Rice cooker

Abstract

The invention provides a rice cooker for improving the taste of rice. The disclosed rice cooker is provided with: a pot which has a bottom and a wall part and accommodates an object to be cooked including water and rice; a main body which is provided with an upper opening part and accommodates the pot; a coil that inductively heats the bottom; a wall heating element for heating the wall of the pot by heating; a bottom temperature detection unit that detects the temperature of the bottom; an internal temperature detection unit that detects the temperature of air located in the internal space of the pot; and a control unit that controls the power supplied to the coil on the basis of the temperature detected by the bottom temperature detection unit, and that controls the power supplied to the wall heating element on the basis of the temperature detected by the internal temperature detection unit independently of the control of the power supplied to the coil.

Description

Technical Field

[0001] This disclosure relates to a rice cooker. Background Technology

[0002] Patent document 1 discloses a rice cooker comprising: a pot having a heating element at the bottom; a main body for housing the pot; a bottom heating source disposed on the main body to cause the heating element to generate heat; a side heating source disposed on the main body to heat the main body of the pot; and a temperature sensor for detecting the temperature at the bottom of the pot.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-54978 Summary of the Invention

[0006] In the rice cooker of Patent Document 1, there is still room for improvement from the viewpoint of enhancing the taste of the rice.

[0007] The purpose of this disclosure is to improve the flavor of rice.

[0008] One aspect of the rice cooker disclosed herein includes: a pot having a bottom and a wall extending from the outer edge of the bottom for holding a food containing water and rice; a main body having an upper opening for holding the pot through the upper opening; a coil disposed in the main body for inductively heating the bottom; a wall heating element disposed in the main body for heating the wall of the pot; a bottom temperature detection unit for detecting the temperature of the bottom; an internal temperature detection unit for detecting the temperature of the air located in the internal space of the pot; and a control unit that controls the power supplied to the coil based on the temperature detected by the bottom temperature detection unit, and controls the power supplied to the wall heating element based on the temperature detected by the internal temperature detection unit independently of controlling the power supplied to the coil.

[0009] A rice cooker according to the aforementioned method can improve the flavor of rice. Attached Figure Description

[0010] Figure 1 This is a perspective view of a rice cooker according to an embodiment of the present disclosure, showing the state of the lid being closed.

[0011] Figure 2 This is a perspective view of a rice cooker according to an embodiment of the present disclosure, showing the lid in the open state.

[0012] Figure 3 yes Figure 1A sectional view of the rice cooker along line A1-A1.

[0013] Figure 4 It means Figure 1 A schematic diagram of the general structure of a rice cooker.

[0014] Figure 5 It means Figure 1 A schematic diagram showing the relationship between the temperature of the food being cooked and the power supplied to the bottom heating coil when the rice cooker is cooking.

[0015] Figure 6 It means Figure 1 A schematic diagram showing the relationship between the detected temperatures of various temperature detection units during the heat preservation process of a rice cooker and the power supplied to the wall heating element, the cover heating element, and the bottom heating coil.

[0016] Explanation of reference numerals in the attached figures

[0017] 1: Main body; 1A: Upper opening; 1B: Hinge; 1C: Pot storage; 2: Lid; 2A: Steam outlet; 2B: Inner lid; 2C: Lid heating element; 2D: Internal temperature detection unit; 3: Pot; 3A: Bottom; 3B: Outer edge; 3C: Wall; 3D: Opening; 4: Selection unit; 6: Bottom temperature detection unit; 7: Control unit; 51: Bottom heating coil; 51a: Inner bottom heating coil; 51b: Outer bottom heating coil; 52: Wall heating element; 71: Inverter circuit; 72: Heating element switching unit; 81: Power connection unit; 82: Rectifier circuit. Detailed Implementation

[0018] <Insights that form the basis of this disclosure>

[0019] The inventors conducted in-depth research to improve the flavor of rice, and the following insights were obtained as a result.

[0020] A conventional rice cooker structure is considered as follows: The bottom of the pot is inductively heated using a bottom heating source, which acts as a coil, and heat is conducted from a side heating source, which acts as a self-heating element, to the pot walls. Sometimes, the voltage supplied to the rice cooker from an external power source (e.g., the voltage of a commercial power supply in the area where the rice cooker is used) is not adjusted, but directly applied to the side heating source, which acts as the heating element. In this case, the heating force of the heating element varies depending on the magnitude of the voltage supplied to the rice cooker from the external power source (hereinafter also referred to as the supply voltage).

[0021] On the other hand, voltage and current, with frequency adjusted by the inverter, are supplied to the bottom heating source, which acts as the coil. Therefore, even with varying supply voltages, the heating force of the coil is unlikely to change. As a result, the ratio of the heating force of the bottom heating source to the heating force of the heating element may change due to differences in the supply voltage. This change in ratio reduces the stability of the rice's flavor.

[0022] For example, in conventional rice cookers, during the keep-warm process, power is stopped supplying the bottom and side heating sources when the bottom of the pot reaches a predetermined temperature, and power is resumed when that temperature falls below the predetermined temperature. When the supplied voltage is higher, the side heating sources exert stronger heat, causing the upper part of the rice, which is primarily heated by the side heating sources, to become dry. Conversely, when the supplied voltage is lower, the side heating sources exert weaker heat, and the upper part of the rice remains below the desired keep-warm temperature. In this situation, dew accumulates at the bottom of the pot, and the lower part of the rice exposed to the dew becomes overly soft.

[0023] To suppress such flavor deterioration, it is considered to pre-change the ratio based on the voltage of the external power supply, such as the voltage of the commercial power supply in the region where the rice cooker is used (i.e., the location where the rice cooker is used). However, in this case, multiple control logics corresponding to multiple voltages need to be developed. In addition, if multiple control logics are used separately according to the supply voltage, a unit for detecting the supply voltage needs to be set in the rice cooker, which is disadvantageous from the perspective of space efficiency of the rice cooker body and component cost.

[0024] Therefore, the inventors discovered a structure in which the control unit independently controls the power supplied to the bottom heating coil and the wall heating element based on the detected temperatures of different temperature detection units. According to this structure, the heating force of the wall heating element is independent of the supply voltage and is controlled independently of the heating force of the bottom heating coil; therefore, even with varying supply voltages, the ratio can be maintained at a desired level. This improves the flavor of the rice. Based on this new insight, the inventors have made the following disclosure.

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, in the following description, terms indicating specific directions or positions (e.g., terms such as "up," "down," "right," and "left") are used as needed, but these terms are used to facilitate understanding of the present disclosure with reference to the accompanying drawings and are not intended to limit the technical scope of the present disclosure based on the meaning of these terms. Additionally, the following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0026] <Implementation Method>

[0027] An example of a rice cooker according to an embodiment of the present disclosure will be described. Figure 1 This is a perspective view of a rice cooker according to an embodiment of the present disclosure, showing the state of the lid being closed. Figure 2 This is a perspective view of a rice cooker according to an embodiment of the present disclosure, showing the lid in the open state. Figure 3 yes Figure 1 A sectional view of the rice cooker along line A1-A1.

[0028] like Figure 1 or Figure 2 As shown, the rice cooker of this embodiment has a main body 1 that is generally cylindrical with a bottom and a cover 2 that can be opened and closed freely to close the upper opening 1A of the main body 1.

[0029] like Figure 2 As shown, the main body 1 has a bottomed cylindrical pot storage section 1C for easily detachable storage of the pot 3. The pot 3 stores cooked items such as rice and water. Figure 3 As shown, the pot 3 has a bottom 3A and a wall portion 3C extending upward from the outer edge 3B of the bottom 3A when viewed from above. The upper edge of the wall portion 3C defines the opening 3D of the pot 3.

[0030] like Figure 1 and Figure 2 As shown, a selection unit 4 is provided on the side of the main body 1. This selection unit 4 can set the cooking process for the food stored in the pot 3. The selection unit 4 includes, for example, an LCD display that displays various information such as cooking mode and cooking time; and multiple buttons that, in addition to selecting the cooking mode, indicate the start, cancellation, and preset of cooking. The user can select a specific cooking mode and indicate the start of cooking by referring to the various information displayed on the LCD display and using the multiple buttons. In addition, the selection unit 4 may also include a touch panel, for example.

[0031] The cover 2 has a hollow structure and is mounted on the upper part of the main body 1 via a hinge portion 1B. The cover 2 is configured to open and close the upper opening 1A of the main body 1 by rotating around the hinge portion 1B. That is, the cover 2 is configured to be able to close the upper opening 1A of the main body 1 in a closed position (see reference). Figure 1 ) and the opening position that opens the upper opening 1A of the main body 1 (refer to Figure 2 Rotate between )

[0032] like Figure 1 As shown, the lid 2 is provided with a steam outlet 2A for discharging steam generated inside the pot 3 to the outside of the rice cooker. The steam outlet 2A is configured to be in fluid communication with the internal space of the pot 3. In this embodiment, the user can confirm that the food being cooked has overflowed from the pot 3 by seeing it overflow from the steam outlet 2A.

[0033] like Figure 3 As shown, a generally disc-shaped inner cover 2B capable of sealing the opening 3D of the pot 3 is installed on the lower surface side of the cover body 2 (the surface covering the upper opening 1A of the main body 1). In this embodiment, the inner cover 2B is made of metal and is installed on the cover body 2 in a detachable manner. The inner cover 2B is an example of a heating plate in this disclosure.

[0034] Inside the lid 2 are provided: a lid heating element 2C, which heats the inner lid 2B by generating its own heat; and an internal temperature detection unit 2D, which detects the temperature of the air inside the pot 3. Here, the internal space of the pot 3 is, for example, the space between the opening of the pot 3 and the upper surface of the food being cooked.

[0035] In this embodiment, the heating element 2C is a heating resistor located near the inner cover 2B. The heat from the heating element 2C is conducted to the inner cover 2B, thereby heating the inner cover 2B. The inner cover 2B heats the air inside the pot 3 during the cooking and heat preservation processes.

[0036] The internal temperature detection unit 2D is, for example, a temperature sensor that detects the temperature of the inner lid 2B. In this embodiment, the internal temperature detection unit 2D is configured to contact the inner lid 2B. The temperature of the air inside the pot 3 is approximately the same as the temperature of the inner lid 2B; therefore, by detecting the temperature of the inner lid 2B through the internal temperature detection unit 2D, the temperature of the air inside the pot 3 can be detected. The temperature detected by the internal temperature detection unit 2D can be approximately the same as the temperature of the top of the rice.

[0037] The rice cooker of this embodiment includes: a bottom heating coil 51 disposed on the main body 1 to inductively heat the bottom 3A of the pot 3; a wall heating element 52 to heat the wall 3C of the pot 3; a bottom temperature detection unit 6 to detect the temperature of the bottom 3A of the pot 3; and a control unit 7 to perform a rice cooking process and a heat preservation process following the rice cooking process.

[0038] The bottom heating coil 51 is configured to face the bottom 3A of the pot 3. In this embodiment, the bottom heating coil 51 includes: an annular inner bottom heating coil 51a, which is configured to face the center of the bottom 3A of the pot 3; and an annular outer bottom heating coil 51b, which is configured to face the corner of the bottom 3A of the pot 3. The inner bottom heating coil 51a induction heats the center of the bottom 3A of the pot 3. In a top view taken from the depth direction of the pot storage section 1C, the outer bottom heating coil 51b is located outside the inner bottom heating coil 51a and induction heats the outer edge 3B of the bottom 3A of the pot 3.

[0039] The wall heating element 52 heats the wall 3C of the pot 3 by generating heat itself. For example, the wall heating element 52 is disposed inside the main body 1 and arranged around the pot 3 opposite to the wall 3C. In this embodiment, the wall heating element 52 is a heating resistor, and the wall 3C is heated by heat conduction through the wall heating element 52. During the cooking and heat preservation processes, the wall heating element 52 mainly heats the upper part of the food being cooked (or rice) via the wall 3C.

[0040] The bottom temperature detection unit 6 is, for example, a temperature sensor that detects the temperature of the bottom 3A of the pot 3. In this embodiment, the bottom temperature detection unit 6 is configured to contact the center of the bottom 3A of the pot 3 housed within the main body 1.

[0041] Since the temperature of the pot 3 is approximately the same as the temperature of the food being cooked inside the pot 3, the temperature of the food being cooked inside the pot 3 can be detected by detecting the temperature of the pot 3 by the bottom temperature detection unit 6.

[0042] The control unit 7 controls the heating actions of the bottom heating coil 51, the wall heating element 52, and the lid heating element 2C based on the detected temperatures of at least one of the internal temperature detection unit 2D and the bottom temperature detection unit 6, thereby executing the cooking process and the heat preservation process. In this embodiment, the control unit 7 is located inside the main body 1 and below the pot 3.

[0043] Figure 4 It means Figure 1 A block diagram of the general structure of the rice cooker. The rice cooker of this embodiment also includes: a power connection part 81, which can be connected to a power source that supplies power to the rice cooker; and a rectifier circuit 82, which is connected between the power connection part 81 and the bottom heating coil 51.

[0044] The power connection portion 81 is, for example, a connection portion that connects to an external power source such as a commercial power supply, generator, or energy storage device. For connection to an external power source, a portion of the power connection portion 81 is exposed to the outside, but... Figure 1 and Figure 2 The details have been omitted. In this embodiment, the power connection 81 is a plug that connects to a socket. Alternating current (AC) voltage is supplied to the power connection 81 as power. The rectifier circuit 82 rectifies the AC power supplied via the power connection 81.

[0045] An inverter circuit 71 is connected between the rectifier circuit 82 and the bottom heating coil 51. The inverter circuit 71 converts the DC power or low-frequency current output from the rectifier circuit 82 into a high-frequency current and supplies it to the bottom heating coil 51. The inverter circuit 71 adjusts the power supplied to the bottom heating coil 51 by changing at least one of the current flow rate and frequency of the high-frequency current supplied to the bottom heating coil 51.

[0046] Inverter circuit 71 is connected to control unit 7. For example, control unit 7 is a microcomputer. Control unit 7 outputs a drive signal to drive bottom heating coil 51 to inverter circuit 71. In this embodiment, the drive signal is a pulse width modulation (PWM) signal. A PWM signal is a pulse wave that repeatedly turns on and off in a repetitive cycle, and control is achieved by changing the ratio of the on-time in each cycle (duty cycle). In this embodiment, the larger the duty cycle of the drive signal, the more power is supplied to bottom heating coil 51 per unit time.

[0047] On the other hand, the wall heating element 52 and the cover heating element 2C are not connected to the power connection section 81 via the rectifier circuit 82 and the inverter circuit 71. Therefore, the voltage applied to the power connection section 81 from the external power supply is applied to the wall heating element 52 without being boosted or bucked. That is, the voltage applied to the wall heating element 52 depends on the output voltage of the external power supply. In this embodiment, the voltage applied to the power connection section 81 is also applied to the cover heating element 2C without being boosted or bucked.

[0048] A heating element switching unit 72 is connected between the power connection unit 81 and the two heating elements 52 and 2C. The heating element switching unit 72 is configured to switch the power supply to the two heating elements 52 and 2C and to stop it.

[0049] The control unit 7 outputs a drive signal to the heating element switching unit 72 for supplying power to the two heating elements 52 and 2C. In this embodiment, the drive signal is a pulse width modulation signal. In this embodiment, the larger the duty cycle of the drive signal, the less power is supplied to each heating element 52 and 2C per unit time.

[0050] The control unit 7 includes a storage unit that stores at least one cooking program for cooking rice and one heat-keeping program for keeping the cooked rice warm. Here, "cooking program" refers to a program that sequentially performs... Figure 5 The five main processes shown—preheating, heating up, power reduction, boiling maintenance, and steaming—include a pre-determined cooking program for each process, including the power-on time, heating temperature, heating time, and heating output. For example, multiple cooking programs correspond to multiple cooking modes that the rice cooker can execute. Additionally, the "warming program" refers to a program where the power-on time, heating temperature, heating time, and heating output are pre-determined during the warming process described later. The control unit 7 executes the cooking and warming processes based on the temperatures detected by the bottom temperature detection unit 6 and the internal temperature detection unit 2D, according to the cooking and warming programs.

[0051] Figure 5 It means in Figure 1A schematic diagram showing the relationship between the temperature of the food being cooked and the electricity supplied to the bottom heating coil during cooking in a rice cooker.

[0052] When the selection unit 4 selects various cooking information and instructs the start of cooking, the control unit 7 performs the preheating process.

[0053] The preheating process involves soaking the rice in water at a temperature lower than the rice's gelatinization initiation temperature (approximately 60°C) to allow the rice to absorb water beforehand. During the preheating process, the control unit 7 controls the bottom heating coil 51 and the two heating elements 52 and 2C to heat the pot 3 to a preheating temperature (e.g., 50°C) lower than the rice's gelatinization initiation temperature, and maintains the food being cooked at this preheating temperature. After a predetermined time (e.g., 20 minutes) following the start of the preheating process, the process transitions to the heating phase.

[0054] The heating process is the process of raising the temperature of the food being cooked in the pot 3 to a temperature close to boiling. During the heating process, the control unit 7 controls the bottom heating coil 51 and the two heating elements 52 and 2C to raise the temperature of the food being cooked in the pot 3 to a temperature close to boiling. If the temperature detected by the bottom temperature detection unit 6 rises to a predetermined temperature (e.g., 98°C), the process transitions to the power reduction process.

[0055] The power reduction (hereinafter also referred to as PD) process is a process of reducing the heating power of the bottom heating coil 51 and the two heating elements 52, 2C to prevent the cooked food from overflowing outside the pot 3. The power reduction process ends, for example, after a predetermined time (e.g., 1 minute) has elapsed since the start of the power reduction process. After the power reduction process ends, the process transitions to the boiling maintenance process.

[0056] The boiling maintenance process is a process that maintains the boiling state of the food being cooked in the pot 3 to gelatinize the rice starch and increase the degree of gelatinization to, for example, about 50% to 80%. In the boiling maintenance process, the control unit 7 controls, for example, the bottom heating coil 51 and the two heating elements 52 and 2C to heat the pot 3 with a lower heating amount than in the heating process. When the moisture in the pot 3 has disappeared and the temperature detected by the bottom temperature detection unit 6 reaches or exceeds the boiling point of water (for example, 130°C), the process transitions to the steaming process.

[0057] The steaming process utilizes residual heat to evaporate excess moisture, thereby increasing the rice's gelatinization level to nearly 100%. During the steaming process, the control unit 7, for example, controls the bottom heating coil 51 and the two heating elements 52, 2C to slowly lower the temperature of the food being cooked to a predetermined steaming temperature (e.g., 100°C), and then maintains that temperature. Alternatively, the control unit 7 controls the bottom heating coil 51 and the two heating elements 52, 2C to heat the pot 3 with a stronger heating force than when maintaining the steaming temperature until the temperature of the food being cooked drops to the steaming temperature. After a predetermined time (e.g., 20 minutes) has elapsed since the start of the steaming process, the cooking process ends, and the process transitions to a heat-keeping process.

[0058] Figure 6 It means Figure 1 A schematic diagram showing the relationship between the detected temperatures of various temperature sensors during the heat preservation process of a rice cooker and the electricity supplied to the wall heating element, the cover heating element, and the bottom heating coil. (See diagram for reference.) Figure 6 As shown, the heat preservation process includes: a cooling process, which lowers the temperature of the food to be cooked to a predetermined heat preservation temperature; and a temperature maintenance process, which maintains the food to be cooked at the heat preservation temperature after the cooling process.

[0059] The cooling process begins simultaneously with the heat preservation process. During the cooling process, the control unit 7 controls the inverter circuit 71 to stop supplying power to the bottom heating coil 51. Additionally, the control unit controls the heating element switching unit 72 to stop supplying power to the wall heating element 52. On the other hand, the control unit 7 controls the heating element switching unit 72 to drive the cover heating element 2C with a duty cycle of 1 / 16.

[0060] During the cooling process, the temperature of the rice and the air inside the pot 3 continuously decreases. Simultaneously, the temperatures detected by the bottom temperature detection unit 6 and the internal temperature detection unit 2D also decrease. When the temperature detected by the bottom temperature detection unit 6 falls below 70°C, the process transitions to a temperature maintenance process.

[0061] In the temperature maintenance process, the control unit 7 independently controls the driving of the bottom heating coil 51, the wall heating element 52, and the lid heating element 2C based on different temperature detection units. Regarding the bottom heating coil 51, the control unit 7 drives the bottom heating coil 51 with a duty cycle of 1 / 16 when the temperature detected by the bottom temperature detection unit 6 is lower than a first temperature. In this embodiment, the first temperature is 70°C. On the other hand, the control unit 7 stops driving the bottom heating coil 51 when the temperature detected by the bottom temperature detection unit 6 becomes higher than or equal to the first temperature. As a result, the temperature of the bottom 3A of the pot 3 and the lower part of the rice is maintained at around the first temperature.

[0062] Regarding the wall heating element 52 and the lid heating element 2C, the control unit 7 drives the wall heating element 52 and the lid heating element 2C with a duty cycle of 16 / 16 when the temperature detected by the internal temperature detection unit 2D is lower than the second temperature. Here, the second temperature is higher than the first temperature. In this embodiment, the second temperature is 74°C. On the other hand, when the temperature detected by the internal temperature detection unit 2D is higher than the second temperature, the control unit 7 stops driving both the wall heating element 52 and the lid heating element 2C. As a result, the temperature of the upper part of the rice and the air in the internal space of the pot 3 is maintained at a second temperature that is higher than the first temperature.

[0063] According to the embodiments of this disclosure, the control unit 7 controls the power supplied to the wall heating element 52 independently of the control of supplying power to the bottom heating coil 51, based on the temperature detected by the internal temperature detection unit 2D. That is, the power supplied to the wall heating element 52 is controlled based on the temperature detected by a temperature detection unit different from that of the bottom temperature detection unit 6, which forms the basis for the control of the bottom heating coil 51. Therefore, even if the voltage supplied to the rice cooker from an external power source (e.g., commercial power in areas where rice cookers are used) varies, the heating power of the wall heating element 52 can be maintained at a predetermined level. Thus, the heating ratio of the bottom heating coil 51 to the wall heating element 52 is maintained in a manner independent of the voltage supplied from the external power source, thereby suppressing the decrease in the stability of the rice flavor due to differences in the voltage of the external power source. Therefore, the flavor of the rice can be improved.

[0064] As a method to maintain the heating ratio independently of the external power supply voltage, multiple control logics can be used based on multiple possible supply voltages (e.g., the voltage of the commercial power supply at the location where the rice cooker is used). However, the more control logics used, the more time and cost are required to develop them. Furthermore, if multiple control logics stored within the rice cooker are used separately according to the supply voltage, a unit for detecting the supply voltage needs to be installed in the rice cooker, which is disadvantageous from the perspective of space efficiency and component cost of the rice cooker body. On the other hand, according to the above embodiment, the desired heating ratio can be achieved independently of the supply voltage using a single control logic; therefore, it is advantageous from the perspective of development time and cost, as well as space efficiency and component cost of the rice cooker body 1, compared to the above method.

[0065] According to the embodiments of this disclosure, a voltage adjusted to a predetermined value by the inverter circuit 71 is applied to the bottom heating coil 51, while a voltage applied to the power connection portion 81 is applied to the wall heating element 52. In this case, the heating force of the bottom heating coil 51 is constant regardless of the supply voltage, while the heating force of the wall heating element 52 varies according to the supply voltage.

[0066] According to the above embodiment, the control unit 7 controls the power supplied to the wall heating element 52 based on the temperature detected by a temperature detection unit different from that of the bottom temperature detection unit 6, which forms the basis for controlling the bottom heating coil 51. Therefore, even with varying supply voltages, the heating force of the bottom heating coil 51 and the wall heating element 52 can be maintained, thus suppressing the decrease in the stability of the rice's flavor due to differences in the voltage of the external power supply. Therefore, the flavor of the rice can be further improved.

[0067] The upper part of the cooked rice is in contact with the air inside the pot 3, and therefore cools down more easily than the lower part. If the temperature of the upper part of the rice drops, dew will form between the rice grains and on the walls of the pot, resulting in more moisture in the upper part of the rice. In addition, when this dew moves downwards due to gravity and accumulates at the bottom 3A of the pot 3, the rice near the bottom 3A may be exposed to the accumulated dew, leading to more moisture.

[0068] According to the embodiment of this disclosure, the control unit 7 drives the wall heating element 52 when the detected temperature of the internal temperature detection unit 2D is lower than a second temperature, and stops the wall heating element 52 when the detected temperature is higher than the second temperature. Here, the second temperature is set to a temperature higher than the first temperature, which serves as the reference for driving and stopping the bottom heating coil 51. This prevents unexpected temperature drops in the upper part of the rice and reduces the amount of condensation inside the pot 3. Therefore, by improving the amount of moisture in the rice, the flavor of the rice can be further enhanced.

[0069] When the pot 3 and the inner lid 2B are heated by different heating elements, the large temperature difference between them can easily degrade the flavor of the rice. For example, if the temperature of the pot 3 is much higher than that of the inner lid 2B, the portion of the rice adjacent to the pot 3 will become dry and yellow due to overheating. On the other hand, condensation is more likely to form on the cooler inner lid 2B. As a result, the upper part of the rice becomes more moist due to the condensation falling from the inner lid 2B, making it prone to turning white. Furthermore, if the temperature of the inner lid 2B is much higher than that of the pot 3, the upper part of the rice will become dry and yellow due to excess radiant heat from the inner lid 2B. Conversely, near the pot 3, condensation occurs due to the lower temperature compared to the upper part of the rice heated by the inner lid 2B, resulting in more moisture and making the rice prone to turning white.

[0070] According to the embodiments of this disclosure, during the heat preservation process, the control unit 7 performs control in the same manner as the control of the wall heating element 52, based on a comparison between the detected temperature of the internal temperature detection unit 2D and the second temperature. That is, the control unit 7 drives the lid heating element 2C when the detected temperature of the internal temperature detection unit 2D is lower than the second temperature, and stops driving the lid heating element 2C when the detected temperature is higher than the second temperature. This makes it easier to maintain the temperature difference between the pot 3 and the inner lid 2B within the desired temperature range. Furthermore, it can suppress unexpected drops in the temperature of the air inside the pot 3 and suppress the amount of condensation produced inside the pot 3. Therefore, by improving the amount of moisture and dryness of the rice, the flavor of the rice can be further enhanced.

[0071] Furthermore, this disclosure is not limited to the above-described embodiments and can be implemented in various other ways. For example, in the above description, the control unit 7 controls the power supplied to the wall heating element 52 based on the detected temperature of a temperature detection unit different from that of the bottom temperature detection unit 6, which forms the basis for the control of the bottom heating coil 51, but this disclosure is not limited to this. For example, the control unit 7 may also perform the above control in at least one of the preheating, heating, PD, boiling maintenance, and steaming processes included in the rice cooking process.

[0072] In the temperature maintenance process, when the detected temperature of the bottom temperature detection unit 6 or the internal temperature detection unit 2D reaches or exceeds the corresponding first temperature or second temperature, the control unit 7 stops the corresponding bottom heating coil 51, wall heating element 52, and cover heating element 2C. However, this disclosure is not limited to this. For example, the control unit 7 may instead stop the bottom heating coil 51 or the two heating elements 52, 2C, and maintain the drive and reduce the duty cycle.

[0073] In the temperature maintenance process, the control unit 7 controls the driving and stopping of both the wall heating element 52 and the cover heating element 2C based on the temperature detected by the internal temperature detection unit 2D, but this disclosure is not limited to this. For example, the control unit 7 can maintain the cover heating element 2C in a driving or stopped state independently of the temperature detected by the internal temperature detection unit 2D during the temperature maintenance process. Alternatively, the control unit 7 can control the driving and stopping of the cover heating element 2C based on the temperature detected by other temperature detection units different from the bottom temperature detection unit 6 and the internal temperature detection unit 2D.

[0074] In the above embodiment, after the detected temperature of the bottom temperature detection unit 6 rises to a predetermined temperature (e.g., 98°C), the process proceeds to the power reduction step, but this disclosure is not limited to this. For example, the bottom temperature detection unit 6 may be disposed on the cover 2 to detect the temperature of the steam generated in the pot 3, and after the detected temperature of the bottom temperature detection unit 6 rises to a predetermined temperature (e.g., 70°C), the process proceeds to the power reduction step.

[0075] By appropriately combining any of the above-described various implementation methods or variations, the respective effects can be achieved. Furthermore, it is possible to combine implementation methods with each other, to combine embodiments with each other, or to combine implementation methods with embodiments, and it is also possible to combine features from different implementation methods or embodiments with each other.

[0076] This disclosure has been fully described with reference to the accompanying drawings and in connection with preferred embodiments, but various modifications and variations will be apparent to those skilled in the art. It should be understood that such modifications and variations are included in this disclosure without departing from the scope of the disclosure according to the appended claims.

[0077] <Summary of Implementation Methods>

[0078] [Project 1]

[0079] A rice cooker comprising: a pot having a bottom and a wall extending from the outer edge of the bottom for holding a food containing water and rice; a main body having an upper opening for holding the pot; a coil disposed on the main body for inductively heating the bottom; a wall heating element disposed on the main body for heating the wall of the pot; a bottom temperature detection unit for detecting the temperature of the bottom; an internal temperature detection unit for detecting the temperature of the air in the internal space of the pot; and a control unit that controls the power supplied to the coil based on the temperature detected by the bottom temperature detection unit, and independently controls the power supplied to the wall heating element based on the temperature detected by the internal temperature detection unit.

[0080] [Project 2]

[0081] According to the rice cooker of Project 1, the rice cooker includes: a power connection portion that can be connected to a power source that supplies power to the rice cooker; and an inverter connected between the power connection portion and the coil, which adjusts the voltage of the current supplied to the coil, and the voltage applied to the power connection portion is applied to the wall heating element.

[0082] [Project 3]

[0083] According to the rice cooker described in Project 1 or 2, the control unit performs a cooking process of cooking the food and a heat preservation process of keeping the cooked rice warm. In the heat preservation process, when the temperature detected by the bottom temperature detection unit is lower than a first temperature, the control unit drives the coil; when the temperature detected by the bottom temperature detection unit is higher than the first temperature, the control unit stops the coil; when the temperature detected by the internal temperature detection unit is lower than a second temperature higher than the first temperature, the control unit drives the wall heating element; when the temperature detected by the internal temperature detection unit is higher than the second temperature, the control unit stops the wall heating element.

[0084] [Project 4]

[0085] According to the rice cooker described in Project 3, the rice cooker comprises: a lid installed on the main body to cover the upper opening in a freely opening and closing manner; a heating plate installed on the lid to cover the opening of the pot when the lid covers the upper opening in a closed state; and a lid heating element disposed on the lid to heat the heating plate. In the heat preservation process, the control unit drives the lid heating element when the temperature detected by the internal temperature detection unit is lower than the second temperature, and stops the lid heating element when the temperature detected by the internal temperature detection unit is higher than the second temperature.

[0086] Industrial utilization potential

[0087] The rice cooker disclosed herein can improve the flavor of rice, and therefore can be used as a rice cooker for both residential and commercial purposes.

Claims

1. A rice cooker, wherein, The rice cooker is provided with: a pot having a bottom and a wall portion extending from an outer edge portion of the bottom, which receives a cooked material containing water and rice; a main body provided with an upper opening portion through which the pot is received; a coil provided to the main body, which inductively heats the bottom; a wall portion heat generating body provided to the main body, which heats the wall portion of the pot by generating heat; a bottom temperature detecting portion which detects the temperature of the bottom; an inside temperature detecting portion which detects the temperature of air in an inside space of the pot; and a control portion which controls the power supplied to the coil based on the detected temperature of the bottom temperature detecting portion, and independently of the control of the power supplied to the coil, controls the power supplied to the wall portion heat generating body based on the detected temperature of the inside temperature detecting portion.

2. The rice cooker according to claim 1, wherein the rice cooker is provided with: a power source connecting portion which can be connected to a power source that supplies power to the rice cooker; and an inverter connected between the power source connecting portion and the coil, which adjusts the voltage of the current supplied to the coil, the voltage applied to the power source connecting portion is applied to the wall portion heat generating body.

3. The rice cooker according to claim 1 or 2, wherein the control portion performs a cooking process of cooking the cooked material and a warming process of warming the cooked rice, in the warming process, the control portion drives the coil when the detected temperature of the bottom temperature detecting portion is less than a first temperature, and stops the coil when the detected temperature of the bottom temperature detecting portion is the first temperature or more, drives the wall portion heat generating body when the detected temperature of the inside temperature detecting portion is less than a second temperature higher than the first temperature, and stops the wall portion heat generating body when the detected temperature of the inside temperature detecting portion is the second temperature or more.

4. The rice cooker according to claim 3, wherein the rice cooker is provided with: a lid body attached to the main body to cover the upper opening portion in an openable and closable manner; a heating plate attached to the lid body to cover the opening portion of the pot in a closed state in which the lid body covers the upper opening portion; and a lid heat generating body provided to the lid body, which heats the heating plate by generating heat, in the warming process, the control portion drives the lid heat generating body when the detected temperature of the inside temperature detecting portion is less than the second temperature, and stops the lid heat generating body when the detected temperature of the inside temperature detecting portion is the second temperature or more. ​ ​

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