JP2023136129A - rice cooker - Google Patents

Abstract

To provide a rice cooker capable of accurately determining an amount of a material to be cooked without deteriorating a cooking state of the material to be cooked.SOLUTION: A rice cooker includes a pot 4 for storing rice and water, a heating coil 11 for heating the pot 4, rice cooking control means 51 for controlling the heating coil 11, and a pot sensor 12 for detecting the temperature of the bottom part of the pot 4. The heating coil 11 includes a side coil 11-1 and a bottom coil 11-2. In a volume determination process, which is a process for determining the volume of the material to be cooked, the rice cooking control means 51 controls the heating coil 11 so as to heat the pot 4 without using the bottom coil 11-2, which is the heating coil disposed closest to the pot sensor 12.SELECTED DRAWING: Figure 4

Description

The present invention relates to a rice cooker that can determine the amount of rice to be cooked.

As this type of rice cooker, for example, Patent Document 1 discloses that the water temperature is detected before determining the rice cooking capacity, the detected water temperature is heated when the water temperature is below a predetermined water temperature, and the temperature is corrected. The rice is heated to a predetermined temperature under an appropriate water temperature, and when the predetermined temperature is reached, the heating is paused and the time taken to reach the predetermined temperature again is detected, and the cooking capacity is determined based on this detected time. What is to be done is disclosed.

Japanese Patent Application Publication No. 5-146352

In the rice cooker of Patent Document 1, when determining the rice cooking capacity, both the hot rice heater and the heat retention heater, which are heating means for heating the inner pot, are used for heating, so the rice to be cooked in the inner pot is heated. When there were only a small amount of rice and water, the temperature of the inner pot would rise too much, causing the rice to become gelatinized. In addition, since the rice-cooking heater is placed near the bottom sensor that detects the temperature at the bottom of the inner pot, the bottom sensor is affected by the heating of the rice-cooking heater, which deteriorates the accuracy of temperature detection by the bottom sensor. There were cases where the rice cooking capacity was not determined accurately.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rice cooker that can accurately determine the amount of rice to be cooked without deteriorating the degree of cooking of the rice to be cooked.

The rice cooker of the present invention includes a pot that accommodates rice to be cooked, a heating device that heats the pot, a control device that controls the heating device, and a temperature detection device that detects the temperature at the bottom of the pot. The heating means has a plurality of heating coils, and the control means does not use the heating coil disposed closest to the temperature detection means in the step of determining the amount of the rice to be cooked. The heating means is characterized in that the heating means is controlled so as to heat the pot.

According to the rice cooker of the present invention, it is possible to suppress the temperature detection means from being influenced by the heating of the heating means, and it is possible to suppress deterioration in the accuracy of temperature detection by the temperature detection means.

1 is a perspective view of a rice cooker showing an embodiment of the present invention. It is a longitudinal cross-sectional view of the rice cooker same as above. FIG. 2 is a sectional view and a plan view of the inner frame and the heating coil as seen from the bottom side. It is a block diagram which shows the electrical structure of a rice cooker same as the above. It is a graph showing changes over time in the temperature detected by the pot temperature sensor, the temperature detected by the lid temperature sensor, the output of the bottom coil, and the output of the side coil in the rice cooking process of the same as above. It is a graph showing the change over time of the pot temperature in the capacity determination process according to the amount of rice to be cooked in the conventional rice cooker and the rice cooker of the present embodiment. It is a graph showing the change over time of the temperature detected by the pot temperature sensor, the output of the bottom coil, and the output of the side coil in the heat retention process of the rice cooker showing one embodiment of the present invention. It is a graph which shows the change with time of the detected temperature of a pot temperature sensor, the output of a bottom coil, and the output of a side coil in the heat retention process of the rice cooker which shows the modification of this embodiment.

Hereinafter, preferred embodiments of the rice cooker of the present invention will be described with reference to the accompanying drawings. Note that common parts in all of these drawings are designated by common reference numerals.

1 to 7 show an embodiment of a rice cooker according to the present invention. First, the overall structure of the rice cooker will be explained based on FIGS. 1 and 2. 1 is the main body, which has a substantially rectangular shape with the front and rear faces, left side and right side facing each other when viewed from above, and is open at the top. ing. Reference numeral 2 denotes a lid body that freely opens and closes the top opening of the main body 1, and like the main body 1, it has a substantially rectangular shape with the front and rear faces, left side and right side facing each other when viewed from above, and the top surface is substantially flat. It is composed of The main body 1 has a pot accommodating portion 3 with an open top surface, and when the lid 2 is opened, a bottomed pot 4 serving as a container for storing water and rice to be cooked is placed in the pot accommodating portion. It is configured to be removably housed in 3. The pot accommodating portion 3 is configured by combining a bowl-shaped inner frame 5 made of resin and the like, and the entirety is formed into a cylindrical shape with a bottom.

The pot 4 has a main material 7 made of aluminum having good thermal conductivity, and a heating element 8 made of a magnetic metal plate such as ferritic stainless steel is joined to the main material 7 from the lower side of the outer surface to the bottom. A heating coil 11 is provided on the outer surface of the inner frame 5 facing the bottom surface of the pot 4 from the lower side thereof as a heating means for heating the heating element 8 of the pot 4 by electromagnetic induction. When a high-frequency current is supplied to the heating coil 11, the heating element 8 of the pot 4 generates heat due to the alternating magnetic field generated by the heating coil 11, and the rice to be cooked in the pot 4 is heated during cooking and keeping warm. . Note that the heating coil 11 will be explained in detail later. Further, a pot sensor 12 serving as a pot temperature detection means is disposed at the center of the bottom of the inner frame 5 so as to elastically contact the bottom of the outer surface of the pot 4.

A hinge 13 is provided at the rear of the lid 2 and serves as a connecting portion with the main body 1. Further, a lid operating body 14 is disposed in an exposed state on the front upper surface of the lid body 2, and when this lid body operating body 14 is pushed, the engagement between the main body 1 and the lid body 2 is released, and the main body A hinge spring (not shown) provided at the rear of the upper part of the lid 2 opens the lid 2 around the hinge axis of the hinge 13 as the center of rotation.

A steam port 15 is provided on the rear upper surface of the lid 2 to discharge steam generated from the food to be cooked in the pot 4 to the outside of the rice cooker. In addition to the steam vent 15 and the lid operating body 14, on the top surface of the lid 2, there is an LCD (Liquid Crystal Display) 16 as a screen display section for displaying various information related to rice cooking. The display means 18 is composed of an LED (Light Emitting Diode) display section 17 as a status display section, and a touch sensor, and is disposed above the LCD 16. An operating means 19 for selecting a rice cooking course, etc., is provided. Further, a control PC (Printed Circuit) board 21 is arranged on the lower surface of the display means 18 and the operation means 19.

The LED display section 17 displays the actual status of the rice cooker, and in this embodiment, the "reservation" LED display section lights up when a reservation is set, and when the "keep warm" state is reached, the "keep warm" indicator lights up. When the process LED display section of "Vacuum" lights up and the inside of the pot 4 is brought into a reduced pressure state lower than atmospheric pressure by the decompression means 38, which will be described later, the "vacuum" step LED display section lights up, and the pressure inside the pot 4 is reduced during rice cooking. When the inside of the pot 4 is pressurized from when the rice starts to be heated until the food to be cooked is cooked, the "pressure" process LED display section is configured to light up. 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 section 17. Here, the color of the light when the respective LED display parts of the LED display part 17 are turned on may be made different, so that the current state of the rice cooker can be understood at a glance. Note that in this embodiment, the LED display section 17 is placed immediately in front of the LCD 16, but it may be placed at a position away from the LCD 16. Alternatively, the configuration may be such that the LED display section 17 is excluded and the display contents of the LED display section 17 are displayed on the LCD 16.

The operating means 19 composed of a touch sensor includes, for example, a plurality of components arranged as touch keys in which a transparent electrode part made of a conductive polymer and a contact part connected to the control PC board 21 are connected by pattern wiring. By performing a touch operation on any of the plurality of button display sections displayed on the LCD 16, a touch key arranged above the button display section and corresponding to the button display section is touch-operated. The configuration is such that this button display section is selected.

In this way, considering the user's operability and safety, the lid operating body 14 is placed at the front of the top surface of the rice cooker on the side closest to the user, and the steam port 15 is placed on the side of the rice cooker away from the user. By disposing the display means 18 at the rear of the upper surface, a large space can be secured for the display means 18 between the lid operation body 14 and the steam port 15 on the upper surface of the lid body 2. Since the provided operating means 19 can be provided in a large size, the visibility of the display means 18 and the operability of the operating means 19 can be improved. In addition, other than the operating means 19 above the LCD 16, there are no operating means on the top surface of the lid 2, such as physical keys and buttons such as the rice cooking key and the off key, which are provided in conventional rice cookers. Since the rice cooker is operated only by the operating means 19, the effort of searching for a button during operation can be saved, and operability can be improved. Furthermore, it is possible to create a very smart appearance, and the space in which the display means 18 and operation means 19, which are precision parts, are arranged can be made compact. Furthermore, by removing physical keys, buttons, etc., the top surface of the lid body 2 can be configured to be substantially flat, making it easier to wipe and clean, improving cleaning performance.

An inner lid assembly 23 serving as a lower member of the lid 2 is disposed below the lid 2. The inner lid assembly 23 is made of a metal material and has a disc shape having approximately the same diameter as the upper opening of the pot 4, and includes an inner lid 24 that covers the upper opening of the pot 4, and a space between the inner cover 24 and the pot 4. The inner lid 24 is provided with a lid packing 25 as an elastic member provided around the entire outer circumference of the inner lid 24 in order to seal the inner lid 24, and a pressure regulating part 26 that adjusts the internal pressure of the pot 4. The annularly formed lid packing 25 comes into contact with the upper surface, which is the opening of the pot 4, when the lid body 2 is closed as shown in FIG. This is to close the gap between and seal the steam generated from the pot 4.

Inside the lid 2, a lid opening/closing detection means 27 is provided near the hinge 13 in order to detect whether the lid 2 is opened or closed. Here, the lid opening/closing detection means 27 may be of any detection type, such as an optical type, a mechanical type, or a magnetic type, as long as it can output a detection signal corresponding to the opening/closing of the lid body 2. Further, inside the lid body 2, there are provided a lid heater 31 as a lid heating means for heating the inner lid 24, and a thermistor-type lid temperature sensor 32 for controlling the temperature of the inner lid 24 by the lid heater 31. It will be done. A steam exhaust path 33 is formed inside the lid 2 to communicate the steam port 15 and the pressure regulating section 26 as a path for releasing the steam generated within the pot 4 to the outside.

The pressure regulating section 26 is provided with a pressure regulating valve 34 that opens and closes a steam exhaust path 33 between the inside of the pot 4 and the steam port 15. The pressure regulating valve 34 is ball-shaped and operates in conjunction with a solenoid 35 provided inside the lid body 2. When releasing the steam inside the pot 4 to the outside, the pressure regulating valve 34 opens the steam discharge path 33 and pressurizes or pressurizes the inside of the pot 4. When the pressure is to be reduced, the solenoid 35 rotates the pressure regulating valve 34 so as to close the steam exhaust path 33. When pressurizing, the food to be cooked in the pot 4 is heated by applying high-frequency electricity to the heating coil 11, the food to be cooked boils and steam is generated, and this steam fills the pot 4. When the internal pressure reaches a predetermined value, the steam exhaust path 33 is opened against the weight of the pressure regulating valve 34, thereby maintaining the pressure inside the pot 4 above atmospheric pressure. Further, a pressure sensor 36 (see FIG. 3) is provided inside the lid body 2 facing the pressure regulating section 26 to detect the pressure inside the pot 4.

Reference numeral 38 denotes a pressure reducing means for reducing the pressure inside the pot 4 to be lower than normal atmospheric pressure when the lid 2 is closed to 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 housed in the pot accommodating body 3 and the lid body 2 is closed, so that the pressure regulating valve 34 closes the steam exhaust path 33. decrease. Further, when the pressure inside the pot 4 drops to a certain value below the atmospheric pressure, the operation of the pressure reducing pump 39, which is the operating source of the pressure reducing means 38, is stopped to maintain the pressure inside the pot 4 in a reduced pressure state. Furthermore, 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 reduction pump 39 is stopped and a path (not shown) communicating between the pressure reduction 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.

Additionally, a unitized heating board assembly 42 including a control means 41 is disposed inside the main body 1 . In order to electrically control each part of the rice cooker, the control means 41 includes a control IC 43 that constitutes a microcomputer, and a storage means 44 such as a readable and writable memory that stores various information and data (Fig. 4), a timer 45 such as a timer capable of measuring the time related to rice cooking (see FIG. 4), and the like. In particular, the control means 41 mainly controls 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 mainly controls the lid heater 31 based on the temperature detected by the lid temperature sensor 32. In this way, the temperature of the inner lid 24 facing the food to be cooked is controlled.

FIG. 3 shows a cross-sectional view and a plan view of the inner frame 5 and the heating coil 11 as viewed from the bottom side. To explain the heating coil 11 with reference to the figure, the heating coil 11 of this embodiment is composed of a side coil 11-1 as a first coil and a bottom coil 11-2 as a second coil. has been done. 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, on the outer surface of the pot accommodating portion 3, so as to face the pot 4. Specifically, when the pot 4 is housed in the pot accommodating section 3, the bottom coil 11-2 is disposed as a bottom heater to face the outer surface of the bottom of the pot 4, and the side coil 11-1 is placed under the side. The heater is disposed outside and above the bottom coil 11-2, facing the outer surface of the lower side of the pot 4. The maximum output of the heating coil 11 of this embodiment is, for example, both the side coil 11-1 and the bottom coil 11-2 are configured with 1400 W, but these values are just an example, and may vary depending on the heating characteristics of the rice cooker. The output balance of the side coil 11-1 and the bottom coil 11-2 may be set arbitrarily. In this embodiment, the heating coil 11 is composed of two heating coils, but the present invention is not limited to this, and may be composed of a larger number of heating coils. The respective heating coils are arranged concentrically from the bottom of the pot 4 facing toward the lower side of the pot 4, and a plurality of heating coils are arranged vertically. Further, the side coil 11-1 and the bottom coil 11-2 may each be formed in a spiral shape or concentrically, and there are no particular restrictions on the shape of each heating coil.

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 the part facing the side coil 11-1, first moves. The temperature becomes high, and this heat moves via the main material 7 to the water of the cooked rice that is in contact with the lower part of the side surface. The movement of heat from the cooked rice is mainly carried out along with the movement of water, but in places where rice is present, the movement of water is limited to the narrow spaces between the rice grains of the cooked rice. , the movement of water and heat will be slowed down. On the other hand, in places where there is no rice, the movement of water and heat becomes active due to convection, so the water from the cooked rice that is in contact with the bottom of the side is followed by the rice that does not exist because the rice sinks downward. The water in the upper layer of the object becomes hot. After that, in the middle part of the rice to be cooked, the water and heat in the upper part of the rice to be cooked, which has become a high temperature part, moves to the middle part of the rice to be cooked, which is a low temperature part, and then to the lower part of the rice to be cooked. Moving on. This phenomenon is so-called thermal convection, and in this embodiment, it will be explained as external convection.

Further, when the bottom coil 11-2 is energized, the outer surface of the bottom of the pot 4, which is the part facing the bottom coil 11-2, becomes high temperature first, and this heat comes into contact with the bottom part via the main material 7. Move to the water of the rice to be cooked. Here, in the lower part of the rice to be cooked, the rice to be cooked is sinking downward, so the upper part of the lower part is covered with the rice to be cooked and water, and the temperature and pressure of this water increases. do. After that, the water whose temperature and pressure have increased in the lower layer passes through the gaps between the rice grains of the rice to be cooked and moves upwards, causing the water whose temperature has increased in the lower layer to heat up. The water moves with the heat to the middle layer of the cooked rice, and then moves to the upper layer. This phenomenon is so-called blow-up, and will be described as internal convection in this embodiment.

Therefore, when the side coils 11-1 and the bottom coils 11-2 are alternately energized, external convection and internal convection of heat occur alternately in the rice to be cooked in the pot 4. By promoting the stirring of water, uneven heating can be reduced.

FIG. 4 shows the electrical configuration of the rice cooker in this embodiment. In the figure, the pot sensor 12, the lid temperature sensor 32, the pressure sensor 36, the lid opening/closing detection means 27, and the operating means 19 are electrically connected to the input port of the control means 41, respectively. In addition to the above-mentioned solenoid 35, decompression pump 39, and display means 18, the output port of the control means 41 has a side coil drive means 46 connected to the side coil 11-1, and a side coil drive means 46 connected to the bottom coil 11-2. The connected bottom coil driving means 47 and the lid heater driving means 48 connected to the lid heater 31 are electrically connected to each other.

The side coil drive means 46 receives the heating control signal from the control means 41 and supplies a high frequency current to the side coil 11-1 to energize it, and the bottom coil drive means 47 receives the heating control signal from the control means 41. Upon receiving the signal, a high frequency current is supplied to the bottom coil 11-2 to energize it. These side coil drive means 46 and bottom coil drive means 47 are configured to include, for example, a power supply circuit, an inverter, an IH drive circuit, a switch element, etc. By changing the cycle of the supplied high-frequency current and the ratio of ON time to one cycle (ON time ratio), the output from the side coil 11-1 and the bottom coil 11-2 to the pot 4 can be increased or decreased. can. 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 direct current or an alternating current. In this embodiment, a case will be described in which the energization of the side coil 11-1 and the bottom coil 11-2 is selectively switched by a switch element, but the present invention is not limited to this. Instead, it may include a period in which the side coil 11-1 and the bottom coil 11-2 are energized at the same time.

The control means 41 receives temperature detection signals from the pot sensor 12 and lid temperature sensor 32, a pressure detection signal from the pressure sensor 36, a detection signal from the lid opening/closing detection means 27, and an operation signal from the operation means 19. In response, a display control signal is output to the display means 18, and the side coil drive means 46 and the bottom coil drive means 47, which energize the side coil 11-1 and the bottom coil 11-2 of the heating coil 11, and the lid heater 31 are activated. A heating control signal is outputted to the lid heater driving means 48 to be driven, and a driving control signal is outputted to the solenoid 35 that moves the pressure regulating valve 34 and the pressure reducing pump 39 of the pressure reducing means 38, respectively. This control means 41 has a control IC 43 equipped with a rice cooking control means 51, a heat retention control means 52, and a display control means 53 as functions on the control sequence of the program read from the storage means 44.

Upon receiving an instruction to start cooking rice from the operating means 19, the rice cooking control means 51 performs a soaking process that promotes water absorption of the rice placed in the pot 4, and a boiling heating process that increases the temperature of the rice to boil in a short time. The rice to be cooked inside the pot 4 is heated to the desired level by sequentially executing each of the following steps: a boiling continuation process to keep the rice boiling, and a steaming process to maintain the rice at a high temperature that does not burn the rice. This system controls rice cooking by heating the rice at a pressure of . Further, the heat retention control means 52 controls the rice inside the pot 4 to be kept at a predetermined heat retention temperature. The display control means 49 generates various control signals based on the operation signals from the operation means 19, and also controls the display operation of the display means 18.

The storage means 44 stores rice cooking courses corresponding to, for example, rice settings, cooking method settings, hardness settings, etc., and the rice settings and cooking method settings of the rice cooking courses stored in the storage means 44. , hardness settings, etc. are displayed in a selectable manner on the display means 18, and by selecting and setting these using the operation means 19, the rice cooking course is selected and set. The storage means 44 also stores information about the heating coil 11, the lid heater 31, the pressure regulating valve 34, and the pressure reducing means 38, including the timing and output to drive the heating coil 11, the lid heater 31, the pressure regulating valve 34, and the pressure reducing means 38. The side coil 11-1 and the bottom coil 11-2 determine the heating pattern that is the driving pattern, and at what timing and output the side coil 11-1 and the bottom coil 11-2 are energized when the heating coil 11 is driven. A plurality of energization patterns are stored, and the rice cooking control means 51 and the heat retention control means 52 control the heating coil 11, lid heater 31, pressure regulating valve 34, and pressure reduction according to these heating patterns and energization patterns. controlling means 38;

The energization pattern of this embodiment is a pattern that includes the energization time and output of the side coil 11-1 and the bottom coil 11-2. For example, after energizing the side coil 11-1 with an output W1 and an energization time T1, The coils are switched, the bottom coil 11-2 is energized with output W2 and energization time T2, and this is repeated over a predetermined period. Note that the energization pattern includes patterns in which only one of the coil energization time and output is varied while the other remains unchanged. For example, while the energization time is constant among multiple coils, the output is This includes cases where the output is constant among multiple coils but the energization time is different for each coil.

Here, "switching the energization pattern" means switching the energization pattern itself. To explain using the above example, after energizing the side coil 11-1 with output W1 and energization time T1, the bottom coil 11-2 is energized with output W2 and energization time T2, and then the side coil 11-1 is energized with output W3 and energization time T3 at a predetermined timing, and then the bottom coil 11-1 is energized with output W3 and energization time T3. This refers to switching to an energization pattern in which energization is repeated at output W4 and energization time T4.

Note that the energization pattern may include a switching time during which energization of all coils is turned off when switching the coils. That is, it may be an energization pattern in which one coil is energized for a predetermined energization time and output → switching time 1 → the other coil is energized for a predetermined energization time and output → switching time 2 is repeated as one cycle. Here, the switching time 1 and the switching time 2 may be the same time or may be different times.

The energization time and output of the side coil 11-1 and the bottom coil 11-2 in each energization pattern may be determined by the inventors of the present invention through extensive experiments in each process. For example, it is preferable that the energization time of the side coil 11-1 and the bottom coil 11-2 is several seconds or more, respectively, so that external convection and internal convection of heat are alternately carried out in the food to be cooked in the pot 4 for a predetermined period of time. By causing the above to occur and promoting stirring of the water of the rice to be cooked in the pot 4, uneven heating can be reduced.

Further, the inventor of the present invention has found that it is preferable that the times for generating external convection and internal convection are not the same in one energization pattern. In other words, the energization times of the side coil 11-1 and the bottom coil 11-2 in one energization pattern are not the same, and the energization times of the switched coils may be different before and after switching the coils during repetition. preferable.

In addition, in the heat retention process, as will be described later, there is an energization pattern in which energization of one coil is controlled while the other coil is not energized. In this energization pattern, a cycle is repeated in which one coil is energized for a predetermined energization time and output, and then the coil is not energized for a predetermined time.

Next, the operation of the rice cooker having the above configuration in the rice cooking process will be explained. FIG. 5 shows the pot temperature t1, which is the temperature detected by the pot temperature sensor 12, the lid temperature _t2 , which is the detected temperature by the lid temperature sensor ₃₁ , and the bottom coil 11-2 in the rice cooking process of the rice cooker of this embodiment. The graphs show changes over time in the output P _B of the side coil 11-1 and the output P _S of the side coil 11-1.

Referring to FIG. 5, the operation of this embodiment during rice cooking will be explained. First, rice as the rice to be cooked and water as the liquid are put into the pot 4, and after setting the pot 4 in the pot accommodating section 3, Close the lid body 2. Around this time, when the rice cooker is energized, the main body 1 and the lid 2 enter an initial off (standby) state in which rice is not being cooked or kept warm.

When the operation means 19 operates an instruction to start rice cooking after setting the rice cooking course, the rice cooking control means 51 performs the soaking process for the rice to be cooked in the pot 4 in accordance with the heating pattern set for the current rice cooking course. Each rice cooking operation of a boiling heating process, a boiling continuation process, and a shading process is performed.

During the steaming process, the rice cooking control means 51 controls the operations of the pressure regulating section 26 and the pressure reducing means 38 so that the pressure inside the pot 4 becomes a reduced pressure state lower than atmospheric pressure. Specifically, when the steaming process is started, the rice cooking control means 51 controls the solenoid 35 so that the steam exhaust path 33 is closed by the pressure regulating valve 34. In this state, the rice cooking control means 51 opens the path of the pressure reducing means 38 based on the pressure detected by the pressure sensor 36, and continuously operates the vacuum pump 39 to drain the air inside the sealed pot 4 to the vacuum pump 39. Perform a vacuum to remove it. Further, the display control means 53 controls the LED display section 17 so as to light up the "vacuum" process LED display section. Thereafter, the rice cooking control means 51 controls the pressure reduction means 38 so that the pressure inside the pot 4 is maintained at a constant value or less 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 throughout the entire period of the boiling process.

When the rice cooking process is started, the rice cooking control means 51 outputs a heating control signal to the side coil driving means 46, and causes the side coil 11 to heat the pot 4 at a predetermined output for a _{predetermined} time T1. -1, and after the elapse of time _T1 , the rice cooking control means 51 controls the side coil 11-1 to stop heating the pot 4 for a predetermined time _T2 , and after the elapse of time _T2 A capacity determination step is performed in which the rice cooking capacity, which is the amount of rice to be cooked, is determined based on the temperature _t1 . The predetermined time _T2 is set to a time at which the temperature can be lowered to enable capacity determination after the time _T1 at which heating is stopped has elapsed. In this embodiment, the bottom coil 11-2, which is the heating coil 11 closest to the pan sensor 12, is not used in the capacity determination process, but only the side coil 11-1, which is the heating coil 11 furthest from the pan sensor 12, is used. and heating pot 4. Therefore, it is possible to prevent the pot sensor 12 from being affected by the heating of the heating coil 11, and to suppress deterioration in the accuracy of temperature detection by the pot sensor 12.

Here, in this embodiment, the time _T1 for heating the pot 4 in the capacity determination process is set to 30 seconds or more, and this "30 seconds" is the difference between the minimum capacity, which is the distinction between the minimum capacity determination, and other capacities. This is the time required to make a judgment. Further, the time _T2 for stopping heating of the pot 4 in the capacity determination step is set to 1 minute or more, and this "1 minute" is the time required to determine the minimum capacity and other capacities. Therefore, for example, in a "quick cooking" course, which is a rice cooking course that prioritizes time, the time _T1 may be set to 30 seconds and the time _T2 may be set to 1 minute.

Further, in this embodiment, 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 section 51 receives the detection signal. The side coil 11-1 is controlled to stop heating the pot 4 at the time of reception, and then stop heating the pot ₄ for a predetermined time T2. If the temperature of the rice and water to be cooked exceeds 60℃, the rice will accelerate gelatinization when it absorbs water, and the rice may not be cooked well. By setting the temperature _t1 to be less than 60°C, gelatinization of the rice during water absorption is suppressed.

FIG. 6 shows the changes over time in the pot temperature of the conventional rice cooker and the changes in the pot temperature in the rice cooker according to the present embodiment over time in the capacity determination step of the soaking process, according to the amount of rice to be cooked. Each is shown in a graph. Here, t _0O , t _0B , t _0M , and t _0S indicated by solid lines are graphs of the temperatures detected by the pot sensor 12 when the amount of rice to be cooked is extra-large, large, medium, or small in a conventional rice cooker. Yes, t _1O , t _1B , t _1M , t _1S indicated by dotted lines are the temperatures detected by the pot sensor 12 when the amount of rice to be cooked is extra large, large, medium, or small in the rice cooker of this embodiment. It is a graph of pot temperature _t1 . Conventionally, both the side coil 11-1 and the bottom coil 11-2 are used to heat the pot 4. Especially when the capacity is small, _t0S rises to around 60°C. There were cases where the temperature of the rice rose too high and the rice gelatinized. Therefore, in this embodiment, only the side coil 11-1 is used to heat the pot 4 by suppressing the output of the entire heating coil 11 compared to conventional rice cookers, thereby suppressing the rise in temperature at the bottom of the pot 4. .

Further, in this embodiment, the rice cooking control means 51 determines the rice cooking capacity based on the pot temperature _t1 at the end of the time _T2 . Note that the capacity determination based on the pot temperature t ₁ at the end of time T ₂ is based only on the pot temperature t ₁ at the end of time T ₂ , even if the capacity determination is based on the pot temperature t ₁ at the end of time T ₂ . Even if it is based on the difference between the pot temperature at the start of the cooking process, it is based on the difference between the pot temperature t ₁ at the end of time T ₂ and the pot temperature t ₁ at time T ₁ when heating is stopped. It may be. The pot temperature _t1 at the start of the soaking process may be set to a predetermined fixed value.

In this embodiment, a configuration is adopted in which the rice cooking capacity is determined only based on the pot temperature _t1 at the end of time _T2 . Here, the rice cooking capacity is determined by setting threshold ranges for each case where the amount of rice to be cooked is extra large, large, medium, and small, for example, with respect to the pot temperature at the end of time _T2 . The determination can be made based on which range the pot temperature falls within at the end of _T2 . Then, as shown in FIG. 6, at the end of time T ₂ , the temperature difference between t _1O , t _1B , t _1M , and t _1S of this embodiment is different from that of the conventional t _0O , t _0B , t _0M , and _t0S . That is, the rice cooker of this embodiment can improve the grouping accuracy by an amount corresponding to the larger temperature difference, and can more accurately determine the rice cooking capacity. Note that the present invention is not limited to this, and the method of determining the rice cooking capacity is just one example.

When the rice cooking control means 51 receives a time signal from the time measurement means 45 indicating that the time _T2 has elapsed, the rice cooking control means 51 shifts to the soaking step of the soaking process, and the rice cooking control means 51 detects the temperature at the bottom of the pot 4 using the pot temperature sensor 12. Based on this, a heating control signal is output to the side coil drive means 46 and the bottom coil drive means 47 respectively, and the side coil 11-1 and the bottom coil 11-2 are controlled to be energized alternately, thereby heating the pot 4. Then, as shown in FIG. 5, a soaking process is performed in which the water temperature in the pot 4 is raised to a predetermined temperature, for example, 35 to 55°C, up to 60°C at most, to promote water absorption of the rice. The soaking step is configured to maintain the water temperature in the pot 4 at a predetermined temperature for a predetermined time, for example, about 15 minutes, but this time may be changed arbitrarily.

Specifically, the rice cooking control means 51 alternately energizes the side coil 11-1 and the bottom coil 11-2 with the duty ratio of the bottom coil 11-2 being A% and the duty ratio of the side coil 11-1 being B%. control so that In addition, when there is switching between energization of the side coil 11-1 and energization of the bottom coil 11-2 during the entire period of the rice cooking process, the rice cooking control means 51 controls the side coil 11-1 and the bottom coil 11 at the time of switching. -2 is controlled so as to sandwich the switching time when both are OFF. Note that the length of this switching time may be constant or may be changed depending on the rice cooking process. Alternatively, control may be performed without switching time. In this embodiment, the rice cooking control means 51 controls the side coil 11-1 and the bottom coil 11-2 in a constant energization pattern in the soaking process, regardless of the amount of rice to be cooked determined in the capacity determination process. However, the duty ratio of the side coil 11-1 and the bottom coil 11-2 may be changed in accordance with the amount of rice to be cooked determined in the capacity determination step, and the energization pattern may be controlled to be changed. Thereafter, when the rice cooking control means 51 receives a timing signal indicating that a predetermined period of time has passed since the soaking step, the rice cooking control means 51 ends the soaking step and moves to the next boiling heating step.

When transitioning to the boiling heating process, 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, so that the rice to be cooked in the pot 4 is heated more strongly than in the boiling process. A heating process is performed in which the side coils 11-1 and the bottom coils 11-2 are alternately energized and the rice to be cooked is heated until boiling is detected.

Specifically, when moving to the heating process, the rice cooking control means 51 increases the duty ratio C% of the bottom coil 11-2 a little more than the duty ratio A% during the soaking process at the beginning of the heating process (C >A), and the duty ratio of the side coil 11-1 and the bottom coil 11-2 are made almost the same, and the side coil 11-1 and the bottom coil 11-2 are heated with an output slightly stronger than that in the soaking process. Control is performed using an energization pattern that alternately energizes the Here, in the boiling heating process, the rice cooking control means 51 changes the energization time of the side coil 11-1 and the bottom coil 11-2 according to the amount of rice to be cooked determined in the capacity determination process. The duty ratio of 11-2 is D% when the amount of cooked rice is extra large, E% when the amount of cooked rice is large, F% when the amount of cooked rice is medium, and F% when the amount of cooked rice is small. When G% is set, the duty ratio is set to increase in the order of D<E<F<G, and the duty ratio of the side coil 11-1 is set to D>E>F>G.

Further, when the boiling heating process is started, the rice cooking control means 51 controls the solenoid 35 to rotate the pressure regulating valve 34 so as to open the steam exhaust path 33, thereby communicating the inside of the pot 4 with the outside of the main body 1. In this state, steam from the food to be cooked is discharged to the outside of the main body 1 from the steam port 15 via the steam exhaust path 33. The display control means 53 then controls the LED display section 17 to turn off the "vacuum" process LED display section.

Thereafter, when the rice cooking control means 51 receives a timing signal indicating that a predetermined period of time has elapsed since the start of the boiling heating process from the timing means 45, the rice cooking control means 51 determines the energization time of J seconds for the bottom coil 11-2 and the energization time for the side coil 11-1 in one cycle. The energization time K seconds is the same as or different from the energization time H seconds of the bottom coil 11-2 and the energization time I seconds of the side coil 11-1 in one cycle at the beginning of the heating process. The pattern is energization → switching time → energization of side coil 11-1 → switching time, and the side coil 11-1 and bottom coil 11-2 are alternately operated at the same or lower output than the output at the beginning of the heating process. The energization pattern is controlled for a predetermined period of time to output an output P _B and an output P _S. In addition, in the subsequent boiling heating process, boiling continuation process, and unevenness process, the rice cooking control means 51 controls the side coil 11 in the following pattern: energizing the bottom coil 11-2 → switching time → energizing the side coil 11-1 → switching time. The heating coil 11 is controlled using an energization pattern that alternately energizes the bottom coil 11-1 and the bottom coil 11-2. In addition, the energizing time of the bottom coil 11-2 at this time is set to be longer in the order of extra-large ≦ large ≦ medium ≦ small, while the energizing time of the side coil 11-1 is set as the amount of rice to be cooked becomes longer. The time is set longer in the order of the amount of objects: small ≦ medium ≦ large ≦ extra large. The period of the energization pattern, which is the energization pattern of the side coil 11-1 and the bottom coil 11-2 when the heating coil 11 is driven at this time, is set to be longer in the order of small≦medium≦large≦extra large. The present invention is not limited to these, and the period and setting of the energization pattern are merely examples.

When the rice cooking control means 51 receives a time signal indicating that a predetermined time has elapsed from the timer means 45, the rice cooking control means 51 receives a time signal indicating that a predetermined period of time has elapsed, and then the rice cooking control means 51 receives a time signal indicating that a predetermined period of time has elapsed. A predetermined output is achieved while making the energization time L+M seconds the same or lower than the total energization time J+K seconds of the energization time J seconds of the bottom coil 11-2 and the energization time K seconds of the side coil 11-1 in the previous one cycle. (H+I≧J+K≧L+M), and control is performed using an energization pattern in which the side coil 11-1 and the bottom coil 11-2 are alternately energized. Here, the energization time of the bottom coil 11-2 is set to be longer in the order of extra large ≦ large ≦ medium ≦ small as the amount of cooked rice is, as before, and on the other hand, the energization time of the side coil 11-1 is The time is set to increase in the order of the amount of cooked rice: small≦medium≦large≦extra-large. By heating the rice to be cooked inside the pot 4 using the side coil 11-1 and the bottom coil 11-2 as described above, as shown in _FIG . The lid temperature _t2 detected by the sensor 32 gradually increases.

Thereafter, the rice cooking control means 51 receives a temperature detection signal from the pot sensor 12 that the pot temperature _t1 has reached a predetermined temperature or higher, for example, 90° C. or higher, and/or receives a temperature detection signal from the lid temperature sensor 32. When it is received that the lid temperature _t2 has reached a predetermined temperature or higher, for example, 90° C. or higher, a stable #1 step, which is a boiling detection step for detecting boiling of the rice to be cooked under pressure, is started.

In the stable #1 step, the rice cooking control means 51 controls the solenoid 35 to rotate the pressure regulating valve 34 so as to close the steam exhaust path 33, thereby sealing the inside of the pot 4, as described above. Since the rice to be cooked is strongly heated inside the pot 4, the rice to be cooked is pressurized inside the pot 4 until it reaches atmospheric pressure or higher, for example, 1.2 atm, and in this pressurized state, the rice to be cooked is Can boil water. As a result, by boiling the water for cooking at 105°C (at 1.2 atm), which is the optimum temperature for gelatinization of rice under pressure, it is possible to maintain a balance between the hardness and stickiness of the rice. . Further, the display control means 53 controls the LED display section 17 so as to light up the "pressure" process LED display section. Note that the rice cooking control means 51 may control the solenoid 35 to adjust the pressure inside the pot 4 based on the pressure detected by the pressure sensor 36, for example, by setting the type of rice.

Further, the rice cooking control means 51 determines that the total energization time N+O seconds of the energization time N seconds of the bottom coil 11-2 in one cycle and the energization time O seconds of the side coil 11-1 is the total energization time N+O seconds in one cycle of the immediately preceding heating process. While making the time approximately equal to L + M seconds, the energization time N seconds of the bottom coil 11-2 is slightly shorter than the energization time L seconds of the bottom coil 11-2 in the previous heating process (N < L), and the side The energization time O seconds of the coil 11-1 is made slightly longer than the energization time M seconds of the side coil 11-1 in the previous heating process (O>M), and the side coil 11-1 and the bottom coil 11-2 are alternately connected. It is controlled by the energization pattern that energizes the Therefore, the rice cooking control means 51 controls the bottom coil 11-2 and the side coil 11-1 with different energization patterns in the heating step and the stable #1 step in the boiling heating step. On the other hand, similarly to the heating process, the rice cooking control means 51 controls the bottom coil 11-2 and the side coil 11-1 with different energization patterns depending on the amount of rice to be cooked.

The rice cooking control means 51 also calculates the slope of the detected temperature, which is the degree to which the temperature detected by the pot sensor 12 or the temperature detected by the lid temperature sensor 32 increases in a predetermined period of time. Specifically, the rice cooking control means 51 controls the temperature of the pot 4 from the temperature detected by the pot sensor 12 until the rise in the pot temperature t1, which is the temperature at the bottom of the pot ₄ , becomes below a predetermined temperature increase rate, such as 3° C. or below in 120 seconds. If it is calculated, it is determined that boiling due to a change in the temperature increase rate of the pot temperature _t1 has been detected. Further, if the rice cooking control means 51 calculates that the rise in the lid temperature _t2 , which is the temperature of the inner lid 24, from the temperature detected by the lid temperature sensor 32 has become below a predetermined temperature increase rate, such as 1° C. or less in 60 seconds, the rice cooking control means 51 can close the lid. It is determined that boiling due to a change in the temperature increase rate of temperature t2 has been detected. When the rice cooking control means 51 detects boiling due to a change in the temperature increase rate of the pot temperature t ₁ and also detects boiling due to a change in the temperature increase rate of the lid temperature t ₂ , the rice cooking control means 51 moves to the next boiling continuation step. . Note that the predetermined temperature increase rates of the pot temperature _t1 and the lid temperature _t2 for detecting boiling are adjusted and set depending on the amount of rice to be cooked determined in the capacity determination step. good. Further, the boiling detection method is just one example, and it may be configured to proceed to the next boiling continuation process when the rice cooking control means 51 determines that boiling is detected due to a change in the temperature increase rate of the pot temperature _t1 . good.

As described above, in the present embodiment, in the boiling heating step in which the temperature of the rice to be cooked is raised to boiling in a short time, the rice cooking control means 51 controls boiling and lid temperature _t2 by changing the temperature increase rate of the pot temperature _t1 . Before boiling due to a change in temperature rise rate is detected, the side coil 11-1 and the bottom coil 11-2 are controlled with three different energization patterns in the heating process, and the side coil 11 is controlled with different energization patterns in the stabilization #1 process. -1 and the bottom coil 11-2, and the energization pattern of the heating coil 11 is switched multiple times. Therefore, the appropriate energization pattern can be finely changed before the water for the rice to be cooked boils, reducing the risk of uneven cooking of the rice. Note that the present invention is not limited to this, and for example, the rice cooking control means 51 may switch the energization pattern of the heating coil 11 when transitioning to the stable #1 step, etc., until the water of the rice to be cooked boils in the boiling heating step. Any configuration may be used as long as the energization pattern of the heating coil 11 is controlled to be switched at least once. The rice cooking control means 51 also controls the bottom coil 11-2 and the side coil 11-1 with different energization patterns depending on the amount of rice to be cooked, and selects an appropriate energization pattern depending on the amount of rice to be cooked. By making detailed changes, the risk of uneven cooking of the rice is reduced.

When the boiling continuation step is started, the rice cooking control means 51 controls the heating coil 11 to turn on and off until the pot temperature _t1 reaches a predetermined temperature based on the temperature detection signal from the pot sensor 12, and also controls the lid temperature. Stabilization is a process in which the lid heater 33 is continuously energized so that the lid temperature _t2 is maintained at a predetermined temperature, such as 98° C. or higher, based on the temperature detected by the sensor 32, and the boiling state of the rice to be cooked is continued. #2 Start process. The energization pattern of the side coil 11-1 and the bottom coil 11-2 during the driving of the heating coil 11 in the stable #2 process has a length of one cycle that stops the driving of the heating coil 11 compared to that in the stable #1 process. time, that is, the OFF time of the heating coil 11 is set to be long.

When the boiling continuation step is started, the rice cooking control means 51 periodically controls the solenoid 35 to be energized and de-energized in order to repeatedly change the pressure inside the pot 4 between normal pressure and pressure higher than atmospheric pressure. A pressure valve 34 periodically opens and closes the steam exhaust path 33.

The rice cooking control means 51 controls the water in the pot 4 to begin to run out in the stable #2 step, and the temperature at the bottom of the pot 4 to reach a predetermined temperature or higher based on the temperature detected by the pot temperature sensor 15, or the temperature rise to zero in 10 seconds. When it is calculated that the temperature has reached a predetermined rate of increase, such as 5° C. or higher, a cooking process is started to detect when the rice to be cooked is finished.

When the cooking process is started, the rice cooking control means 51 controls the solenoid 35 so that the steam exhaust path 33 is closed by the pressure regulating valve 34. In addition, the rice cooking control means 51 increases the energization time Q seconds of the bottom coil 11-2 in one cycle to be larger than the energization time O seconds of the bottom coil 11-2 in one cycle of the stable #2 process (Q>O). , the energization time R seconds of the side coil 11-1 in one cycle is set to less than P seconds (R≦P), the energization time of the side coil 11-1 in one cycle of the stable #2 process, and the side coil 11-1 and the bottom Control is performed using an energization pattern that alternately energizes the coil 11-2. Therefore, the energization time Q seconds of the bottom coil 11-2 in one cycle in the cooking process is set longer than the energization time R seconds of the side coil 11-1. During the cooking process, there is almost no water in the food to be cooked in the pot 4, and no internal or external convection occurs, so by making the energization time of the bottom coil 11-2 longer than that of the side coil 11-1, The water remaining in the inner bottom of the pot 4 can be heated more efficiently from the bottom side of the pot. Here, the energization time of the bottom coil 11-2 is set to be longer in the order of extra-large ≧ large ≧ medium ≧ small as the amount of cooked rice is, as before, and on the other hand, the energization time of the side coil 11-1 is also set. Similarly, the time is set longer as the amount of cooked rice increases in the order of extra-large≧large≧medium≧small.

The rice cooking control means 51 receives from the temperature detection signal from the pot sensor 12 that the pot temperature _t1 has reached a predetermined dry-up temperature, for example, 120°C, or receives the pot temperature from the temperature detection signal from the pot sensor 12. If it is calculated that the rise in temperature _t1 has exceeded a predetermined temperature increase rate, for example, 0.5°C or more in 10 seconds, it is determined that the water inside the pot 4 has run out and the rice to be cooked has been detected. , move on to the next unevenness process.

In the cooking process, the rice cooking control means 51 controls the lid heater 33 to be continuously energized so that the lid temperature _t2 is maintained at a predetermined temperature based on the temperature detected by the lid temperature sensor 32, and prevents exposure to the inner lid 24. The temperature at the bottom of the pot 4 is controlled by continuously controlling the heating coil 11 to turn on and off for a predetermined period of time to prevent the rice from sticking and to maintain a high temperature to the extent that the rice inside the pot 4 does not burn. do. Even in this uneven process, the heating coil 11 is driven/stopped to a certain extent, so the rice cooking control means 51 controls the heating coil 11 using an energization pattern that is substantially the same as the energization pattern in the cooking process, in which the length of one cycle is short. The rice cooking control means 51 also controls the solenoid 35 to rotate the pressure regulating valve 34 so as to open the steam exhaust path 33, thereby communicating the inside of the pot 4 with the outside of the main body 1, and the rice to be cooked. The steam from the main body 1 is discharged from the steam port 15 via the steam exhaust path 33 to the outside of the main body 1. The display control means 53 also controls the LED display section 17 to turn off the "pressure" process LED display section. When the rice cooking control means 51 receives a time signal after a predetermined period of time from the time measurement means 45, the steaming process is completed, the rice cooking process is completed, and the process proceeds to a heat retention process by the heat retention control means 52.

In this embodiment, even after the rice cooking control means 51 detects boiling due to a change in the temperature increase rate of the pot temperature _t1 and boiling due to a change in the temperature increase rate of the lid temperature _t2 , the heating coil is not activated in the cooking process. The energization pattern of the heating coil 11 is switched, and the energization pattern of the heating coil 11 is also controlled to be switched during the unevenness process, so that the water of the rice to be cooked is continuously boiled, and the high temperature is maintained to the extent that the rice does not burn. By carefully changing the appropriate energization pattern when cooking, the risk of uneven cooking of rice is reduced. Note that the present invention is not limited to this, and for example, the rice cooking control means 51 may be configured to control the energization pattern to be switched at least once even after the water of the rice to be cooked has boiled, such as by switching the energization pattern in the steaming process. Good to have.

Next, the operation of the rice cooker having the above configuration in the heat retention process will be explained. FIG. 7 shows the pot temperature t ₁ which is the temperature detected by the pot temperature sensor 12, the output P _B of the bottom coil 11-2, and the output P _S of the side coil 11-1 in the heat retention process of the rice cooker of this embodiment. The graphs show the changes in and over time, respectively.

In this embodiment, as shown in FIG. 7, the heat retention process is subdivided into five periods T ₁ to T ₅ , and the heat retention control means 52 is different for each of these five periods T ₁ to T ₅ . The energization pattern controls the bottom coil 11-2, which is the coil used. That is, the heat retention control means 52 creates an energization pattern in which at least one of the energization time, the output, or the non-energization time of the bottom coil 11-2 is changed from the energization pattern of the previous period every time the periods T ₁ to T ₅ change. is switching to. Note that the present invention is not limited to this, and instead of making all the energization patterns the same throughout the heat retention process, the heat retention control means 52 controls the coils used so that the energization pattern is switched at least once during the heat retention process. Any configuration is fine.

The heat retention process of this embodiment includes a heat retention initial _T1 for a predetermined period of, for example, within 30 minutes from the start of the heat retention process, or a period during which the temperature of the rice is at least a predetermined temperature of, for example, 90°C or higher; It is a predetermined period, for example, within 60 minutes after the initial stage T ₁ and after starting the warming process, and there is a warming decreasing period T ₂ in which the temperature of the rice is gradually lowered, and 60 minutes after starting the warming process. The temperature of the rice is maintained at a low temperature of 70℃ plus or minus 3℃, which is the low temperature range of the thermal insulation temperature range, which is the temperature that can suppress the Maillard reaction in rice. In period _T3 , the temperature of the rice is raised from the set temperature for low heat retention to the temperature for high heat retention, and in the high temperature drop period _T4 , the temperature of the rice is increased to the high temperature side of the heat retention temperature range, for example, 73°C plus or minus 3°C. and a high temperature stability period _T5 in which the temperature is maintained at a high temperature and kept warm.

In the present embodiment, in the heat retention step, the heat retention control means 52 outputs a heating control signal to the bottom coil drive means 47 to control the bottom coil 11-2 to heat the pot 4 at a predetermined output, and controls the bottom coil 11-2 to heat the pot 4 at a predetermined output. The process is controlled using an energization pattern that does not use the side coil 11-1. Therefore, when switching between the side coil 11-1 and the bottom coil 11-2, the generation of mechanical noise caused by a mechanical switch such as a relay is suppressed, thereby reducing noise during the heat retention process.

When moving to the heat retention process, the heat retention control means 52 calculates the temperature of the rice to be cooked based on the temperature _t1 detected by the pot sensor 12, and maintains the temperature of the rice at a predetermined temperature or higher, for example, 90°C or higher. This is the period of initial heat retention _T1 in which the temperature of the pot 4 is controlled by controlling the bottom coil 11-2 to be energized and cut off so that the temperature of the pot 4 is controlled. The heat retention control means 52 also controls the lid heater 22 based on the temperature detected by the lid temperature sensor 32 so that the temperature of the surface of the inner lid 24 facing the pan 4 is higher on average than the temperature of the rice in the pan 4. The temperature of the inner lid 24 is managed by controlling the power on and off. As a result, it is possible to prevent dew condensation on the surface of the inner lid 24 facing the pot 4, preventing dripping onto the rice, maintaining the freshly cooked state, and maintaining the flavor equivalent to freshly cooked rice. Then, the display control means 53 controls the LED display section 17 so as to light up the "keep warm" process LED display section. When the heat retention control means 52 receives a time signal from the timer 45 indicating that a predetermined period of time, such as 30 minutes, has elapsed since the start of the heat retention initial stage _T1 , the temperature retention control means 52 shifts to the heat retention fall period _T2 .

In the heat retention falling period _T2 , the heat retention control means 52 controls the bottom coil 11-2 based on the temperature _t1 detected by the pan sensor 12 to manage the temperature of the pot 4, and for example, 60 minutes after starting the heat retention process. The temperature of the rice inside the pot 4 is lowered to a low heat retention temperature of, for example, 70° C. plus or minus 3° C. over a predetermined period of time such as minutes. At the same time, the heat retention control means 52 controls the lid heater 31 based on the temperature detected by the lid temperature sensor 32 to manage the temperature of the inner lid 24 and prevent dew from forming on the inner lid 24. In addition, during the heat retention fall period _T2 , the heat retention control means 52 may control the solenoid 35 so as to close the steam discharge path 33 with the pressure regulating valve 34, and after degassing in the unevenness step of the rice cooking process, the communication between the inside and outside of the pot 4 is closed. With the water shut off, the temperature of the rice to be cooked is lowered from near the boiling temperature to a temperature that can be kept at a low temperature, so the temperature of gas such as steam in the pot 4 also decreases and becomes liquid such as water. 4 can be brought into a depressurized and degassed state. When the heat retention control means 52 determines that a predetermined period of time has elapsed since the start of the heat retention process and that the temperature of the rice inside the pot 4 has been lowered to the set temperature for low temperature heat retention based on the detected temperature _t1 of the pot sensor 12, the heat retention control means 52 switches the temperature to the next low temperature. Transition to stable period _T3 .

In the low temperature stabilization period _T3 , the heat retention control means 52 controls the bottom coil _11-2 to maintain the temperature of the rice at a low temperature of, for example, 70°C plus or minus 3°C based on the temperature t1 detected by the pot sensor 12. The temperature of the pot 4 is controlled by controlling the power on and off, and the deterioration of the heat-retaining state such as yellowing of the rice inside the pot 4 or emitting a unique odor is suppressed. At the same time, the heat retention control means 52 controls the lid heater 31 based on the temperature detected by the lid temperature sensor 32 to manage the temperature of the inner lid 24 and prevent dew from forming on the inner lid 24. Note that during the low temperature stabilization period _T3 , the heat retention control means 52 may control the solenoid 35 so as to close the steam discharge path 33 with the pressure regulating valve 34, cutting off the communication between the inside and outside of the pot 4 and preventing the flow from the steam hole 17a. It can prevent spoilage bacteria and food poisoning bacteria from entering, and also prevent cold air from entering from outside. Further, when the inside of the pot 4 is in a depressurized and degassed state during the heat retention drop period _T2 , the depressurized and degassed state inside the pot 4 can be maintained. When the heat retention control means 52 receives a time signal from the timer means 45 indicating that a predetermined period of time, such as 6 hours, has elapsed since the start of the low temperature stability period _T3 , the temperature control means 52 shifts to the next high temperature drop period _T4 .

In the high temperature drop period _T4 , the heat retention control means 52 controls the bottom coil 11-2 to be turned on and off, based on the temperature _t1 detected by the pot sensor 12, so that the temperature of the rice is a predetermined temperature higher than the high temperature retention temperature. to control the temperature of pot 4. At the same time, the heat retention control means 52 controls the lid heater 31 based on the temperature detected by the lid temperature sensor 32 to manage the temperature of the inner lid 24 and prevent dew from forming on the inner lid 24. Thereafter, when the heat retention control means 52 determines that the temperature of the rice inside the pot 4 has risen by a predetermined temperature higher than the high-temperature heat retention temperature based on the detected temperature _t1 of the pot sensor 12, it controls the bottom coil 11-2 and controls the bottom coil 11-2. The temperature of the pot 4 is managed based on the detected temperature _t1 of the sensor 12, and the temperature of the rice inside the pot 4 is lowered to a temperature for high temperature keeping. When the heat retention control means 52 determines that the temperature of the rice has fallen to the set temperature for high temperature retention, the process shifts to the next high temperature stable period _T5 .

Note that when the inside of the pot 4 is brought into a depressurized and degassed state in the heat retention process, the heat retention control means 52 controls the bottom coil 11-2 so that the temperature of the rice becomes a predetermined temperature higher than the temperature of the high temperature heat retention during the high temperature drop period _T4. When controlling the power on and off, the solenoid 35 is controlled to rotate the pressure regulating valve 34 so as to open the steam discharge path 33 and release the steam and air in the pot 4 to the outside of the rice cooker. After that, when it is determined that the temperature of the rice inside the pot 4 has risen by a predetermined temperature above the high temperature keeping temperature based on the detected temperature _t1 of the pot sensor 12, the steam discharge path 33 is closed by the pressure regulating valve 34. The solenoid 35 may be controlled so that the temperature of the rice inside the pot 4 is lowered to the high-temperature keeping temperature, and the inside of the pot 4 can be brought into a depressurized and degassed state again.

In the high temperature stable period _T5 , the heat retention control means 52 controls the bottom coil _11-2 to maintain the temperature of the rice at a high temperature of, for example, 73°C plus or minus 3°C based on the temperature t1 detected by the pot sensor 12. The temperature of the pot 4 is managed by controlling the power on and off, and at the same time, the heat retention control means 52 controls the lid heater 31 based on the temperature detected by the lid temperature sensor 32 to manage the temperature of the inner lid 24. 24 to prevent dew from forming on it. Therefore, while suppressing the Maillard reaction in the rice, it is possible to prevent dew condensation on the surface of the inner lid 24 facing the pot 4, thereby preventing dripping of soup onto the rice. Note that during the high temperature stabilization period _T5 , the heat retention control means 52 may control the solenoid 35 so as to close the steam discharge path 33 with the pressure regulating valve 34, cutting off communication between the inside and outside of the pot 4 and preventing the flow from the steam hole 17a. It can prevent spoilage bacteria and food poisoning bacteria from entering, and also prevent cold air from entering from outside. Further, when the inside of the pot 4 is in a depressurized and degassed state during the high temperature drop period _T4 , the depressurized and degassed state inside the pot 4 can be maintained.

As described above, the rice cooker of the present embodiment includes a pot 4 that accommodates rice and water as rice to be cooked, a heating coil 11 as a heating means for heating the pot 4, and a control for controlling the heating coil 11. The heating coil 11 includes a rice cooking control means 51 as a means, and a pot sensor 12 as a temperature detection means for detecting the temperature at the bottom of the pot 4. -2, and the rice cooking control means 51 uses the bottom coil 11-2, which is the heating coil disposed closest to the pot sensor 12, in the capacity determination process, which is the process of determining the amount of rice to be cooked. The configuration is such that the heating coil 11 is controlled so as to heat the pot 4 without heating.

With this configuration, it is possible to prevent the pot sensor 12 from being affected by the heating of the heating coil 11, and it is possible to suppress deterioration in the accuracy of temperature detection by the pot sensor 12.

In addition, the rice cooking control means 51 of the present embodiment controls the heating coil so that the pot 4 is heated using only the side coil 11-1, which is the heating coil disposed farthest from the pot sensor 12, in the capacity determination step. 11, it is possible to suppress the pot sensor 12 from being influenced by the heating of the heating coil 11, and it is possible to suppress deterioration of the temperature detection accuracy of the pot sensor 12. In addition, even when the amount of rice and water to be cooked is small, it is possible to prevent the temperature of the pot 4 from rising excessively, suppressing the gelatinization of the rice and preventing the deterioration of the cooking of the rice to be cooked. Can be suppressed.

Further, the rice cooking control means 51 of the present embodiment controls the temperature when the temperature detected by the pot sensor 12 reaches a predetermined temperature of 60° C. or higher after starting the capacity determination step, or the time for heating the pot 4 as a predetermined time. The heating coil 11 is configured to stop when T ₁ has elapsed, so in the capacity determination process, the pot temperature t ₁ as the temperature detected by the pot sensor 12 is set to be less than 60°C, and the rice absorbs water. Gelatinization of rice can be suppressed.

Further, the rice cooking control means 51 of this embodiment controls the temperature of the rice to be cooked based on the temperature detected by the pot sensor 12 when a predetermined time T2 has elapsed since the heating coil 11 stops heating the pot ₄ . Therefore, the amount of rice to be cooked can be determined based on which range the pot temperature _t1 at the end of time _T2 falls within.

FIG. 8 shows a modification of the rice cooker of this embodiment. The figure shows the pot temperature _t1 , which is the temperature detected by the pot temperature sensor 12, the output P _B of the bottom coil 11-2, and the output P _S of the side coil 11-1 in the heat retention process of this modification. Changes over time are shown in graphs.

In this modification, the heat retention control means 52 controls the side coil drive means 46 during the low temperature stability period _T3 and the high temperature stability period _T5 , which are stable periods in which the temperature is maintained at the low temperature side or the high temperature side of the heat retention temperature range in the heat retention process. A heating control signal is output to the bottom coil driving means 47 to control the side coil 11-1 and the bottom coil 11-2 so as to heat the pot 4 at a predetermined output. Here, in the low-temperature stable period _T3 and the high-temperature stable period _T5 , the heat retention control means 52 energizes the bottom coil 11-2 → switching time → energizes the bottom coil 11-2 → switching time → energizes the side coil 11-1. →The heating coil 11 is controlled using an energization pattern in which the bottom coil 11-2 is energized multiple times (twice in the example of FIG. 8) and then the side coil 11-1 is energized once in a pattern called switching time. Therefore, by controlling the side coil 11-1 and the bottom coil 11-2 by the heat retention control means 52 with such an energization pattern, the number of times the side coil 11-1 and the bottom coil 11-2 are switched is reduced, and relays, etc. By suppressing the mechanical sound generated by the mechanical switch, it is possible to suppress the noise generated during the heat retention process.

Note that the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the spirit of the present invention. For example, settings for the amount of rice to be cooked may be displayed in a selectable manner on the display means 18, and by selecting and setting these using the operation means 19, the rice cooking course can be selected and set. Further, in the capacity determination step, the setting of the amount of the rice to be cooked may be confirmed. Further, the numerical values and the like illustrated in the embodiments are merely examples, and may be changed as appropriate depending on the specifications of the rice cooker.

4 Pot 11 Heating coil (heating means)
11-1 Side coil (heating coil)
11-2 Bottom coil (heating coil)
12 Pot sensor (temperature detection means)
51 Rice cooking control means (control means)
T Time to heat ₁ pot (predetermined time)

Claims (4)

A pot for storing food to be cooked;
heating means for heating the pot;
control means for controlling the heating means;
Temperature detection means for detecting the temperature at the bottom of the pot,
The heating means has a plurality of heating coils,
The control means controls the heating means to heat the pot without using the heating coil disposed closest to the temperature detection means in the step of determining the amount of the rice to be cooked. A rice cooker characterized by: The control means controls the heating means to heat the pot using only the heating coil disposed farthest from the temperature detection means in the step of determining the amount of the rice to be cooked. The rice cooker according to claim 1, characterized in that: The control means stops the heating means when the temperature detected by the temperature detection means exceeds a predetermined temperature or when a predetermined time has elapsed after starting the process of determining the amount of the rice to be cooked. The rice cooker according to claim 1 or 2, characterized in that: 4. Rice cooking according to claim 3, wherein the control means determines the amount of the rice to be cooked based on the temperature detected by the temperature detection means when a predetermined period of time has elapsed since the heating means stopped. vessel.

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