0015] The induction heating cooker of this embodiment further has a control unit 14 that controls the on / off of the switching element 10 of the inverter circuit 7, thereby controlling the high-frequency current supplied from the inverter circuit 7 to the heating coil 3. The control unit 14 controls the on / off of the switching element 10 based on a signal transmitted from the operation unit 13 and the temperature detected by the first temperature detection means 4.

[0016] The control unit 14 includes a temperature control means 14a that controls the amount of heating power for the cooking vessel 2 by controlling the high-frequency current of the heating coil 3 based on the output of the first temperature detection means 4, and a temperature gradient calculation means 14b that calculates the amount of change over time in the detected value of the temperature detected by the first temperature detection means 4. These control operations are performed by a microcomputer (not shown).

[0017] The operation unit 13 is provided on the front side (user side) of the display unit. The operation unit 13 includes tactile switches 13a to 13d. The switches 13a to 13d are used to input cooking instructions and are provided corresponding to the heating units. Each of the switches 13a to 13d is assigned a specific function. For example, the switch 13a is an on / off switch assigned with the function of controlling the start and end of cooking. The switches are not limited to tactile switches, and may be touch switches such as capacitance detection switches.

[0018] The operation of the induction heating cooker of this embodiment configured as above will be described below. [1-2. Operation] The operation of the cooking device configured as above will be described below. First, the basic operating principle will be described using Fig. 2, and then the specific operation will be described using Figs. 3 and 4.

[0019] Fig. 2 is a diagram showing the relationship between time and the calculated temperature gradient value of the induction heating cooker in the first embodiment of the present invention, and is a plot of the temperature gradient Δθ when, for example, water is placed in cooking vessel 2 and heated. The temperature gradient curve shown by the solid line in Fig. 2 is found by outputting, for example, every second, the temperature difference of the detected temperature (in degrees Celsius) obtained by first temperature detection means 4 over 40 seconds.

[0020] After detecting the maximum value of the obtained temperature gradient Δθ (time T1), the heating output is reduced when the difference between this maximum temperature gradient and the temperature gradient reaches a predetermined value b (time T2), which is smaller than a predetermined value a, which is the temperature gradient difference at the boiling point. This ensures that the heating output is reduced before the water in the cooking vessel reaches a boiling point. Here, the predetermined value b corresponds to the first predetermined value, and the predetermined value a corresponds to the second predetermined value. Note that the timing for reducing the heating output is not limited to the point when the difference between the maximum temperature gradient and the temperature gradient reaches the predetermined value b, but may be within a time range where the difference is equal to or greater than the predetermined value b and less than the predetermined value a.

[0021] As described above, the present disclosure is characterized in that the heating output of the heating means is reduced based on the temperature gradient difference with respect to the maximum temperature gradient. The technical background and considerations that led to this feature are explained below. First, let us assume that the temperature detected by the temperature detection means is used as a condition for reducing the heating output of the heating means. In this case, when the detected temperature reaches a predetermined value, the total amount of heat applied to the pot may be excessive or insufficient due to factors such as the room temperature, the type of pot, and the temperature of the food being cooked at the start of heating. Therefore, if the heating output of the heating means is reduced based on the temperature detected by the temperature detection means itself, splashes and boiling over may occur if the total amount of heat is large, and the heating If the total amount is small, the cooking quality may be reduced.

[0022] To reduce the effects of such disturbances, this disclosure focuses on the temperature gradient, which is the relative difference in detected temperatures. By using the temperature gradient as a condition for reducing the heating output of the heating means, the difference in detected temperatures is used instead of the detected temperatures themselves, making it easier to control the total amount of heat generated by the pot, regardless of factors such as room temperature, the type of pot, and the temperature of the food at the start of heating, so that it is neither too high nor too low. As a result, splashes and overflows can be reduced, making it easier to maintain cooking quality.

[0023] Furthermore, the present disclosure is characterized in that the predetermined temperature gradient is the difference from the maximum temperature gradient. In this case, since the temperature gradient is the difference from the maximum temperature gradient, the predetermined temperature gradient value for reducing the heating output of the heating means can be set within as wide a numerical range as possible and can be set to as large a value as possible. This makes it easier to detect the pre-boiling state before the boiling state is reached. In the present disclosure, by setting the predetermined temperature gradient (first predetermined value, predetermined value b) to a value smaller than the difference from the maximum temperature gradient in the boiling state (second predetermined value, predetermined value a), the amount of heat from the heating means can be reliably reduced in the pre-boiling state before the boiling state is reached.

[0024] The inventors have arrived at the technical features of the present disclosure through the accumulation of the above-mentioned studies. Note that, although the explanation of the operating principle above has been given for the case of heating water contained in a cooking container, it is believed that a similar tendency will be observed in stewing dishes in which multiple ingredients are simmered in a cooking container, and therefore, an embodiment in which the present disclosure is actually applied to stewing dishes will be described below.

[0025] Hereinafter, the specific stewing operation of the induction heating cooker of this embodiment will be described based on a flowchart (FIG. 3) showing the control of stewing cooking of the heating cooker, and a characteristic diagram (FIG. 4) showing the relationship between the temperature gradient, heating output value, and time during stewing cooking.

[0026] First, the ingredients for stewing are placed in the cooking container 2, and the stewing start switch on the operation unit 13 is pressed to start heating. After temperature detection by the first temperature detection means 4 begins in step 1 (S1), the process proceeds to step 2 (S2), where the temperature detected in S1 is subtracted at predetermined detection time intervals (40 seconds) to calculate the temperature gradient Δθ. Next, in step 3 (S3), it is determined that the value of Δθ has reached its maximum value and that the maximum value is not being updated. If it is determined that the maximum value of Δθ continues to rise (N), the process returns to step S2, where the temperature gradient Δθ is calculated, and the above steps are repeated. If it is determined in S3 that time T1 has elapsed since the start of temperature detection as shown in FIG. 4 and the update of the maximum value has stopped (Y), the process proceeds to step 4 (S4), where it is determined whether the difference in temperature gradient from the maximum value in the temperature gradient difference Δθ is equal to or greater than a predetermined value b, which is a first predetermined value. If it is determined in S4 that time T2 has elapsed since the start of temperature detection as shown in FIG. 4 and the maximum temperature gradient difference has reached the predetermined value b (Y), the process proceeds to step 5 (S5).

[0027] In S5, the heating output is reduced according to the selected menu and timing is started, and heating continues until the predetermined time c is reached after moving to step 6 (S6). When the predetermined time c is reached (Y), the process moves to step 7 (S7) to confirm whether heating should be continued, and if not necessary (Y), heating is stopped. As a specific example, the following describes the cooking of Nikujaga (meat and potato stew) using a cooking pot 2 with a single layer of stainless steel and a 1.2 mm thick bottom. 600 g of potatoes, 150 g of carrots, 300 g of meat, 300 g of onions, and 300 g of konjac noodles are placed in the cooking pot 2 in this order, and heating begins after covering with a drop lid and a pot lid. The heating output for the first step is 1000 W, and the temperature difference Δθ is measured over 40 seconds.

[0028] In this example, the results of prior measurement showed that the maximum temperature gradient was 3.5°C, reaching the boiling point. The predetermined value a (second predetermined value) at that time was 3.0°C. Taking this into consideration, by presetting the predetermined value b (first predetermined value) to 2.0°C, the heating output can be reliably reduced to 370W before the boiling state is reached, and the process can proceed to the second step. In the second step, heating is continued at a heating output of 370W for the predetermined time c, 15 minutes.

[0029] Experiments were conducted on the above example, and it was confirmed that by satisfying these conditions, cooking was completed without boiling over and the meat and potato stew dish was completed. [1-3.Effects] As described above, in this embodiment, the cooking device comprises a heating means for heating a cooking container, a temperature detection means for directly or indirectly detecting the temperature of the cooking container, a temperature gradient calculation means for calculating a temperature gradient by subtracting the temperature detected over time by the temperature detection means at predetermined detection time intervals, and a control means for reducing the amount of heat generated by the heating means after the difference between the temperature gradient calculated by the temperature gradient calculation means and a maximum temperature gradient set as the maximum value becomes equal to or greater than a first predetermined value, but before the difference exceeds a second predetermined value, which is the difference between the temperature gradient in a boiling state and the maximum temperature gradient. This ensures that the heating output can be reduced before boiling is reached. This reduces the possibility of splashing or boiling over compared to boiling detection methods, which reduce the heating output when boiling is detected. Also, cooking is easy as the heating output only needs to be controlled in two stages. (Embodiment 2) [2-1. Configuration and Operation] First, a description will be given of a characteristic difference between embodiment 1 and embodiment 2. In embodiment 1, the second step following the first step is composed of a single heating step, whereas in embodiment 2, the second step includes multiple heating steps.

[0030] Next, we will explain the second embodiment in detail. Fig. 5 is a diagram showing the relationship between the calculated temperature gradient value and time of an induction heating cooker in the second embodiment of the present invention, and is a plot of the temperature gradient Δθ when, for example, water is placed in the cooking vessel 2 and heated. The temperature gradient can be found, for example, by outputting the temperature difference (in degrees Celsius) detected by the first temperature detection means 4 every second over 50 seconds.

[0031] This example shows the cooking of black soybeans using a cooking pot 2 with a single layer of stainless steel and a 1.2 mm thick bottom. 140 g of black beans, 100 g of sugar, 27 g of soy sauce, 800 g of water, 1 g of salt, and 1 g of baking soda are mixed into the cooking pot 2 and left at room temperature for 18 hours. The pot is then covered with a drop lid and the lid is then replaced and heating begins. The heating output for the first step is 1450 W, and the temperature difference Δθ is measured over 50 seconds.

[0032] In this example, preliminary measurements showed that the maximum temperature gradient was 2.1°C, and the predetermined value a (second predetermined value) at which the temperature reached a boil was 0.7°C. Taking this into consideration, the predetermined value b (first predetermined value) was set to 0.5°C in advance, which ensures that the heating output is reduced to 260 W before the temperature reaches a boil, and the process moves to the second step. In the second step, heating is continued at a heating output of 260 W for a predetermined time c until 90 minutes have elapsed. Thereafter, the heating output is reduced to 75 W, and heating is continued for a predetermined time d until 90 minutes have elapsed. Experiments were conducted on the above example, and it was confirmed that by satisfying these conditions, cooking was completed without overflow and the black bean stew was completed. [2-2. Effects] According to this embodiment, after the first step is switched to the second step, the heating output and cooking time are controlled in multiple stages in the second step, making it easy to set the heating output and cooking time according to the menu. Therefore, this is suitable for stewing, which requires a long time for the flavor to permeate the food. (Embodiment 3) [3-1. Configuration and Operation] FIG. 6 is a diagram showing the relationship between the calculated temperature gradient value and time of the induction heating cooker in the third embodiment of the present invention, and plots the temperature gradient Δθ obtained by the temperature gradient calculation means when heating is performed by dividing the first process into two stages of heating output (W1, W2).

[0033] When heating at a high heating output W1 in the first stage, the temperature of the food rises quickly, shortening the cooking time. However, because the temperature gradient Δθ becomes steeper, a sudden, large gradient in the transient temperature rise state is detected, and the desired threshold is exceeded earlier than expected, which may reduce the accuracy of pre-boiling detection.

[0034] Therefore, pre-boiling detection is performed in the second stage (W2) with a lower heating output than the first stage, but once the overshoot of the temperature gradient Δθ measured in the first stage has ended and the slope of the temperature gradient Δθ has stabilized, acquisition of the maximum temperature gradient value begins and the maximum temperature gradient is set, and the heating output is reduced when the difference between this temperature gradient and the maximum temperature gradient reaches a predetermined value b, as in embodiments 1 and 2. This ensures that the heating output can be reduced before the boiling state is reached while maintaining the accuracy of pre-boiling detection.

[0035] Here, the inclination of the temperature gradient Δθ becomes stable means that the temperature gradient becomes stable several seconds after the maximum temperature gradient begins to decrease after switching from a high heating output to a low heating output. [3-3. Effects] According to this embodiment, multiple heating processes each having a different heating output can be applied as the first process, and compared to a configuration using a single heating process consisting of one stage of heating output, the cooking time for the entire first process can be shortened while also shortening the time required for pre-boiling detection. (Other embodiments) The maximum temperature gradient in the present disclosure is not only the maximum value in the temperature gradient as described in embodiments 1 and 2, but may also be selected from a peak region including the vicinity of this maximum value, and further includes a case where it is selected from a gradient stability region where the variation in the temperature gradient decreases near the maximum value and the gradient stabilizes, as in embodiment 3. In this way, the maximum temperature gradient includes not only the maximum value in terms of numerical value but also the substantial maximum value in terms of technical significance. The numerical range of the maximum temperature gradient is preferably set in the range of more than 1°C and less than 50°C, taking into consideration the cooking menu, type of cooking pot, etc., and more preferably in the range of more than 2°C and less than 20°C. Even more preferably, the maximum temperature gradient is more than 2.1°C and less than 3.5°C, based on the examples described in the first and second embodiments.

[0036] This allows the maximum temperature gradient to be set as large as possible within the range applicable to practical cooking, which increases the degree of freedom in setting the predetermined value b, and also allows the predetermined value b to be set as large as possible. This makes it easier to detect the pre-boiling state before the boiling state is reached, and ensures that the amount of heat can be reduced before the boiling state is reached.

[0037] If the maximum temperature gradient is less than 2°C, and the temperature detection means has low detection accuracy, it may be difficult to detect the pre-boiling state before the boiling state is reached, and it may be difficult to reliably reduce the heating output before the boiling state is reached. On the other hand, if the maximum temperature gradient is greater than 20°C, the amount of temperature change per unit time becomes excessively large, making it difficult to apply to practical cooking.

[0038] The first predetermined value, the predetermined value b, in the present disclosure is not limited to the form (embodiments 1 and 2) in which it is set in advance based on the maximum temperature gradient and the predetermined value a measured in advance, but may also be set, for example, at the timing when the maximum temperature gradient is determined during actual measurement of the temperature gradient after stewing cooking has begun.

[0039] This predetermined value b is smaller than the second predetermined value, the predetermined value a, and is preferably set in the range of greater than 0°C and less than or equal to 9°C, taking into consideration the cooking menu, the type of cooking pot, etc., and more preferably in the range of greater than or equal to 0.5°C and less than or equal to 6.0°C. Even more preferably, the predetermined value b is greater than or equal to 0.5°C and less than or equal to 2.0°C, based on the examples described in the first and second embodiments. This makes it easier to detect the pre-boiling state before the boiling state is reached, and the amount of heat can be reliably reduced before the boiling state is reached.

[0040] The predetermined value a, which is the second predetermined value in the present disclosure, is preferably set in the range of greater than 0° C. and less than or equal to 9° C., taking into consideration the cooking menu, the type of cooking pot, etc., and more preferably in the range of greater than or equal to 0.5° C. and less than or equal to 6.0° C. Even more preferably, the predetermined value a is greater than or equal to 0.7° C. and less than or equal to 3.0° C., based on the examples described in the first and second embodiments.

[0041] The relationship between the above maximum temperature gradient, the predetermined value b, and the predetermined value a will now be explained. In order to reliably detect when the predetermined value b has been reached, the predetermined value b must be set to a required large value taking into consideration the detection accuracy of the temperature detection means. On the other hand, in order to reliably detect the pre-boiling state before the boiling state is reached, the predetermined value b must be smaller than the predetermined value a. Taking into consideration the detection accuracy of the detection means and the influence of external disturbances, it is desirable to set the predetermined value b to a value that has a predetermined difference from the predetermined value a.

[0042] From the above, it is considered desirable to set the predetermined value b within a range including the median (specifically, a / 2) between the temperature gradient corresponding to the predetermined value a and the maximum temperature gradient. In the first embodiment, the maximum temperature gradient is 3.5°C, the predetermined value b is 2.0°C, and the predetermined value a is 3.0°C, and the predetermined value b is set to a value 0.5°C larger than 1.5°C, which is the median (specifically, a / 2) between the temperature gradient corresponding to the predetermined value a and the maximum temperature gradient. In the second embodiment, the maximum temperature gradient is 2.1°C, the predetermined value b is 0.5°C, and the predetermined value a is 0.7°C, and the predetermined value b is set to a value 0.15°C larger than 0.35°C, which is the median (specifically, a / 2) between the temperature gradient corresponding to the predetermined value a and the maximum temperature gradient.

[0043] Therefore, when the predetermined value b and the predetermined value a satisfy the following formula 1, they satisfy both the first and second embodiments. Alternatively, the predetermined value b and the predetermined value a may have the upper and lower limits determined from the first and second embodiments, as in the following formula 2. b-(a / 2)≦|0.5℃| (Formula 1) 0.15℃≦b-(a / 2)≦0.5℃ (Formula 2) Furthermore, the difference (ab) between the specified value a and the specified value b may be determined using the values ​​obtained from embodiments 1 and 2 as the upper limit (3.0°C - 2.0°C = 1.0°C) and lower limit (0.7°C - 0.5°C = 0.2°C), respectively, as shown in Equation 3 below. 0.2℃≦(ab)≦1.0℃ (Formula 3) Furthermore, the ratio (b / a) of the predetermined value b to the predetermined value a is calculated as 2.0°C / 3.0°C and 0.5°C / 0.7°C in accordance with the first and second embodiments, respectively, which are 0.67 and 0.71. If the following formula 4 is satisfied, both the first and second embodiments are satisfied. (b / a)<0.72...(Equation 4) In addition, in the case of a cooking menu for which it is desired to raise the temperature of the food ingredients in the cooking container as quickly as possible, or in the case of accommodating a shortening of the cooking time, it may be considered to delay the timing of reducing the heating output. In this case, it is desirable that the difference between the predetermined value b and the predetermined value a is smaller than the difference between the temperature gradient corresponding to the predetermined value b and the maximum temperature gradient (specifically, the predetermined value b). That is, (a - b) < b, and the following formula 5 may be satisfied. (b / a) > 0.5 ··· (Formula 5) In addition, when splashing and spilling are likely to occur, it is desirable to appropriately set according to the cooking menu.

[0044] Furthermore, the detection time interval set by the temperature gradient Δθ obtained by outputting the temperature difference every 1 second for a certain period of time is preferably greater than 10 seconds and 100 seconds or less, for example, and more preferably set within the range of 30 seconds or more and 50 seconds or less. Even more preferably, the detection time interval is 40 seconds or more and 50 seconds or less based on the examples described in Embodiments 1 and 2. As a result, while being used for practical cooking, the degree of freedom in setting the predetermined value b increases as the maximum temperature gradient can be set as large as possible, and the predetermined value b can be set as large as possible. For this reason, it becomes easier to detect the pre-boiling state before reaching the boiling state.

[0045] Furthermore, regarding the timing of reducing the heating output of the heating means, in Embodiments 1 to 3, the difference in the temperature gradient with respect to the maximum temperature gradient was set when reaching the predetermined value b, but it is not limited to this, and the difference in the temperature gradient with respect to the maximum temperature gradient may be after reaching the predetermined value b and before reaching the predetermined value a.

[0046] Note that the above-described embodiments are for exemplifying the technology in the present disclosure, and various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or the equivalent scope thereof.

Industrial Applicability

[0047] The present disclosure is applicable to general heating cookers, such as electromagnetic induction cookers used in ordinary households for stewing, in which the heating output is reduced after boiling the liquid in the cooking container. [Explanation of symbols]

[0048] 1 top plate 2 Cooking containers 3 heating coils 4. First temperature detection means 5 Commercial power supply 6 Rectification and smoothing section 7 Inverter circuit 8 Input current detection section 9 Full wave rectifier 10 Switching element 11 Diode 12 Resonant Capacitor 13 Control section 14 Control Unit 14a Temperature control means 14b Temperature gradient calculation method 15 Choke coil 16 smoothing capacitor 17 Second temperature detection means

Claims

1. A cooking vessel for containing stewing ingredients; a heating means for heating the cooking vessel; a temperature detection means for directly or indirectly detecting the temperature of the cooking vessel; a temperature gradient calculation means for calculating a temperature gradient by subtracting the temperatures detected over time by the temperature detection means at predetermined detection time intervals; a control means for reducing the amount of heat from the heating means after a difference between the temperature gradient calculated by the temperature gradient calculation means and a maximum temperature gradient set as a maximum value becomes equal to or greater than a first predetermined value and before the difference exceeds a second predetermined value which is a difference between the temperature gradient in a boiling state and the maximum temperature gradient, The control means starts timing at the same time as reducing the amount of heat of the heating means, and continues heating until the predetermined time corresponding to the stewing ingredients has elapsed. A heating cooker characterized by:

2. 2. The cooking device according to claim 1, wherein, when the first predetermined value is b and the second predetermined value is a, b and a satisfy the following formula 1: b-(a / 2)≦|0.5℃|...(Formula 1)

3. 2. The cooking device according to claim 1, wherein, when the first predetermined value is b and the second predetermined value is a, b and a satisfy the following formula 2: 0.15℃≦b-(a / 2)≦0.5℃...(Formula 2)

4. 2. The cooking device according to claim 1, wherein, when the first predetermined value is b and the second predetermined value is a, b and a satisfy the following formula 3: 0.2℃≦(a-b)≦1.0℃...(Formula 3)

5. 2. The cooking device according to claim 1, wherein, when the first predetermined value is b and the second predetermined value is a, b and a satisfy the following formula 4: (b / a)<0.72...(Formula 4)

6. 2. The cooking device according to claim 1, wherein, when the first predetermined value is b and the second predetermined value is a, b and a satisfy the following formula 5: (b / a)>0.5...(Formula 5)

7. the maximum temperature gradient is 2.0°C or more and 20°C or less; the first predetermined value is equal to or greater than 0.5°C and equal to or less than 6.0°C; the second predetermined value is equal to or greater than 0.5°C and equal to or less than 6.0°C; the detection time interval is 30 seconds or more and 50 seconds or less, The first predetermined value is smaller than the second predetermined value. The cooking device according to claim 1.

8. the maximum temperature gradient is greater than or equal to 2.1°C and less than or equal to 3.5°C; the first predetermined value is equal to or greater than 0.5°C and equal to or less than 2.0°C; the second predetermined value is equal to or greater than 0.7°C and equal to or less than 3.0°C; the detection time interval is equal to or greater than 40 seconds and equal to or less than 50 seconds; The first predetermined value is smaller than the second predetermined value. The cooking device according to claim 1.

9. 2. The cooking device according to claim 1, wherein the maximum temperature gradient is a temperature gradient in a region where the inclination of the temperature gradient calculated by the temperature gradient calculation means is stable.

Images