rice cooker

Abstract

To provide a rice cooker that can cook rice using heating similar to that of a traditional Japanese hearth and that can reliably detect boiling. [Solution] The rice cooker comprises a pot for containing the food to be cooked, a pot sensor for detecting the temperature of the pot, a rice cooking control means for cooking the food by changing the heating amount of the side coils and bottom coils, and a heating amount fluctuation means for changing the heating amount of the side coils and bottom coils over time. The rice cooker includes a boiling heating step in which the temperature is raised until boiling of the food to be cooked is detected from the rate of temperature rise of the pot. In the boiling heating step, the heating amount fluctuation means changes the heating amount of the side coils and bottom coils so as to periodically repeat between an upper limit S2max of the heating amount, a lower limit S2min of the heating amount, and a heating amount between the upper limit S2max and the lower limit S2min until the pot reaches a predetermined temperature. In the boiling heating step, the rice cooking control means is configured not to execute the heating amount fluctuation means until boiling is detected.

Description

[Technical Field]

[0001] The present invention relates to a rice cooker that cooks rice by varying the heating amount of a heating means during heating of a pot. [Background Art]

[0002] When rice is cooked by burning firewood in a traditional cooking stove, the flame of the firewood fluctuates, and while subtly changing the heating power, it heats the bottom and side parts of the pot containing the rice to be cooked.

[0003] As a technique for approximating such traditional stove cooking, for example, Patent Document 1 discloses a rice cooker comprising: a bottom surface heating body (11) and a side surface heating body (12) that heat a pot (7); and a heating amount fluctuation means (44) that cooks rice on the rice to be cooked (A) by changing the heating amounts of the bottom surface heating body (11) and the side surface heating body (12) as the process progresses, wherein the heating amount fluctuation means (44) changes the heating amounts of the bottom surface heating body (11) and the side surface heating body (12) so as to periodically repeat an upper limit value of the heating amount, a lower limit value of the heating amount, and one or more heating amount values between the upper limit value and the lower limit value in the process. In the rice cooker of Patent Document 1, in the boiling heating step in which the temperature of the rice to be cooked (A) is raised to boiling in a short time and then the boiling state of the rice to be cooked (A) is maintained to achieve a dry-up state without water, boiling is detected when the temperature increase rate (e) of the pot bottom temperature (Tn) measured by a pot temperature sensor (15) becomes equal to or less than a predetermined value before the temperature reaches boiling. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent No. 7621781 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] In the rice cooker described in Patent Document 1, the amount of heat applied by the bottom heating element (11) and the side heating element (12) is changed even during the boiling heating process until the rice being cooked (A) boils. As a result, the temperature detected by the pot temperature sensor (15) follows the change in the amount of heat applied, which could negatively affect the determination of the boiling temperature.

[0006] Therefore, in view of the above circumstances, the present invention aims to provide a rice cooker that can cook rice using heating similar to that of a traditional Japanese hearth and that can reliably detect boiling. [Means for solving the problem]

[0007] The rice cooker of the present invention comprises a pot for containing the food to be cooked, a heating means for heating the pot, a detection means for detecting the temperature of the pot, a cooking control means for cooking the food by changing the amount of heating of the heating means as the process progresses, and a variable heating means for changing the amount of heating of the heating means over time, wherein the process is a boiling heating process in which the cooking control means raises the temperature of the pot until it detects boiling of the food to be cooked based on the rate of temperature rise of the pot. The process includes a soaking and cooking process performed before the boiling heating process to promote water absorption of the rice to be cooked, and a boiling continuation process performed after the boiling heating process to maintain the boiling state of the rice to be cooked. The variable heating means includes, in the boiling heating step, the upper limit of the heating amount and, until the pot reaches a predetermined temperature, One or more heating amount values ​​between the upper limit and the lower limit of heating amount, Lower limit and A cycle that gradually increases and decreases in order to take it in sequence. To reiterate, the heating amount of the heating means is changed, and in the boiling heating step, the rice cooking control means operates the heating amount variable means from the time the pot reaches a predetermined temperature until the rice cooking control means detects boiling. In the soaking and cooking process, the variable heating means changes the heating amount of the heating means so as to repeat a cycle of gradually increasing and decreasing the heating amount in a stepwise manner, taking an upper limit of the heating amount, one or more heating amount values ​​between the upper limit and the lower limit of the heating amount, and the lower limit. In the boiling continuation process, the rice cooking control means causes the variable heating means to execute. It is characterized by not having [something]. [Effects of the Invention]

[0008] According to the rice cooker of the present invention, rice can be cooked using heating similar to that of a traditional hearth, and boiling can be detected stably. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a rice cooker showing one embodiment of the present invention. [Figure 2]The same as above, this is a vertical cross-section of the rice cooker. [Figure 3] The above diagrams show a cross-sectional view of the inner frame and heating coil, and a plan view from the bottom side. [Figure 4] The same as above, this is a block diagram showing the electrical configuration of a rice cooker. [Figure 5] The graph above shows the time-dependent changes in the temperature of the bottom of the pot, the temperature of the inner lid, the measured temperature of the pot, the measured temperature of the food being cooked, and the heating amount of the heating coil. [Figure 6] Figure 5 shows an enlarged view of the boiling heating process and the boiling continuation process. [Figure 7] The graphs below show (A) the change over time in the amount of heat applied to the pot by the rice cooking control means and (B) the change over time in the amount of heat applied to the pot by the heat fluctuation means. [Figure 8] The graph above shows the change over time in the amount of heat applied to the pot by the heating amount fluctuation method. [Figure 9] The graph above shows the relationship between the amount of heat and the time spent heating over high heat. [Modes for carrying out the invention]

[0010] Hereinafter, preferred embodiments of the rice cooker according to the present invention will be described with reference to the attached drawings. Common reference numerals will be used for common parts throughout these drawings.

[0011] Figures 1 to 9 show an embodiment of the rice cooker according to the present invention. First, the overall configuration of the rice cooker will be described with reference to Figures 1 and 2. Reference numeral 1 denotes a main body, which has a substantially rectangular shape with opposed front and rear surfaces, and opposed left and right side surfaces when viewed from above, and has an open upper surface. Reference numeral 2 denotes a lid body that openably and closably covers the upper opening of the main body 1. Similarly to the main body 1, the lid body has a substantially rectangular shape with opposed front and rear surfaces, and opposed left and right side surfaces when viewed from above, and has a substantially flat upper surface. The main body 1 has a pot accommodating portion 3 with an open upper surface. When the lid 2 is opened, a bottomed pot 4 serving as a container for accommodating rice cooking objects such as water and rice is detachably accommodated in the pot accommodating portion 3. The pot accommodating portion 3 is formed by combining a bowl-shaped resin inner frame 5 and the like, and is entirely formed into a bottomed cylindrical shape.

[0012] The pot 4 is mainly made of aluminum 7 with good thermal conductivity, and a heating element 8 made of a magnetic metal plate such as ferritic stainless steel is joined from the lower side portion to the bottom portion of the outer surface of the main material 7. Further, a heating coil 11 is provided as a heating means for electromagnetic induction heating of the heating element 8 of the pot 4 on the outer surface of the inner frame 5 facing from the lower side portion of the pot 4 to the bottom surface. When a high-frequency current is supplied to the heating coil 11, the heating element 8 of the pot 4 generates heat by an alternating magnetic field generated from the heating coil 11, and the rice cooking object in the pot 4 is heated during rice cooking and heat insulation. The heating coil 11 will be described in detail later. Further, a pot sensor 12 serving as pot temperature detection means is disposed at the center of the bottom of the inner frame 5 so as to resiliently contact the outer bottom of the pot 4.

[0013] A hinge 13 serving as a connecting portion with the main body 1 is provided at a rear portion of the lid body 2. A lid operating body 14 is disposed in an exposed state on the front upper surface of the lid body 2. When the lid operating body 14 is pressed, the engagement between the main body 1 and the lid body 2 is released, and the lid body 2 is configured to open around the hinge shaft of the hinge 13 as a rotation center by a hinge spring 10 provided at the upper rear of the main body 1.

[0014] A steam port 15 for discharging steam generated from the rice to be cooked in the pot 4 to the outside of the rice cooker is disposed on the rear upper surface of the lid body 2. In addition to the steam port 15 and the lid operating body 14, the upper surface of the lid body 2 is provided with a display means 18 composed of an LCD (Liquid Crystal Display) 16 serving as a screen display unit and an LED (Light Emitting Diode) display unit 17 serving as a status display unit for displaying various information related to rice cooking, and an operating means 19 composed of a touch sensor disposed above the LCD 16 for starting rice cooking and allowing selection of time, rice cooking courses, etc., respectively. A control PC (Printed Circuit) board 21 provided with a control IC (not shown herein) for performing control related to operation and display is disposed on the lower surface of the display means 18 and the operating means 19.

[0015] The LED display unit 17 displays the actual status of the rice cooker. In this embodiment, the "reservation" LED display unit lights up when a reservation is set, the "heat insulation" process LED display unit lights up when the rice cooker enters a heat insulation state, the "vacuum" process LED display unit lights up when the inside of the pot 4 is brought into a depressurized state lower than the atmospheric pressure by a depressurizing means 38 to be described later, and the "pressure" process LED display unit lights up when the inside of the pot 4 is pressurized from the time pressure starts to be applied to the inside of the pot 4 during rice cooking until the rice to be cooked is cooked. Therefore, even in a dimmed state where the backlight of the LCD 16 is dimmed, the user can understand the current status of the rice cooker at a glance by checking the LED display unit 17.

[0016] The operating means 19 composed of a touch sensor is configured such that, for example, a plurality of components, in which a transparent electrode portion made of a conductive polymer and a contact portion connected to the control PC board 21 are connected by patterned wiring, are disposed as touch keys. When a touch operation is performed on any of the plurality of button display units displayed on the LCD 16, the touch key disposed above the corresponding button display unit and corresponding to the button display unit is touched, and the button display unit is selected.

[0017] An inner lid assembly 23, which serves as the lower component of the lid 2, is provided on the underside of the lid 2. The inner lid assembly 23 is made of a metal material and has a disc shape with approximately the same diameter as the upper opening of the pot 4. It comprises an inner lid 24 that covers the upper opening of the pot 4, a lid packing 25 which is an elastic member provided around the entire outer circumference of the inner lid 24 to seal the space between the inner lid 24 and the pot 4, and a pressure regulating unit 26 that adjusts the internal pressure of the pot 4. The annularly formed lid packing 25, as shown in Figure 2, contacts the upper surface of the pot 4, which is the opening, when the lid 2 is closed, sealing the gap between the pot 4 and the inner lid 24 and sealing in the steam generated from the pot 4.

[0018] Inside the lid 2, a lid opening / closing detection means 27 is provided near the hinge 13 to detect the opening and closing of the lid 2. The lid opening / closing detection means 27 can be of any detection type, such as optical, mechanical, or magnetic, as long as it can output a detection signal corresponding to the opening and closing of the lid 2. Inside the lid 2, a lid heater 31 is provided as a lid heating means for heating the inner lid 24, and a thermistor-type lid temperature sensor 32 is provided for controlling the temperature of the inner lid 24 using the lid heater 31. Inside the lid 2, a steam discharge path 33 is formed, connecting the steam vent 15 and the pressure regulating unit 26, as a passage for releasing steam generated in the pot 4 to the outside.

[0019] The pressure regulating unit 26 is equipped with a pressure regulating valve 34 that opens and closes the steam discharge path 33 between the inside of the pot 4 and the steam vent 15. The pressure regulating valve 34 is ball-shaped and works in conjunction with a solenoid 35 installed inside the lid 2. The solenoid 35 rotates the pressure regulating valve 34 so as to open the steam discharge path 33 when releasing steam from inside the pot 4 to the outside, and close the steam discharge path 33 when pressurizing or depressurizing the inside of the pot 4. When pressurizing, the food being cooked inside the pot 4 is heated by high-frequency current applied to the heating coil 11, causing the food to boil and generate steam. When this steam fills the inside of the pot 4 and the internal pressure of the pot 4 reaches a predetermined value, the pressure regulating valve 34 opens the steam discharge path 33 against its own weight, thereby maintaining the pressure inside the pot 4 at or above atmospheric pressure. A pressure sensor 36 (see Figure 4) is also installed inside the lid 2, facing the pressure regulating unit 26, to detect the pressure inside the pot 4.

[0020] 38 is a pressure reducing means for lowering the pressure inside the pot 4 to below normal atmospheric pressure when the lid 2 is closed on the main body 1. The pressure reducing means 38 reduces the internal pressure of the sealed pot 4 by energizing the solenoid 35 after the pot 4 is placed in the pot housing 3 and the lid 2 is closed, causing the pressure regulating valve 34 to block the steam discharge path 33. Furthermore, when the pressure inside the pot 4 falls below a certain value below atmospheric pressure, the operation of the pressure reducing pump 39, which is the operating source of the pressure reducing means 38, is stopped, and the inside of the pot 4 is kept in a reduced pressure state. In addition, when returning the inside of the pot 4 from a reduced pressure state to the same pressure as the outside air, the operation of the pressure reducing pump 39 is stopped, and a path (not shown) connecting the pressure reducing pump 39 and the inside of the pot 4 is opened. In other words, the pressure reducing means 38 also serves as a pressure return means for returning the inside of the pot 4 from a reduced pressure state to the same pressure as the outside air.

[0021] In addition, a unitized heating board assembly 42, including a control means 41, is arranged inside the main body 1. The control means 41 is configured to electrically control each part of the rice cooker and includes a control IC 43 that constitutes a microcomputer, a storage means 44 (see Figure 4) such as a memory that can read and write various information and data, and a timing means 45 (see Figure 4) such as a timer that can measure the time related to rice cooking. In particular, the control means 41 is configured to mainly control the heating coil 11 based on the temperature detected by the pot sensor 12 to manage the temperature of the bottom of the pot 4, and to mainly control the lid heater 31 based on the temperature detected by the lid temperature sensor 32 to manage the temperature of the inner lid 24 that faces the rice being cooked.

[0022] Figure 3 shows a cross-sectional view and a plan view of the inner frame 5 and heating coil 11 as seen from the bottom side. Referring to this figure, the heating coil 11 in this embodiment is composed of a side coil 11-1 as the first coil and a bottom coil 11-2 as the second coil. The side coil 11-1 and the bottom coil 11-2 are each provided on the outer surface of the inner frame 5, that is, the outer surface of the pot storage section 3, so as to face the pot 4. Specifically, when the pot 4 is placed in the pot storage section 3, the bottom coil 11-2 is positioned as a bottom heater facing the outer surface of the bottom of the pot 4, and the side coil 11-1 is positioned as a side-bottom heater outside and above the bottom coil 11-2, facing the outer surface of the lower side of the pot 4. In this embodiment, the heating coil 11 is composed of two heating coils, but the present invention is not limited thereto, and may be composed of many more heating coils. In that case as well, each heating coil is arranged concentrically facing the lower side of the pot 4 from the bottom, and multiple heating coils are arranged in a vertical direction. Furthermore, the side coil 11-1 and the bottom coil 11-2 may each be individually formed in a helical shape or in a concentric circular shape, and there are no particular restrictions on the shape of each heating coil.

[0023] To explain the heat transfer when the heating coil 11 is driven, when the side coil 11-1 is energized, the outer surface of the lower side of the pot 4, which is opposite the side coil 11-1, becomes hot first, and this heat is transferred via the main material 7 to the water in the cooked food that is in contact with the lower side. Heat transfer in the cooked food mainly occurs together with the movement of water, but where there is rice in the cooked food, the movement of water is restricted to only the narrow gaps between the rice grains of the cooked food S, and the movement of water and heat slows down. On the other hand, where there is no rice, the movement of water and heat becomes active due to convection, so after the water in the cooked food that is in contact with the lower side, the water in the upper part of the cooked food where there is no rice because it sinks downwards becomes hot. Subsequently, in the central part of the cooked food, the water and heat from the upper part of the cooked food, which has become hot, move to the middle part of the cooked food, which is a low temperature part, and then move to the lower part of the cooked food. This phenomenon is known as thermal convection, and in this embodiment, it will be described as external convection.

[0024] When the bottom coil 11-2 is energized, the outer surface of the bottom of the pot 4, which is opposite the bottom coil 11-2, becomes hot first, and this heat is transferred via the main material 7 to the water in the cooked food that is in contact with the bottom. In the lower part of the cooked food, the rice has settled downwards, so the upper part of the lower part is covered with the rice and water, and the temperature and pressure of this water rise. Subsequently, the water in the lower part, which has become hotter and more pressured, moves upward through the gaps between the rice grains, and is blown upward, causing the water in the lower part, i.e., the hot water, to move with the heat to the middle part of the cooked food, and then to the upper part. This phenomenon is called blowing up, and in this embodiment, it is described as internal convection.

[0025] Therefore, by alternately energizing the side coil 11-1 and the bottom coil 11-2, alternating external and internal heat convection occurs in the food being cooked in the pot 4. This promotes stirring of the water in the food being cooked in the pot 4, thereby reducing uneven heating.

[0026] Figure 4 shows the electrical configuration of the rice cooker in this embodiment. In the figure, the control means 41 equipped on the main body 2 receives operation signals from the operation means 19, temperature detection signals from the pot sensor 12 and lid temperature sensor 32, pressure detection signals from the pressure sensor 36, and detection signals from the lid opening / closing detection means 27, and sends control signals to the side coil drive means 46, bottom coil drive means 47, and lid heater drive means 48 during cooking and warming, respectively, to control the heating coil 11 that heats the pot 4 and the lid heater 31 that heats the inner lid 24, respectively. It also controls the solenoid 35 that moves the aforementioned pressure regulating valve 34 and the operation of the pressure reducing pump 39 of the pressure reducing means 38, respectively.

[0027] The side coil driving means 46 receives a heating control signal from the control means 41 and supplies a high-frequency current to energize the side coil 11-1, while the bottom coil driving means 47 receives a heating control signal from the control means 41 and supplies a high-frequency current to energize the bottom coil 11-2. These side coil driving means 46 and bottom coil driving means 47 are configured to include, for example, a power supply circuit, an inverter, an IH drive circuit, and a switching element such as an IGBT.

[0028] The power supply circuit corresponds to a rectifier and smoothing circuit that converts, for example, a 100V AC commercial power supply voltage supplied to the main unit 1 into a DC voltage, and the DC voltage from the power supply circuit is applied to the inverter as the input voltage. The inverters are not shown in the figures, but they are well-known voltage-type resonant inverters equipped with a resonant capacitor that forms a resonant circuit by being connected in parallel with the side coil 11-1 and the bottom coil 11-2, and the aforementioned switch element connected in series with the resonant circuit. The IH drive circuit receives a control signal from the control means 41 and sends a pulse drive signal sufficient to turn the aforementioned switch element on and off to the gate of the switch element. As a result, when a pulse drive signal is applied from the IH drive circuit to the gate of the switch element, the emitter-collector of the switch element repeatedly turns on and off, and the power supply voltage from the power supply circuit is intermittently applied to the resonant circuit of the inverter, and a high-frequency current is supplied to the side coil 11-1 and the bottom coil 11-2. At this time, by changing the period of the pulse drive signal and the ratio of the on-time to one period (on-time ratio), the output power from the inverter (output) and, consequently, the amount of heat transferred from the side coil 11-1 and bottom coil 11-2 to the pot 4 can be increased or decreased.

[0029] Furthermore, the lid heater driving means 48 receives a heating control signal from the control means 41 and drives the lid heater 31 by supplying a DC current or AC current to it. In this embodiment, the energization of the side coil 11-1 and the bottom coil 11-2 is described as being selectively switched by an element such as a relay, but the present invention is not limited to this, and may include a period in which the side coil 11-1 and the bottom coil 11-2 are energized simultaneously.

[0030] The control means 41 is equipped with a control IC 43 that includes a rice cooking control means 51, a heat retention control means 52, a display control means 53, and a heating amount fluctuation means 54 as functions on the control sequence of the program read from the storage means 48. The rice cooking control means 51 receives an instruction from the operation means 19 to start rice cooking and performs rice cooking control by sequentially executing the following steps: a soaking cooking step to raise the temperature of the rice to be cooked in the pot 4 to a temperature that does not gelatinize the rice, for example, 35 to 55°C, and a maximum of 60°C, to promote water absorption of the rice; a boiling heating step to raise the temperature of the rice to be cooked to a boil in a short time in order to gelatinize the rice; a boiling continuation step to maintain the boiling state of the rice to be cooked; and a steaming step to maintain a high temperature that does not burn the rice, thereby cooking the rice to be cooked at a desired pressure. The heat retention control means 52 controls the rice inside the pot 4 to maintain a predetermined heat retention temperature. The display control means 53 generates various control signals based on the operation signals from the operation means 19 and controls the display operation of the display means 18.

[0031] The heating amount fluctuation means 54 generates a second pattern different from the first pattern as needed when the rice cooking control means 51 operates the side coils 11-1, bottom coils 11-2, and lid heater 31 to heat the pot 4 according to a first pattern corresponding to the selected rice cooking course, and based on this second pattern, it changes the amount of heat transferred from the side coils 11-1, bottom coils 11-2, and lid heater 31 to the food being cooked in the pot 4 over time. The details of this heating amount fluctuation means 54 will be explained in more detail later.

[0032] The memory means 44 stores, for example, rice cooking courses corresponding to the settings for each type of rice, the cooking method, and the hardness setting. The display control means 53 controls the display means 18 to display the rice settings, cooking method, and hardness settings of the rice cooking courses stored in the memory means 44 in a selectable format. By selecting these settings with the operation means 19, the user selects and sets the rice cooking course. During the rice cooking process, the amount of rice to be cooked is determined by determining the volume of the rice to be cooked in the pot 4.

[0033] Furthermore, the memory means 44 stores multiple heating patterns, which are the driving patterns of the heating coil 11, lid heater 31, pressure regulating valve 34, and pressure reducing means 38, specifying the timing and output at which the heating coil 11, lid heater 31, pressure regulating valve 34, and pressure reducing means 38 are driven, as well as multiple energizing patterns, which are the energizing patterns of the side coil 11-1 and bottom coil 11-2, specifying the timing and output at which the side coil 11-1 and bottom coil 11-2 are energized when the heating coil 11 is driven. The rice cooking control means 51 and the warming control means 52 control the heating coil 11, lid heater 31, pressure regulating valve 34, and pressure reducing means 38 based on these heating patterns and energizing patterns.

[0034] In this embodiment, the storage means 44 has a plurality of specific second patterns that enable the heating amount fluctuation control by the heating amount fluctuation means 54 for various types of rice cooking performed by the rice cooking control means 51. The heating amount fluctuation means 54 selects and applies one of the plurality of second patterns according to the type of rice cooking. Thus, the heating amount fluctuation means 54 in this embodiment is configured to have a plurality of second patterns depending on the type of rice cooking performed by the rice cooking control means 51. Therefore, in this embodiment, a second pattern that enables appropriate heating amount fluctuation control is selected according to the amount of rice to be cooked, the cooking menu, the cooking method, and the origin, variety, and brand of rice.

[0035] In this embodiment, for all cooking courses that can be heated by the rice cooker, a first pattern is pre-stored in the storage means 44, which specifies how the display means 18, heating coil 11, and lid heater 31 should operate as each cooking process progresses from soaking to steaming, and how this will change the amount of heat transferred from the heating coil 11 and lid heater 31 to the food being cooked in the pot 4. After the user selects any cooking course from among multiple cooking courses by operating the operation means 19, and is instructed to start cooking, the cooking control means 51 and the display control means read the first and second patterns corresponding to the selected cooking course from the storage means 44. By appropriately controlling the side coil 11-1, bottom coil 11-2, and lid heater 31 in addition to the display means 18, the cooking operation is performed on the food being cooked in the pot 4 while the display means 18 displays the information.

[0036] Next, the operation of the rice cooker with the above configuration during the rice cooking process will be explained. Figure 5 shows graphs of the time-dependent changes in the pot bottom temperature Tn, which corresponds to the temperature of the bottom of the pot 4 detected by the pot sensor 12, the lid temperature Tf, which corresponds to the temperature of the inner lid 24 detected by the lid temperature sensor 32, the measured temperature Tp of the pot 4, the measured temperature Ts of the food being cooked, and the heating amount S of the heating coil 11 in the rice cooker of this embodiment. Figure 6 shows a graph extracted from Figure 5, showing the boiling heating process and the boiling continuation process. To make the graphs easier to understand, the values ​​of the NTC thermistors used in the pot sensor 12 and lid temperature sensor 32 are used directly for the pot bottom temperature Tn and lid temperature Tf, and the graphs for the pot bottom temperature Tn and lid temperature Tf show that the detected values ​​decrease as the temperature rises.

[0037] First, to explain the operation in the rice cooking process of this embodiment, rice and water (as liquid) are placed in the pot 4, and after setting the pot 4 in the pot storage section 3, the lid 2 is closed. Around the same time, when the rice cooker is powered on, the main body 1 and lid 2 enter an initial off (standby) state in which cooking and warming are not taking place.

[0038] Then, when the cooking course is set using the operation means 19 and cooking is started, the cooking control means 51 of the control means 41 performs the following cooking operations on the food to be cooked in the pot 4: soaking, boiling, boiling, and steaming, according to the heating pattern of the current cooking course setting stored in the memory means 44.

[0039] When the soaking process begins, the process transitions to a no-heat soaking process, and the rice cooking control means 51 controls the operation of the pressure regulating unit 26 and the pressure reducing means 38 so that the pressure inside the pot 4 is reduced to a state lower than atmospheric pressure. Specifically, when the no-heat soaking process begins, the rice cooking control means 51 controls the solenoid 35 to close the steam discharge path 33 with the pressure regulating valve 34. In this state, based on the pressure detection by the pressure sensor 36, the rice cooking control means 51 opens the path of the pressure reducing means 38 and operates the vacuum pump 39 continuously to perform vacuuming, removing the air from inside the sealed pot 4 with the vacuum pump 39. The display control means 53 also controls the LED display unit 17 to light up the "vacuum" process LED display unit. Subsequently, the rice cooking control means 51 controls the pressure reducing means 38 so that the pressure inside the pot 4 is maintained below a certain value in a reduced pressure state lower than atmospheric pressure. In this way, the inside of the pot 4 is kept in a reduced pressure state. Time of the non-heated soaking process T A This setting changes depending on the rice settings, hardness settings, and cooking method settings, but it does not change depending on the amount of food being cooked or the water hardness settings, and is configured to reach a predetermined value. Therefore, for a predetermined time T A This allows the rice to absorb water in a reduced pressure state inside the pot 4 with room temperature water, ensuring that water is absorbed all the way to the inside of the rice grains, regardless of the amount of rice being cooked or the water hardness setting.

[0040] The rice cooking control means 51 receives time T from the timing means 45 after the start of the non-heated soaking process. A Upon receiving the elapsed time signal, the process proceeds to the heating and soaking stage.

[0041] When the heating and soaking process begins, the rice cooking control means 51 controls the solenoid 35 to rotate the pressure regulating valve 34 to open the steam discharge path 33, thereby connecting the inside of the pot 4 to the outside of the main unit 1, and releasing steam from the rice being cooked through the steam discharge path 33 to the outside of the main unit 1 through the steam outlet 15. By fluctuating the pressure inside the pot 4 in this way, air that was inside the rice being cooked is expelled from the rice, and water is allowed to permeate in place of the expelled air, so that water can be absorbed into the inside of the rice.

[0042] Furthermore, when the heating and soaking process begins, the rice cooking control means 51 outputs a heating control signal to the side coil driving means 46, controlling the side coil 11-1 to heat the pot 4 at a predetermined output for a predetermined time T1. After time T1 has elapsed, the rice cooking control means 51 controls the side coil 11-1 to stop heating the pot 4 for a predetermined time T2, and performs a capacity determination process to determine the cooking capacity, which is the amount of rice to be cooked, based on the pot temperature t1 after time T2 has elapsed. The predetermined time T2 is set to a time that allows for a temperature drop sufficient to enable capacity determination from the time T1 when heating stops. In this embodiment, in the capacity determination process, the bottom coil 11-2, which is the heating coil 11 closest to the pot sensor 12, is not used, and only the side coil 11-1, which is the heating coil 11 furthest from the pot sensor 12, is used to heat the pot 4. Therefore, the pot sensor 12 is suppressed from being affected by the heating of the heating coils 11, and the deterioration of the temperature detection accuracy of the pot sensor 12 can be suppressed.

[0043] Furthermore, during the heating and soaking process, when the rice cooking control means 51 receives a detection signal from the pot sensor indicating that the pot temperature t1 has reached 60°C during the heating time T1 of the pot 4, the rice cooking control means 51 stops heating the pot 4 at the time of receiving the detection signal, and then controls the side coil 11-1 to stop heating the pot 4 for a predetermined time T2. If the rice and water to be cooked reach temperatures of 60°C or higher, it can accelerate the gelatinization of the rice during water absorption, potentially resulting in poorly cooked rice. Therefore, in the capacity determination process, the pot temperature t1 is kept below 60°C to suppress the gelatinization of the rice during water absorption.

[0044] On the other hand, the heating amount fluctuation means 54, which is the main focus of the invention in this embodiment, increases or decreases the amount of heat applied to the pot 4 by induction heating every 1 second to 120 seconds within a period of 1 second to 120 seconds, in response to the change in the amount of heat applied to the pot 4 over time by the rice cooking control means 51, and generates a second pattern in which the output of the inverter of the side coil driving means 46, which corresponds to the amount of heat applied to the side coil 11-1, changes to approximately 200W overall. Then, a heating configuration that simulates the fluctuation of a wood-burning flame is added so that the amount of heat applied to the pot 4 from the side coil 11-1 is based on this second pattern.

[0045] In other words, as shown in Figure 7(A), the conventional rice cooking control means 51 changes the amount of heat S1 to the pot 4 as the process progresses, and the heating amount fluctuation means 54 adds a fluctuation change in the amount of heat S2 to the pot 4, as shown in Figure 7(B). The heating amount fluctuation means 54 sets the output maintenance time D, in which the output of the inverters of the side coil drive means 46 and the bottom coil drive means 47 is kept constant within a cycle (period) C of 1 to 10 seconds, to a range of 0.1 seconds to 1 second, and gradually increases or decreases the output of the inverters for each of these output maintenance times D, generating a second pattern in which the output change amount E, which is the difference between the upper and lower limits of the inverter output, changes to about 200W, and in this second pattern, the side coils 11-1 provide a fluctuation change in the amount of heat S2 to the pot 4. As a result, the final amount of heat S to the pot 4 shown in Figures 5 and 6 is the sum of the amount of heat S1, which is changed by the rice cooking control means 51, and the amount of heat S2, which is changed in a fluctuating manner by the heat amount fluctuation means 54.

[0046] Figure 7(B) shows three typical examples of fluctuations in the heating amount S2 applied to the pot 4. However, the heating amount S2 and its fluctuation patterns produced by the heating amount fluctuation means 54 are not limited to those shown in this embodiment.

[0047] The heating amount fluctuation means 54, as an example of achieving a low flame and gentle heat during the "boiling heating" process, sets the inverter output from 300W (lower limit) → 440W → 580W → 620W → 660W → 700W (upper limit) → 660W → 620W → 580W → 440W → 300W (lower limit) as one cycle C. Sets one cycle C for a gentle flame to 7 seconds, and sets the output maintenance time D to 1 second to keep each output constant, thereby repeatedly supplying the pot 4 from the side coil 11-1 with a heating amount S2 change cycle in which the inverter output varies every 1 second.

[0048] When the rice cooking control means 51 receives a timing signal from the timing means 45 indicating that time T2 has elapsed, it outputs heating control signals to the side coil driving means 46 and the bottom coil driving means 47, respectively, based on the temperature detection of the bottom of the pot 4 by the pot temperature sensor 12. This controls the side coil 11-1 and the bottom coil 11-2 to be energized alternately, heating the pot 4 and raising the water temperature inside the pot 4 to a predetermined temperature, for example, 35-55°C, or a maximum of 60°C, as shown in Figure 5, to promote water absorption by the rice. In this embodiment, the rice cooking control means 51 is configured to drive from the uppermost heating coil 11 during the boiling heating process, and in this embodiment, it is configured to drive from the side coil 11-1. Therefore, the temperature of the rice being cooked can be raised from the upper part of the pot 4, and the temperature of the rice being cooked can be raised in a curve similar to that of heating the pot 4 in a traditional Japanese stove. In this embodiment, the rice cooking control means 51 provides a time during the boiling heating process when the heating coil 11, which is driven to output rated power, is heated to its maximum capacity. After the output of rated power, the heating coil 11 is controlled to gradually decrease the heating capacity. For example, in this case, the heating coil 11 is controlled so that the heating capacity of the side coil 11-1 is greater than that of the bottom coil 11-2, allowing the temperature of the rice to be cooked, located at the top of the pot 4, to rise from there, and enabling the temperature of the rice to be cooked to rise in a curve similar to that of heating the pot 4 in a traditional Japanese stove.

[0049] Furthermore, the heating amount fluctuation means 54 repeatedly applies the aforementioned cycle of changing heating amount S2, which enables a gentle flame with low heat, to the pot 4 from the side coil 11-1 and bottom coil 11-2, which are the heating coils 11 currently in operation. The heating amount S2, which changes in a fluctuating manner by the heating amount fluctuation means 54, is added to the heating amount S1, which is changed by the rice cooking control means 51.

[0050] Subsequently, when the rice cooking control means 51 receives a timing signal from the timing means 45 indicating that a predetermined time has elapsed for the heating and soaking process from the start of the heating and soaking process, it terminates the soaking and cooking process and moves on to the next boiling and heating process.

[0051] When the process transitions to the boiling heating stage, the rice cooking control means 51 stops the operation of the pressure reducing pump 39 of the pressure reducing means 38 and controls the path of the pressure reducing means 28 to be closed so that the inside of the pot 4 remains in a reduced pressure state lower than atmospheric pressure, continuing from the soaking cooking stage. Therefore, even after transitioning from the soaking cooking stage to the boiling heating stage, although the pressure inside the pot 4 gradually increases due to heating and slow leaks, the reduced pressure state can be maintained for a while without operating the pressure reducing pump 39. In this way, the contents being cooked inside the pot 4 are kept in a reduced pressure state even during the boiling heating stage after the soaking cooking stage, so that the water boils at a temperature of 100°C or less during the boiling heating stage. Therefore, by boiling the contents being cooked in a reduced pressure state at 60°C to 100°C, which is considered the gelatinization temperature of rice, the bubbles during boiling cause the rice to swirl, eliminating uneven heating, and the reduced pressure state of the contents allows the rice to absorb water to the core in a short time.

[0052] When the process moves to the boiling heating stage, the rice cooking control means 51 outputs heating control signals to the side coil driving means 46 and the bottom coil driving means 47, respectively, to alternately energize the side coil 11-1 and the bottom coil 11-2 so that the rice to be cooked in the pot 4 is heated more strongly than in the soaking cooking stage, and the process continues until boiling of the rice is detected.

[0053] The heating amount fluctuation means 54, in order to achieve a strong flame and intense heat during the "boiling" process up to boiling, sets the inverter output to 1200W (lower limit) → 1240W → 1280W → 1320W → 1360W → 1400W (upper limit) → 1360W → 1320W → 1280W → 1240W → 1200W (lower limit) as one cycle C. The intense flame is set to have a minimum cycle C of 1 second, and the output maintenance time D, during which each output is kept constant, is set to a minimum of 0.1 seconds. This configuration repeatedly applies a heating amount S2 change cycle to the pot 4 from the side coil 11-1 and bottom coil 11-2, such that the inverter output is varied in steps every 0.1 seconds.

[0054] The rice cooking control means 51 receives a temperature detection signal from the pot temperature sensor 14, and when the detected temperature at the bottom of the pot 4 reaches a predetermined temperature, such as 70°C, it controls the solenoid 35 to rotate the pressure regulating valve 34 to open the steam discharge path 33, without operating the pressure reducing pump 39, thereby connecting the inside of the pot 4 to the outside of the main unit 1, and releasing steam from the food being cooked through the steam discharge path 33 to the outside of the main unit 1 through the steam vent 15. The display control means 53 then controls the LED display unit 17 to turn off the "vacuum" process LED display unit.

[0055] Subsequently, the rice cooking control means 51 receives a temperature detection signal from the pot sensor 12 indicating that the pot temperature has reached a predetermined temperature or higher, for example, 80°C or higher, and / or receives a temperature detection signal from the lid temperature sensor 32 indicating that the lid temperature has reached a predetermined temperature or higher, for example, 73°C or higher. Upon receiving this signal, it determines that the boiling detection period has begun, which is the period until the boiling of the cooked rice is detected, and starts boiling detection to detect the boiling of the cooked rice.

[0056] When boiling detection is initiated, the rice cooking control means 51 prevents the heating amount fluctuation means 54 from operating during the boiling detection period, and stops providing the heating amount S2 change cycle to the side coils 11-1 and bottom coils 11-2, which are the driven heating coils 11, thereby suppressing the temperature detected by the pot sensor 12 from following the change in heating amount S2 and suppressing its influence on the determination of the temperature rise rate of the pot 4. The display control means 53 then controls the LED display unit 17 to light up the "pressure" process LED display unit. The rice cooking control means 51 may also control the solenoid 35 to adjust the pressure inside the pot 4 based on the pressure detected by the pressure sensor 36, for example, depending on the setting of the type of rice.

[0057] The rice cooking control means 51 also calculates the slope of the detected temperature, i.e., the temperature rise rate (e), which is how much the temperature detected by the pot sensor 12 and the temperature detected by the lid temperature sensor 32 rise in a predetermined time. Specifically, if the rice cooking control means 51 calculates from the temperature detected by the pot sensor 12 that the rise in the pot temperature, which is the temperature at the bottom of the pot 4, has fallen below a predetermined temperature rise rate, for example, 3°C or less in 120 seconds, it determines that boiling has been detected due to a change in the temperature rise rate of the pot temperature. Similarly, if the rice cooking control means 51 calculates from the temperature detected by the lid temperature sensor 32 that the rise in the lid temperature, which is the temperature of the inner lid 24, has fallen below a predetermined temperature rise rate (f), for example, 1°C or less in 60 seconds, it determines that boiling has been detected due to a change in the temperature rise rate of the lid temperature. The rice cooking control means 51 then determines that boiling has been detected in the cooked rice when it detects boiling due to a change in the rate of temperature rise of the pot temperature or due to a change in the rate of temperature rise of the lid temperature, or when it detects boiling due to a change in the rate of temperature rise of the pot temperature and boiling due to a change in the rate of temperature rise of the lid temperature, and proceeds to the next boiling continuation step. The predetermined rate of temperature rise of the pot temperature (e) and the predetermined rate of temperature rise of the lid temperature (f) for detecting boiling may be adjusted and set according to the amount of cooked rice determined in the capacity determination step. Furthermore, the boiling detection method is just one example, and the rice cooking control means 51 may be configured to proceed to the next boiling continuation step when it determines that boiling has been detected due to a change in the rate of temperature rise of the pot temperature.

[0058] When the process moves to the boiling continuation stage, the rice cooking control means 51 controls the lid heater 33 to continuously supply power to the lid heater 33 so that the lid temperature is maintained at a predetermined temperature, such as 98°C or higher, based on the temperature detected by the lid temperature sensor 32. At the same time, it controls the heating coil 11 to maintain the pot temperature at a predetermined temperature based on the temperature detection signal from the pot sensor 12. Here, the rice cooking control means 51 reduces the heating amount of the side coil 11-1 and the bottom coil 11-2, controlling the side coil drive means 46 and the bottom coil drive means 47 to continuously heat the pot 4 at a low output. This configuration allows the side coil 11-1 and the bottom coil 11-2 to be driven without interruption after the rice to be cooked has come to a full boil, thereby continuously supplying heat and maintaining boiling. In this case, the rice cooking control means 51 may be configured to reduce the heating amount of the side coil 11-1 and the bottom coil 11-2 in accordance with the rice cooking capacity determined in the capacity determination step. For example, if it is determined that the amount of rice to be cooked in the pot 4 is a small amount such as 1 go, the rice cooking control means 51 controls the heating amount of the side coil 11-1 and the bottom coil 11-2 to a level that allows the pot 4 to be continuously heated even with such a small amount of rice. Alternatively, if it is determined that the amount is a large amount such as 5 go, the rice cooking control means 51 may control the reduction in heating amount to a level that allows the pot 4 to be continuously heated even with such a large amount of rice.

[0059] Here, the rice cooking control means 51 prevents the heating amount fluctuation means 54 from continuing to operate even when the boiling continuation process is initiated, and stops the application of the heating amount S2 change cycle to the side coil 11-1 and bottom coil 11-2, which are the driven heating coils 11. This suppresses the temperature detected by the pot sensor 12 from following the change in heating amount S2, and ensures that the pot temperature is stably maintained at a predetermined temperature.

[0060] Furthermore, once the boiling process begins, the rice cooking control means 51 periodically controls the power supply of the solenoid 35 to repeatedly change the pressure inside the pot 4 between normal pressure and a pressure higher than atmospheric pressure, thereby periodically opening and closing the steam discharge path 33 with the pressure regulating valve 34.

[0061] The rice cooking control means 51 starts detecting when the rice is cooked when the water inside the pot 4 begins to disappear during the boiling process, and the temperature at the bottom of the pot 4 reaches a predetermined temperature or higher based on the temperature detected by the pot temperature sensor 15, or when the temperature rise reaches a predetermined temperature or higher relative to the pot sensor temperature at which boiling was detected.

[0062] When the detection of the end of cooking is initiated, the rice cooking control means 51 controls the solenoid 35 to close the steam discharge path 33 with the pressure regulating valve 34. The rice cooking control means 51 also outputs heating control signals to the side coil driving means 46 and the bottom coil driving means 47, respectively, to increase the energizing time Q seconds of the bottom coil 11-2 in one cycle from the energizing time O seconds of the bottom coil 11-2 in one cycle before the detection of the end of cooking in the boiling continuation process (Q>O), while setting the energizing time R seconds of the side coil 11-1 in one cycle to be less than or equal to the energizing time P seconds of the side coil 11-1 in one cycle before the detection of the end of cooking in the boiling continuation process (R≦P), and controls the side coil 11-1 and the bottom coil 11-2 with an energizing pattern that alternates between energizing them so that the food being cooked in the pot 4 is heated more strongly than before the detection of the end of cooking. Therefore, in the cooking process, the energizing time Q seconds for the bottom coil 11-2 in one cycle is set to be longer than the energizing time R seconds for the side coil 11-1. When the cooking is complete, there is almost no water left in the pot 4, and no internal or external convection occurs. By making the energizing time of the bottom coil 11-2 longer than that of the side coil 11-1, the water remaining at the bottom of the pot 4 can be heated more efficiently from the bottom side.

[0063] The rice cooking control means 51 receives a temperature detection signal from the pot sensor 12 indicating that the pot temperature has reached a predetermined dry-up temperature, for example, 120°C, or calculates from the temperature detection signal from the pot sensor 12 that the rise in pot temperature has exceeded a predetermined temperature rise relative to the boiling temperature detected by the pot sensor. Upon receiving this signal, the means 51 determines that the water inside the pot 4 has evaporated and the rice to be cooked is complete, and proceeds to the next steaming step.

[0064] During the steaming process, the rice cooking control means 51 controls the lid heater 33 to continuously supply power to the lid heater 33 based on the temperature detected by the lid temperature sensor 32 so that the lid temperature maintains a predetermined temperature, thereby preventing condensation on the inner lid 24. At the same time, it controls the power supply to the heating coil 11 for a predetermined time to maintain a high temperature so that the rice inside the pot 4 does not burn, thereby managing the temperature at the bottom of the pot 4. Here, even when the process moves to the boiling continuation stage, the rice cooking control means 51 prevents the heating amount fluctuation means 54 from continuing to operate, stopping the application of the heating amount S2 change cycle to the side coil 11-1 and bottom coil 11-2, which are the driven heating coils 11, thereby suppressing the temperature detected by the pot sensor 12 from following the change in heating amount S2. Furthermore, the rice cooking control means 51 controls the solenoid 35 to rotate the pressure regulating valve 34 to open the steam discharge path 33, thereby connecting the inside of the pot 4 to the outside of the main unit 1, and releasing steam from the food being cooked through the steam discharge path 33 to the outside of the main unit 1 through the steam vent 15. In addition, the display control means 53 controls the LED display unit 17 to turn off the "pressure" process LED display unit.

[0065] The rice cooking control means 51, upon receiving a temperature detection signal from the pot sensor 12 indicating that the pot temperature has dropped to a predetermined temperature, for example, 100°C, controls the heating amount of the heating coil 11 to increase for a short period of time. After this short period, it controls the heating coil 11 to return to the heating amount before the increase in the steaming process, thereby removing excess moisture from the cooked rice and improving its taste.

[0066] When the rice cooking control means 51 receives a timing signal from the timing means 45 indicating that a predetermined time has elapsed, the steaming process ends and the rice cooking process is completed, and the process transitions to the warming process controlled by the warming control means 52.

[0067] Here, we will explain in detail the characteristics of the operation related to the heating amount fluctuation means 54 in particular. For the sake of explanation, from here on, the heating coils 11, namely the side coil 11-1 and the bottom coil 11-2, will be treated as representative heating means, and only the heating amounts of the side coil 11-1 and the bottom coil 11-2 will be mentioned. In this embodiment, during the soaking and boiling heating processes, while the cooking control means 51 is heating the pot 4 in a first pattern, the heating amount fluctuation means 54 causes a change in the heating amount S2 to the pot 4 over time in a second pattern different from the first pattern, making it possible to cook the food to be cooked in the pot 4 with heating similar to that of a traditional Japanese hearth.

[0068] As shown in Figure 8, the heating amount fluctuation means 54, which is a heating amount variable means, is configured to change the heating amount S of the side coils 11-1 and bottom coils 11-2, which are heating means, in a second pattern in which the heating amount S2 is periodically repeated between an upper limit S2max of a heating amount S2 that is greater than the reference value S1ave and a lower limit S2min of a heating amount S2 that is smaller than the reference value S1ave, using the heating amount S1 performed by the first pattern executed by the rice cooking control means 51 as a reference value S1ave.

[0069] For example, in the high heat setting mentioned above, the heating amount fluctuation means 54 is configured to periodically change the output of the inverter in one cycle C, from 1200W → 1240W → 1280W → 1320W → 1360W → 1400W → 1360W → 1320W → 1280W → 1240W → 1200W, setting the upper limit S2max of the heating amount S2 to 1400W and the lower limit S2min of the heating amount S2 to 1200W. In this case, the average heating amount S2 will be 1300W. By making this 1300W heating amount S2 equivalent to the heating amount S1 by the conventional rice cooking control means 51 as a reference value S1ave, it is possible to prevent the food being cooked in the pot 4 from being overcooked or undercooked, even when taking into account the fluctuations in the heating amount S2 caused by the heating amount fluctuation means 54.

[0070] Furthermore, the heating amount fluctuation means 54 is configured to change the heating amount S of the side coil 11-1 and bottom coil 11-2, which are heating means, so as to periodically repeat between the aforementioned upper limit S2max, lower limit S2min, and one or more intermediate values ​​in between.

[0071] For example, in the high heat setting described above, the heating amount fluctuation means 54 sets the upper limit S2max of the heating amount S2 to 1400W and the lower limit S2min to 1200W within one cycle C of the inverter output. Furthermore, intermediate values ​​of the heating amount S2 between these limits, namely 1240W, 1280W, 1320W, and 1360W, are provided, so that in addition to the upper limit S2max and the lower limit S2min, multiple intermediate values ​​are periodically repeated. In this case, there may be any number of intermediate values ​​for the heating amount S2 of the side coil 11-1 and the bottom coil 11-2, for example, there may be only one, namely 1300W. Furthermore, in the aforementioned high heat setting, the heating amount S2 is varied in 40-watt increments as an intermediate value between 1200W and 1400W. However, in this embodiment, the intermediate value of the heating amount S2 can be set even more precisely, allowing it to be varied in 10-watt increments as an intermediate value for both the high and low heat settings. Therefore, the fluctuation change of the heating amount S2 by the heating amount fluctuation means 54 can be made more detailed at the implementation level, and it is possible to cook the food in the pot 4 with heating that is closer to the form of cooking in a traditional Japanese stove. In addition, in this embodiment, the output change amount E, which is the difference between the upper limit value S2max and the lower limit value S2min of the heating amount S2, is set to 1400W-1200W=200W, but it may also be 100W or 300W, and the value of the output change amount E can be set arbitrarily.

[0072] In the example above, the heating amount fluctuation means 54 is set to change the heating amount S2 cycle by 1 second for a fierce flame and 7 seconds for a gentle flame. For example, in the "soaking and cooking" process, in order to achieve a low flame and a gentle flame, the output maintenance time D was set to 0.7 seconds to correspond to setting one cycle C to 7 seconds. However, the output maintenance time D could also be set to 1 second, and the output maintenance time D does not have to be constant for all outputs in one cycle, but can be arbitrarily changed for each output.

[0073] Here, "fluctuation" refers to unpredictable spatial or temporal changes or movements, and "unpredictable" means lacking regularity. In other words, "fluctuation" refers to irregular spatial or temporal changes or movements, and includes not only wind movements and river currents, but also the irregular patterns of flames in a wood fire. It is well known that even things that appear constant are not stable and are unpredictable.

[0074] Furthermore, fluctuations in which irregular patterns are mixed within regular patterns are called "1 / f fluctuations," and the degree of fluctuation is expressed by the frequency "f," with the type of fluctuation being "1 / √f," "1 / f," or "1 / f." 2 "1 / f 3 It is also well known that this can be expressed as "..."

[0075] In the example described above, the heating amount fluctuation means 54 was explained as periodically repeating a change in the heating amount S2 over time corresponding to a preset fluctuation for each cycle C. However, the fluctuation pattern may also be changed irregularly by triggering a change in the cooking state that changes with heating of the pot 4, triggered by the temperature detected by the pot sensor 12, the temperature detected by the lid temperature sensor 32, or the pressure detected by the pressure sensor 17, and changing a fluctuation pattern corresponding to a second pattern consisting of various values ​​of the heating amount S2 (upper limit S2max, lower limit S2min, intermediate value) and time elements (cycle C, output maintenance time D) from a predetermined setting.

[0076] For example, if the rate of temperature increase of the lid temperature Tf is smaller than the rate of temperature increase of the pot bottom temperature Tn from immediately after the start of the boiling heating process until the temperature reaches a predetermined 80°C, it can be determined that the temperature rise of the upper part of the pot 4 is slow. Possible causes for this include insufficient heating, too much water being used for cooking, or cold water. In such cases, in traditional hearth cooking, the firewood fire would be increased empirically to adjust the heat.

[0077] Therefore, in this embodiment, in order to achieve the same heat control as cooking in a traditional hearth, immediately after the start of the boiling heating process, if the rate of temperature rise of the lid temperature Tf is smaller than a predetermined value compared to the rate of temperature rise when the bottom temperature Tn of the pot reaches a predetermined temperature, the heating amount fluctuation means 54 is configured such that, during the subsequent heating adjustment period until boiling, the fluctuation pattern of the heating amount S2 to the pot 4, which is set as the second pattern, temporarily changes as the heating amount S2 increases.

[0078] In other words, in the example above, the heating amount fluctuation means 54, in order to achieve a strong flame and intense heat during the "boiling" process until the bottom temperature Tn of the pot reaches a predetermined temperature, set the lower limit S2min to 1200W and the upper limit S2max to 1400W, and periodically changed the heating amount S2 in a 1-second cycle C. However, the lower limit S2min is increased from 1200W to 1300W, or the output maintenance time D during which the heating amount S2 is maintained at the upper limit S2max of 1400W is increased from 100ms (0.1 seconds) to 500ms (0.5 seconds), thereby temporarily increasing the heating amount S2 of the pot 4.

[0079] Furthermore, the control means 41, which is equipped with AI (artificial intelligence) functionality, may be trained to adjust the next heating step according to the progress of rice cooking, such as temperature, pressure, and steam generation, based on actual temperature and pressure data from traditional rice cooking, thereby introducing irregularity into the AI's instructions.

[0080] Furthermore, in this embodiment, the heating amount fluctuation means 54 changes the upper limit S2max and lower limit S2min of the heating amount S2 in accordance with the time-dependent changes in the rice cooking process, which consists of a soaking process and a boiling process. This makes it possible to cook the food to be cooked in the pot 4 with heating that differs for each cooking process and is similar to the form of cooking in a traditional hearth with flickering flames.

[0081] The heating amount fluctuation means 54 is configured to set the heating amount range (range of heating amount S2) that constitutes the key parts of high heat and low heat, for example, from a multi-stage heating amount including an upper limit value S2max, a lower limit value S2min, and an intermediate value. Therefore, there is no need to continuously vary the high-frequency pulse drive signal to the inverter, which simplifies the circuit configuration of the side coil drive means 46 and bottom coil drive means 47, including the inverter, and makes it possible to miniaturize the inverter.

[0082] As described above, the rice cooker of this embodiment includes a pot 4 for containing the food to be cooked, side coils 11-1 and bottom coils 11-2 as heating means for heating the pot 4, a pot sensor 12 as a detection means for detecting the temperature of the pot 4, a cooking control means 51 that changes the amount of heating of the side coils 11-1 and bottom coils 11-2 as the cooking process progresses to cook the food to be cooked, and a heating amount fluctuation means 54 as a heating amount variable means for changing the amount of heating of the side coils 11-1 and bottom coils 11-2 over time, and the cooking process is carried out by the cooking control means 51 detecting boiling of the food to be cooked from the rate of temperature rise of the pot 4 The cooking process includes a boiling heating step to raise the temperature of the pot, and the heating amount fluctuation means 54 changes the heating amount of the side coil 11-1 and the bottom coil 11-2 so as to periodically repeat between an upper limit S2max of the heating amount, a lower limit S2min of the heating amount, and one or more heating amount values ​​between the upper limit S2max and the lower limit S2min of the heating amount until the pot 4 reaches a predetermined temperature during the boiling heating step. During the boiling heating step, the cooking control means 51 is configured not to execute the heating amount fluctuation means 54 during the boiling detection period, which is the period from when the pot 4 reaches a predetermined temperature until the cooking control means 51 detects boiling.

[0083] By configuring the system in this way, it is possible to suppress the temperature detected by the pot sensor 12 from following the change in the amount of heat S2, thereby suppressing its influence on the determination of boiling of the rice being cooked. As a result, rice can be cooked with heating similar to that of a traditional hearth, and boiling can be detected stably.

[0084] Furthermore, in the rice cooker of this embodiment, the rice cooking process includes a soaking process which is performed before the boiling heating process to promote water absorption of the rice to be cooked. In the soaking process, the heating amount fluctuation means 54 is configured to change the heating amount of the side coil 11-1 and the bottom coil 11-2 so as to periodically repeat between an upper limit S2max of the heating amount, a lower limit S2min of the heating amount, and one or more heating amount values ​​between the upper limit S2max and the lower limit S2min. This allows the soaking process to be performed on the rice to be cooked in the pot 4 with heating similar to that of a hearth where the flames flicker over a wood fire.

[0085] Furthermore, in the rice cooker of this embodiment, the rice cooking process includes a boiling continuation process, which is performed after the boiling heating process to maintain the boiling state of the rice to be cooked, and a steaming process to steam the cooked rice. In the boiling continuation process and the steaming process, the rice cooking control means 51 is configured not to execute the heating amount fluctuation means 54, thereby suppressing the temperature detected by the pot sensor 12 from following the change in the heating amount S2, and enabling the temperature of the pot 4 to be stably maintained at a predetermined temperature based on the temperature detection signal from the pot sensor 12.

[0086] Furthermore, the rice cooker of this embodiment has a plurality of heating coils 11, consisting of side coils 11-1 and bottom coils 11-2, as heating means, and the rice cooking control means 51 is configured to control the side coils 11-1 and bottom coils 11-2 so that they are driven starting from the side coil 11-1, which is the uppermost heating coil 11, during the boiling heating process. As a result, the temperature of the rice being cooked can be raised from the upper part of the pot 4, and the temperature of the rice being cooked can be raised in a temperature rise curve similar to that of heating the pot 4 in a hearth.

[0087] Furthermore, in the rice cooking control means 51 of this embodiment, the heating coil 11 is controlled so that the side coil 11-1 and the bottom coil 11-2 are switched and driven at regular intervals, thereby generating alternating external and internal convection within the pot 4, promoting the stirring of the water in the rice being cooked within the pot 4, and reducing uneven heating.

[0088] Furthermore, in the heating amount fluctuation means 54 of this embodiment, the heating amounts of the side coil 11-1 and the bottom coil 11-2 can be changed in increments of 10 watts. This allows for more detailed control of the fluctuations in the heating amount S2 by the heating amount fluctuation means 54 at the implementation level, and enables cooking of the food in the pot 4 with heating that is closer to that of a traditional Japanese hearth.

[0089] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, the "predetermined value," "predetermined temperature," and "predetermined temperature rise rate" that frequently appear in this embodiment do not need to be the same value each time, and may be set to different values. [Explanation of Symbols]

[0090] 4 Pot 11-1 Side coil (heating means, heating coil) 11-2 Bottom coil (heating means, heating coil) 12. Pot sensor (detection means) 51 Rice cooking control means 54 Heating amount fluctuation means (heating amount variable means) S2max: Upper limit of heating amount S2min Lower limit of heating amount

Claims

1. A pot for holding the food to be cooked, A heating means for heating the aforementioned pot, A detection means for detecting the temperature of the pot, A rice cooking control means that changes the amount of heat from the heating means as the process progresses to cook the rice to be cooked, The system includes a variable heating means for changing the amount of heating of the heating means over time, The above process is, The rice cooking control means includes a boiling heating step in which the temperature of the pot is raised from the rate of temperature rise of the pot until the boiling of the rice to be cooked is detected, A soaking and cooking process is performed before the boiling heating process to promote water absorption of the rice to be cooked, The process includes a boiling continuation step performed after the boiling heating step to maintain the boiling state of the cooked rice, The variable heating means, in the boiling heating process, changes the heating amount of the heating means so as to repeat a cycle of stepwise increasing or decreasing the heating amount in order to take an upper limit of the heating amount, one or more heating amount values ​​between the upper limit and the lower limit of the heating amount, and the lower limit, until the pot reaches a predetermined temperature. In the boiling heating step, the rice cooking control means does not execute the variable heating amount means from the time the pot reaches a predetermined temperature until the rice cooking control means detects boiling. In the soaking and cooking process, the variable heating means changes the heating amount of the heating means so as to repeat a cycle of stepwise increasing or decreasing the heating amount so as to sequentially take an upper limit of the heating amount, one or more heating amount values ​​between the upper limit and the lower limit of the heating amount, and the lower limit. A rice cooker characterized in that, during the boiling continuation step, the rice cooking control means does not execute the heating amount variable means.

2. The above process includes a steaming step in which the cooked rice is steamed. The rice cooker according to claim 1, characterized in that, in the steaming process, the rice cooking control means does not execute the variable heating amount means.

3. The heating means has a plurality of heating coils, The rice cooking control means controls the heating means so that it is driven from the uppermost heating coil during the boiling heating process, as described in claim 1.

4. The rice cooking control means controls the heating means so that each of the plurality of heating coils is switched and driven at regular intervals, as described in claim 3.

5. The rice cooker according to claim 1, characterized in that the variable heating means can change the heating amount of the heating means in increments of 10 watts.

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