Rice cooker

Abstract

To provide a rice cooker capable of adjusting strength of agitation of rice to be cooked generated by decompression.SOLUTION: A rice cooker includes a pot where rice to be cooked is stored, a heating part for hearing the pot, a lid body that can be opened and closed between a closed position and an open position, a pressure valve for opening and closing a communication hole for communicating the internal space of the pot and the outside of the pot, and a control part for controlling the heating part and the pressure valve. The control part executes a rice cooking process including a temperature raising process for heating the pot until the temperature of water reaches about 100°C and a boiling maintaining process for boiling the water after the temperature raising process and maintaining the boiling. The control part heats the pot by the heating part in the state that the pressure valve is closed in the temperature raising process, and after pressuring an internal space to a temperature raising pressure higher than atmospheric pressure, opens the pressure valve to lower the pressure in the internal space from the temperature raising pressure. The control part changes the temperature raising pressure according to the amount of rice to be cooked, and lowers the pressure in the internal space from the temperature raising pressure.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a rice cooker.

Background Art

[0002] Conventionally, as this type of rice cooker, for example, the one described in Patent Document 1 is known. The rice cooker described in Patent Document 1 includes a pot that houses an object to be cooked including rice and water, a heating unit that heats the pot, and a lid that can close the opening of the pot. A communication hole that fluidly communicates the internal space of the pot with the outside of the pot is provided in the lid. The lid has a pressure valve configured to open and close the communication hole. The heating unit and the pressure valve are controlled by a control unit provided in the rice cooker.

[0003] The control unit controls the heating unit and the pressure valve so as to perform a rice cooking process including a water absorption process of absorbing water into the rice and a temperature raising process of heating the water to boiling after the water absorption process. In the temperature raising process, the control unit closes the communication hole with the pressure valve to raise the pressure in the internal space to a pressure higher than the atmospheric pressure, and then opens the communication hole to lower the pressure in the internal space.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the rice cooker of Patent Document 1, there is still room for improvement from the viewpoint of adjusting the strength of stirring of the object to be cooked caused by depressurization.

[0006] Therefore, an object of the present disclosure is to solve the above problems and provide a rice cooker capable of adjusting the strength of stirring of the object to be cooked caused by depressurization.

Means for Solving the Problems

[0007] The rice cooker according to the present disclosure includes a pot for containing the rice and water to be cooked, a heating unit for heating the pot, a lid that can be opened and closed between a closed position closing the opening of the pot and an open position where the opening is opened, a pressure valve for opening and closing a communication hole that communicates the internal space of the pot with the outside of the pot, and a control unit for controlling the heating unit and the pressure valve, the control unit performing a rice cooking process including a temperature rising process of heating the pot by the heating unit with the pressure valve closed until the temperature of the water reaches about 100°C, and a boiling maintenance process of boiling and maintaining the water after the temperature rising process. It is provided with The control unit in the temperature rising process, heats the pot by the heating unit with the pressure valve closed, pressurizes the internal space to a temperature rising pressure higher than the atmospheric pressure, and then opens the pressure valve to lower the pressure of the internal space from the temperature rising pressure. is configured to change the temperature rising pressure according to the amount of the rice and water to be cooked and lower the pressure of the internal space from the temperature rising pressure.

Advantages of the Invention

[0008] According to the present disclosure, the intensity of stirring of the rice and water to be cooked caused by depressurization can be adjusted.

Brief Description of the Drawings

[0009]

Figure 1

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Mode for Carrying Out the Invention

[0010] <Knowledge on which the present disclosure is based> In conventional rice cookers, heating unevenness occurs in the cooked rice depending on the distance from the inner surface of the pot. Specifically, in the vicinity portion of the cooked rice that is located near the inner surface of the pot, it is easy to receive heat from the pot and the temperature tends to rise. On the other hand, in the separated portion that is located away from the inner surface of the pot, it is difficult to receive heat from the pot and the temperature tends not to rise.

[0011] Furthermore, in the vicinity portion, since the temperature is high, gelatinization of rice progresses easily, and the rice grains tend to adhere to each other. The mutually adhering rice grains not only hinder heat conduction from the pot to the separated portion, but also retain the bubbles generated on the inner surface of the pot in the vicinity portion, inhibiting the diffusion of the bubbles into the object to be cooked. When the diffusion of the bubbles is inhibited, the convection of the object to be cooked associated with the diffusion of the bubbles weakens, and the heating unevenness in the object to be cooked becomes even greater.

[0012] In the rice cooker described in Patent Document 1, during the temperature rising process, the control unit controls the pressure valve to reduce the pressure of the internal space of the pot (hereinafter, also simply referred to as the "internal space") from a constant pressure equal to or higher than the atmospheric pressure. Due to this pressure reduction, many bubbles are generated in the object to be cooked. These bubbles move upward in the object to be cooked and stir the object to be cooked between the vicinity portion and the separated portion. Furthermore, these bubbles separate the mutually adhering rice grains in the vicinity portion. As a result, the bubbles generated on the inner surface of the pot by boiling easily reach the separated portion, and in the rice cooking process after the pressure reduction, the heating unevenness in the object to be cooked is suppressed.

[0013] However, when the amount of the object to be cooked is large, heat from the pot is even more difficult to conduct to the separated portion, so the heating unevenness in the object to be cooked becomes even greater. In the rice cooker described in Patent Document 1, since the pressure at the start of the pressure reduction is a constant pressure equal to or higher than the atmospheric pressure, the strength of the stirring in the object to be cooked relatively weakens as the amount of the object to be cooked increases. As a result, when the amount of the object to be cooked is large, there is a possibility that the heating unevenness cannot be sufficiently suppressed.

[0014] On the one hand, when the amount of the cooked rice is large, in the internal space, the height of the upper surface of the cooked rice (for example, the water level) becomes high, and the distance between the upper surface and the lid becomes small. Here, if the upper surface of the cooked rice further rises due to the generation of bubbles by depressurization or suction into the communication hole, there is a risk that the liquid contained in the cooked rice will be discharged to the outside of the pot through the communication hole. That is, the amount of water present in the internal space may decrease. When the amount of water present in the internal space decreases, it becomes difficult to diffuse the rice grains in water and uniformly heat them in the rice cooking process after depressurization, and the taste of the cooked rice may deteriorate. For example, there is a risk that the cooked rice will be cooked harder than the desired hardness, or that the hardness and taste will vary. Therefore, it is required to appropriately adjust the strength of stirring by depressurization.

[0015] Therefore, as a result of intensive studies to adjust the strength of stirring of the cooked rice caused by depressurization, the inventors have found a configuration in which the pressure at the start of the depressurization (hereinafter, also referred to as "heating-up pressure") is changed according to the amount of the cooked rice. According to this configuration, since the pressure difference between the internal space and the outside of the pot during the depressurization is changed according to the amount of the cooked rice, the strength of stirring of the cooked rice caused by depressurization can be adjusted. Based on this new finding, the inventors have arrived at the following disclosure.

[0016] According to a first aspect of the present disclosure, a pot that contains cooked rice containing rice and water, a heating unit that heats the pot, a lid that can be opened and closed between a closed position that closes the opening of the pot and an open position where the opening is opened, a pressure valve that opens and closes a communication hole that communicates the internal space of the pot with the outside of the pot, a control unit that controls the heating unit and the pressure valve, and performs a rice cooking process including a heating-up process of heating the pot until the temperature of the water reaches about 100°C, and a boiling maintenance process of boiling and maintaining the water after the heating-up process, is provided, the control unit, In the temperature-raising step, with the pressure valve closed, the pot is heated by the heating unit, and after pressurizing the internal space to a temperature-raising pressure higher than atmospheric pressure, the pressure valve is opened to reduce the pressure in the internal space from the temperature-raising pressure. The temperature-raising pressure is changed according to the amount of the rice to be cooked, and the pressure in the internal space is configured to be reduced from the temperature-raising pressure. A rice cooker is provided.

[0017] According to a second aspect of the present disclosure, the control unit is configured to increase the temperature-raising pressure as the amount of the rice to be cooked increases, and reduce the pressure in the internal space from the temperature-raising pressure, and provide the rice cooker according to the first aspect.

[0018] According to a third aspect of the present disclosure, the control unit is configured to decrease the temperature-raising pressure as the amount of the rice to be cooked increases, and reduce the pressure in the internal space from the temperature-raising pressure, and provide the rice cooker according to the first aspect.

[0019] According to a fourth aspect of the present disclosure, the lid has an outer lid and an inner lid attached to the outer lid and closing the opening of the pot when the lid is in the closed position. The inner lid is provided with the communication hole that fluidly communicates the internal space of the pot and the outside of the pot when the lid is in the closed position. The inner lid has a pressure valve that is controlled by the control unit and moves between a closed position that closes the communication hole and a communication position that opens the communication hole, and a storage unit configured to store the liquid discharged from the internal space to the outside of the pot through the communication hole. and has In the boiling-maintaining step, the control unit heats the pot by the heating unit while maintaining the pressure valve in the closed position, and pressurizes the internal space to a boiling pressure higher than atmospheric pressure. The pressure valve is moved to the communication position to reduce the pressure in the internal space from the boiling pressure, so that at least a part of the liquid contained in the rice to be cooked is moved to the storage portion through the communication hole due to the pressure difference between the internal space and the outside of the pot. The liquid stored in the storage portion is configured to be stored in the storage portion until the end of the steaming process. Provide a rice cooker according to the third aspect.

[0020] According to the fifth aspect of the present disclosure, The storage portion has a concave shape that is recessed downward when the lid is in the closed position. The communication hole is located above the bottom of the storage portion and outside the storage portion in a plan view of the inner lid when the lid is in the closed position. Provide a rice cooker according to the fourth aspect.

[0021] According to the sixth aspect of the present disclosure, provide a rice cooker according to the fourth or fifth aspect, wherein the storage portion is in fluid communication with the outside of the rice cooker.

[0022] According to the seventh aspect of the present disclosure, in the first half stage of the boiling maintenance process where there is sufficient moisture in the pot, the control unit closes the pressure valve to pressurize the internal space to a boiling pressure higher than the temperature rising pressure, and in the second half stage of the boiling maintenance process where the moisture in the pot decreases, the control unit opens the pressure valve to lower the pressure in the internal space from the boiling pressure, so as to expand the gaps between the grains of rice. Provide a rice cooker according to any one of the fourth to sixth aspects.

[0023] According to the eighth aspect of the present disclosure, The rice cooker further includes a selection unit capable of selecting a cooking time. In the boiling maintenance process, the control unit is configured to increase the boiling pressure as the cooking time selected by the selection unit is shorter, and to lower the pressure in the internal space from the boiling pressure. Provide a rice cooker according to any one of the fourth to seventh aspects.

[0024] According to a ninth aspect of the present disclosure, the control unit performs a steaming process of steaming the rice after the boiling maintenance process, the control unit closes the pressure valve after opening the pressure valve in the boiling maintenance process to pressurize the internal space, and in the steaming process, is configured to gradually or gently reduce the pressure of the internal space. There is provided a rice cooker according to any one of the first to eighth aspects.

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, terms including "upper", "lower", "right", "left", "front", and "rear") are used based on the normal posture of the rice cooker with the lid in the closed position. However, the use of these terms is for facilitating the understanding of the present disclosure with reference to the drawings, and the technical scope of the present disclosure is not limited by the meanings of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0026] <First Embodiment> A rice cooker according to a first embodiment of the present disclosure will be described. FIG. 1 is a schematic cross-sectional view of the rice cooker according to the first embodiment of the present disclosure.

[0027] As shown in FIG. 1, the rice cooker according to the present embodiment includes a substantially bottomed cylindrical rice cooker main body 1 having a pot storage portion 11 formed therein, and a pot 2 stored in the pot storage portion 11 and containing an object to be cooked rice including rice and water. The pot 2 has a pot bottom portion 21, a peripheral wall portion 22 extending upward from the pot bottom portion 21, and a flange portion 23 extending outward from the upper edge of the peripheral wall portion 22. The upper edge of the peripheral wall portion 22 constitutes the upper opening of the pot 2.

[0028] On the upper part of the rice cooker main body 1, an outer lid 3 with a hollow structure that can open and close the opening of the pot storage part 11 is attached. On the lower surface side of the outer lid 3 (the side that covers the upper opening of the pot 2), a substantially disk-shaped inner lid 4 that can seal the upper opening of the pot 2 is detachably attached. In the present embodiment, the outer lid 3 and the inner lid 4 constitute a lid body that can open and close the upper opening of the pot 2 freely. The lid body can be opened and closed between a closed position where the inner lid 4 closes the upper opening of the pot 2 and an open position where the upper opening of the pot 2 is opened.

[0029] The pot storage part 11 of the rice cooker main body 1 is formed in a concave shape that is recessed downward from the upper surface 1a of the rice cooker main body 1. The pot storage part 11 has a cylindrical side wall part 111 arranged so as to have a predetermined gap from the peripheral wall part 22 of the stored pot 2, and a bottom part 112 arranged so as to have a predetermined gap from the bottom part 21 of the pot 2. The upper surface 1a of the rice cooker main body 1 supports the flange part 23 of the pot 2 around the pot storage part 11.

[0030] In the rice cooker shown in FIG. 1, a heating part 5 for heating the pot 2 and the internal space SP1 of the pot 2 is attached. In this specification and the claims, the "internal space of the pot" is the space surrounded by the inner lid 4, the bottom part 21 of the pot, and the peripheral wall part 22 when the lid body is in the closed position. Also, the "outside of the pot" is a place outside the part of the inner lid 4 facing the internal space, the bottom part 21 of the pot, and the peripheral wall part 22 when the lid body is in the closed position.

[0031] The heating part 5 has an inner-bottom heating coil 51, an outer-bottom heating coil 52, a wall heating coil 53, and an inner-lid heating coil 54. The inner-bottom heating coil 51, the outer-bottom heating coil 52, and the wall heating coil 53 are provided inside the rice cooker main body 1 and inductively heat the pot 2. The inner-bottom heating coil 51 is arranged so as to face the periphery of the central part of the bottom part 21 of the pot 2 through the bottom part 112 of the pot storage part 11. The outer-bottom heating coil 52 is arranged so as to face the corner part of the bottom part 21 of the pot 2 through the bottom part 112. The wall heating coil 53 is arranged so as to face the peripheral wall part 22 of the pot 2 through the side wall part 111.

[0032] An opening is provided in the central portion of the bottom 112 of the pot storage section 11. A pot temperature sensor 12 for measuring the temperature of the pot 2 is disposed in the opening so as to be capable of abutting against the bottom 21 of the pot 2 stored in the pot storage section 11.

[0033] The temperature of the pot 2 detected by the pot temperature sensor 12 correlates with the temperature of the internal space SP1 of the pot 2. Therefore, the temperature of the internal space SP1 can be estimated based on the detected temperature of the pot temperature sensor 12. Here, the temperature of the internal space SP1 is substantially the same as the temperature of the object to be cooked. For example, the temperature of the internal space SP1 is calculated by multiplying the detected temperature of the pot temperature sensor 12 by a correlation coefficient obtained experimentally. This calculation process is performed, for example, in the control section 13 described later.

[0034] The outer lid 3 includes an upper outer member 31 and a lower outer member 32 that constitute the outer contour of the outer lid 3. A hinge member (not shown) is provided at the rear portion of the outer lid 3 to connect the lid body to the rice cooker body 1 so as to be openable and closable between a closed position and an open position. The lid body opens and closes between the closed position and the open position by rotating about the hinge member.

[0035] The lower outer member 32 is provided with a recess 321 that is recessed upward at a position facing the inner lid 4 in the vertical direction. A lid body internal space SP2 is formed between the recess 321 and the inner lid 4. The lid body internal space SP2 is outside the pot 2. A steam passage 33 that fluidly communicates the lid body internal space SP2 and the outside of the rice cooker is connected to the top surface of the recess 321 facing the inner lid 4. The steam passage 33 has a first opening end 331 that opens to the top surface of the recess 321 and a second opening end 332 that opens to the upper outer member 31. Note that a steam cylinder having a cylindrical portion inserted into the steam passage 33 may be detachably attached from the upper outer member 31 side to the steam passage 33.

[0036] FIG. 2 is a perspective view of the inner lid in the rice cooker of FIG. 1. As shown in FIGS. 1 and 2, the inner lid 4 includes a substantially disk-shaped inner lid body 41, an annular pot packing 42 protruding downward from the peripheral edge of the inner lid body 41, and an annular outer lid packing 43 provided around the central portion in a plan view of the inner lid 4 and protruding upward. As shown in FIG. 1, the inner lid body 41 has an upper surface 41a facing the outer lid 3 when the inner lid 4 is attached to the outer lid 3, and a lower surface 41b which is the opposite surface. The pot packing 42 contacts the inner surface of the peripheral wall portion 22 of the pot 2 when the lid body is in the closed position. Thereby, the upper opening of the pot 2 is sealed by the inner lid 4. The outer lid packing 43 contacts the inner wall surface of the recess 321 when the inner lid 4 is attached to the outer lid 3. Thereby, the gap between the outer lid 3 and the inner lid 4 is sealed in the recess 321.

[0037] In the inner lid 4, a part of the inner portion of the outer lid packing 43 constitutes a storage portion 44 for storing the liquid discharged from the internal space SP1 to the lid body internal space SP2. In the present embodiment, the storage portion 44 is configured as a part of the inner lid body 41 and is flat. Specifically, the storage portion 44 is a portion of the inner lid body 41 that is not covered by a liquid receiving portion 45, which will be described later, among the outer lid packing 43.

[0038] The storage portion 44 is provided with a steam discharge hole 411 for discharging steam from the internal space SP1, and a communication hole 412 that enables fluid communication between the internal space SP1 and the lid body internal space SP2 when the lid body is in the closed position. A steam temperature sensor (not shown) for detecting the temperature of the steam in the lid body internal space SP2 or the steam passage 33 may be provided in the recess 321 or the steam passage 33.

[0039] The inner lid 4 has a pressure regulating valve 61 that can open and close the steam discharge hole 411. The pressure regulating valve 61 is a valve that suppresses the pressure in the internal space SP1 from rising above a predetermined value (for example, 1.5 atmospheres) higher than the atmospheric pressure. In the present embodiment, the pressure regulating valve 61 includes a closing member 611 that closes the steam discharge hole 411 and a spring 612 that biases the closing member 611 downward so as to close the steam discharge hole 411. According to this configuration, when the pressure in the internal space SP1 rises above a predetermined value higher than the atmospheric pressure, the closing member 611 moves upward against the biasing force of the spring 612 due to the pressure, and the steam discharge hole 411 is opened. On the other hand, when the pressure in the internal space SP1 drops below the predetermined value, the closing member 611 is biased by the spring 612 and moves downward to close the steam discharge hole 411 again. By repeating the opening and closing of the steam discharge hole 411, the pressure in the internal space SP1 is maintained below the predetermined value.

[0040] Note that the pressure regulating valve 61 may be constituted by a ball and may close the steam discharge hole 411 by its own weight. In this case, when the pressure in the internal space SP1 becomes greater than its own weight (for example, when it becomes 1.5 atmospheres or more), the pressure regulating valve 61 is pushed only by the pressure in the internal space SP1, moves away from the steam discharge hole 411, and opens the steam discharge hole 411.

[0041] The inner lid 4 has a pressure valve 62 configured to be movable between a closed position where the communication hole 412 is closed and a communication position where the communication hole 412 is opened. Usually, the pressure valve 62 is maintained in the closed position by a spring attached to the pressure valve 62. When the pressure valve 62 is in the closed position, the communication hole 412 is blocked, so the pressure in the internal space SP1 can rise to a predetermined value at which the steam discharge hole 411 is opened by the pressure regulating valve 61. On the other hand, when the pressure valve 62 is in the communication position, the communication hole 412 is opened, so the internal space SP1 is in fluid communication with the outside of the rice cooker via the communication hole 412, the inner space SP2 of the lid, and the steam passage 33. Thereby, when the pressure valve 62 is in the communication position, the pressure in the internal space SP1 becomes the same atmospheric pressure as the outside of the rice cooker.

[0042] The outer lid 3 is provided with a pressure valve moving mechanism 63 that moves the pressure valve 62 between a closed position and a communication position. The pressure valve moving mechanism 63 is configured to press the pressure valve 62 downward and move it from the closed position to the communication position under the control of a control unit 13 described later. Thereby, the pressure in the internal space SP1 can be reduced from a pressure higher than the atmospheric pressure to the atmospheric pressure. As a specific configuration of the pressure valve moving mechanism 63, a conventionally known configuration can be adopted. When the pressing of the pressure valve 62 by the pressure valve moving mechanism 63 stops, the pressure valve 62 moves back to the closed position by a spring attached to the pressure valve 62.

[0043] As shown in FIGS. 1 and 2, when the inner lid 4 is attached to the outer lid 3, the inner lid 4 has a liquid receiving portion 45 that is located between the storage portion 44 and the hinge member of the outer lid 3 in a plan view of the inner lid 4. FIG. 2 shows the rotation axis A1 of the hinge member assuming a state where the inner lid 4 is attached to the outer lid 3. As shown in FIG. 2, the liquid receiving portion 45 is located between the storage portion 44 and the rotation axis A1 in the front-rear direction. Further, the liquid receiving portion 45 is located between the storage portion 44 and the rear portion 415 of the inner lid 4 in the front-rear direction. The liquid receiving portion 45 is configured to hold the liquid stored in the storage portion 44 when the lid moves from the closed position to the open position.

[0044] As shown in FIG. 2, the liquid receiving portion 45 has a shape that is recessed from the storage portion 44 toward the hinge member along the front-rear direction of the rice cooker. In the present embodiment, the liquid receiving portion 45 has a substantially semicircular shape in a plan view of the inner lid 4 and is located biased toward the rear of the rice cooker inside the outer lid packing 43. The curved portion of the liquid receiving portion 45 in the plan view is located along the outer lid packing 43. On the other hand, the straight portion of the liquid receiving portion 45 in the plan view forms the opening surface 451 of the liquid receiving portion 45. The opening surface 451 extends in a direction intersecting the inner lid body 41 and is adjacent to the storage portion 44. Note that the shape of the liquid receiving portion 45 in the plan view may be circular, elliptical, polygonal, or the like.

[0045] The liquid receiving part 45 may be integrated with the inner lid body 41 or may be detachable from the inner lid body 41. In the present embodiment, the liquid receiving part 45 is removably fixed to the upper surface 41a of the inner lid body 41. By configuring the liquid receiving part 45 to be removable from the inner lid body 41, the cleanability of the inside of the liquid receiving part 45 is improved.

[0046] As shown in FIG. 1, the inner lid heating coil 54 is provided inside the outer lid 3 having a hollow structure and is arranged so as to surround the recess 321 in a plan view of the outer lid 3. The inner lid heating coil 54 inductively heats the inner lid 4 including the storage part 44. When the inner lid 4 is heated by the inner lid heating coil 54, the internal space SP1 and the food to be cooked are also heated by the heat radiated from the inner lid 4.

[0047] In addition, the outer lid 3 is provided with a display operation part 34 that displays various information such as a cooking course and a cooking time, and can select a specific cooking course from a plurality of cooking courses such as a white rice course, a brown rice course, a white rice (soft) course, and a quick cooking course. The display operation part 34 is an example of the "selection part" in the present disclosure. In the present embodiment, in the display operation part 34, the cooking time can be selected in units of, for example, 5 minutes. Thereby, cooking can be performed according to the convenience of the user.

[0048] The display operation part 34 has, for example, a liquid crystal display that displays various information such as a cooking course and a cooking time, and a plurality of buttons that, in addition to selecting a cooking course, instruct the execution of starting, canceling, reserving, etc. of cooking. The user can select a specific cooking course or cooking time by the plurality of buttons while referring to the various information displayed on the liquid crystal display and instruct the start of cooking.

[0049] The rice cooker according to this embodiment includes a pressure detection unit 35 that directly or indirectly detects the pressure in the internal space SP1. In this embodiment, the pressure detection unit 35 is a pressure sensor provided on the outer lid 3. The pressure sensor is provided between the outer lid 3 and the inner lid 4, and measures the pressure in the pressure measurement space that is in fluid communication with the internal space SP1 through a hole (not shown) provided in the inner lid 4. The pressure sensor is, for example, an absolute pressure sensor, a gauge pressure sensor that indicates pressure based on atmospheric pressure, or a differential pressure sensor that indicates a differential pressure with respect to an arbitrary pressure (for example, the pressure outside the rice cooker).

[0050] A control unit 13 is mounted inside the rice cooker main body 1. The control unit 13 includes a storage unit that stores a plurality of rice cooking sequences for cooking rice. Here, the "rice cooking sequence" refers to the procedure of rice cooking in which four main steps of soaking, temperature rise, boiling maintenance, and steaming are performed in order, and the energization time, heating temperature, heating time, heating output, etc. are predetermined in each step. Each rice cooking sequence corresponds to one of a plurality of rice cooking courses. The control unit 13 controls the heating unit 5 and the pressure valve moving mechanism 63 based on the rice cooking course selected by the display operation unit 34, the detected temperature of the pot temperature sensor 12, the hardness of the rice after cooking, and the detected pressure of the pressure detection unit 35 to execute the rice cooking process.

[0051] Next, the operation of the pressure type rice cooker according to this embodiment will be described. FIG. 3 is a graph showing the relationship between the detected temperature of the pot temperature sensor, the water temperature, the pressure in the internal space, and the open / closed state of the pressure valve when rice cooking is performed by the rice cooker according to the first embodiment of the present disclosure.

[0052] First, the pot 2 containing the rice and water to be cooked is set in the pot storage unit 11 by the user. Then, the user selects a rice cooking course using the display operation unit 34. Here, the rice cooking sequence corresponding to each rice cooking course has information on the rice cooking time from the start to the end of the rice cooking process. This rice cooking time varies depending on the brand of rice corresponding to each rice cooking course, the hardness of the cooked rice (for example, firm or soft), etc. Therefore, by selecting a rice cooking course, the user indirectly selects the rice cooking time.

[0053] Also, in this embodiment, at the display operation unit 34, the user can also directly select the length of the cooking time. For example, the user can select the cooking time in 5-minute units within the range of cooking times that enable normal rice cooking.

[0054] After the selection of the rice cooking course or the cooking time, when the start of rice cooking is instructed, the rice cooking process is started under the control of the control unit 13. When the rice cooking process is started, first, the soaking process is started.

[0055] The soaking process is a process of soaking the rice in water at a temperature lower than the gelatinization temperature in advance to allow the rice to absorb water so that the center part of the rice can be sufficiently gelatinized in a later process. In the soaking process of this embodiment, as shown in FIG. 3, the control unit 13 controls the heating operation of the heating unit 5 based on the detected temperature of the pot temperature sensor 12 so as to raise the water temperature in the pot 2 to 40° C. and then maintain the water temperature. The heating amount of the heating unit 5 is controlled by, for example, duty control. Also, the control unit 13 controls the pressure valve moving mechanism 63 so as to move the pressure valve 62 to the communication position at the start of the soaking process. Thereby, the communication hole 412 is maintained in an open state during the soaking process.

[0056] Note that the control unit 13 may maintain the heating unit 5 in a stopped state until the end of the soaking process in the soaking process. In this case, the water in the pot 2 is kept at room temperature (for example, 20° C.).

[0057] When a predetermined time elapses from the start of the soaking process according to the selected rice cooking course, the temperature rising process is entered. In the example shown in FIG. 3, when 7 minutes have elapsed since the start of rice cooking, the process shifts from the soaking process to the temperature rising process.

[0058] The temperature-raising process is a process of heating the pot 2 on high heat until the temperature of the water in the pot 2 (for example, the average water temperature) reaches about 100°C. In the temperature-raising process, the control unit 13 controls the heating unit 5 so that the pot 2 is rapidly heated and the temperature of the water in the pot 2 reaches about 100°C. In the present embodiment, the control unit 13 controls the heating unit 5 so that the temperature of the water in the pot 2 reaches 100°C. Note that the control unit 13 may control the heating unit 5 so that the temperature of the water in the pot 2 reaches a temperature near 100°C. The temperature near 100°C is, for example, a temperature within the range of 100 ± 5°C. The temperature of the water in the pot 2 is detected by, for example, the pot temperature sensor 12 or the steam temperature sensor. Also, during the temperature-raising process, the control unit 13 controls the pressure valve moving mechanism 63 to maintain the pressure valve 62 in the communicating position. Thereby, the pressure in the internal space SP1 is maintained at atmospheric pressure during the temperature-raising process.

[0059] In the temperature-raising process, a temperature difference occurs between the vicinity portion of the water in the pot 2 close to the inner surface of the pot 2 and the separated portion far from the inner surface. Specifically, the water located in the vicinity portion receives heat from the pot 2 and becomes hotter than the water located in the separated portion. Therefore, even before the average temperature of the water in the pot 2 reaches 100°C, bubbles 9 (see FIG. 4) due to the vaporization of the water are generated in the contact region 2a of the inner surface of the pot 2 with the water. At this time, since the steam discharge hole 411 and the communication hole 412 are closed, the pressure in the internal space SP1 rises due to the generation of the bubbles 9.

[0060] During the temperature-raising process in the pot 2, the temperature of the water in the pot 2 rises above the gelatinization start temperature, and the gelatinization of the rice proceeds. As the gelatinization of the rice progresses, an eluate (starch paste) containing starch is generated on the surface of the rice. Since this eluate has a greater viscosity than water, it precipitates and accumulates on the bottom portion 21 of the pot 2. When the grains of rice adhere to each other in the vicinity portion due to the eluate, the heat conduction from the pot to the separated portion is hindered.

[0061] As shown in FIG. 3, in the temperature rising process, the control unit 13 reduces the pressure of the internal space SP1 from a pressure higher than the atmospheric pressure. Here, "pressure reduction" in the description of the present embodiment means that the pressure of the internal space SP1 is reduced from a pressure higher than the atmospheric pressure to the atmospheric pressure. Specifically, when the pressure of the internal space SP1 is the temperature rising pressure P1 higher than the atmospheric pressure, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the communication position. As a result, the communication hole 412 is opened, and the internal space SP1 and the lid body internal space SP2 are in fluid communication. As a result, the pressure of the internal space SP1 drops from the temperature rising pressure P1 to the atmospheric pressure.

[0062] The movement of the rice to be cooked and the eluate during the pressure reduction will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic cross-sectional view showing the movement of bubbles and eluate in the rice to be cooked before the pressure reduction during the temperature rising process. FIG. 5 is a schematic cross-sectional view showing the movement of bubbles and eluate in the rice to be cooked during the pressure reduction during the temperature rising process.

[0063] As shown in FIG. 4, before the pressure reduction in the temperature rising process, bubbles 9 generated by the vaporization of water adhere to the contact area 2a on the inner surface of the pot 2. Since the temperature of the water in the pot 2 is low before the pressure reduction, the bubbles 9 are small and tend to stay in the contact area 2a. Also, at the time before the pressure reduction, eluate 8 generated by the gelatinization of rice has begun to accumulate on the bottom portion 21 of the pot 2.

[0064] As shown in FIG. 5, when the pressure reduction in the temperature rising process occurs, the volume of the air inside the bubble 9 increases due to the pressure reduction of the internal space SP1. As a result, the bubble 9 tends to separate from the contact area 2a. When the bubble 9 separates from the contact area 2a, it moves upward in the water in the pot 2. At this time, the eluate 8 on the bottom portion 21 of the pot 2 is lifted by the upward moving bubble 9 and diffuses in the water. Thereby, the uneven distribution of the eluate 8 on the bottom portion 21 of the pot 2 is reduced.

[0065] Also, when the pressure in the pot 2 is reduced, the air in the pot 2 is rapidly discharged to the outside of the rice cooker through the communication hole 412. At this time, the rice to be cooked in the pot 2 moves upward as if it is pulled upward along with the rapid movement of the air in the pot 2. In other words, the upper surface 71 (for example, the water surface 73) of the rice to be cooked moves from the position before pressure reduction shown by the dashed line in FIG. 5 to a position higher than that shown by the solid line. Along with the upward movement of the entire rice to be cooked, the eluate 8 that had precipitated on the bottom portion 21 of the pot 2 is pulled upward and diffused in the rice to be cooked. Therefore, the uneven distribution of the eluate 8 on the bottom portion 21 of the pot 2 is reduced by the movement of the bubbles in the rice to be cooked and the upward movement of the entire rice to be cooked.

[0066] For example, when the temperature of the water in the pot 2 is 60°C or higher and the pressure in the internal space SP1 is the pressure P1 during temperature increase, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the communication position. When the temperature of the water is 60°C or higher, that is, when the temperature of the water is equal to or higher than the gelatinization start temperature of the rice, in the rice to be cooked, the gelatinization of the rice progresses and there is a high possibility that the eluate 8 is generated. Therefore, by performing pressure reduction when the temperature of the water is 60°C or higher, the diffusion effect of the eluate 8 due to the aforementioned pressure reduction can be obtained more reliably. Also, the higher the temperature of the water in the pot 2 during pressure reduction, the greater the number of bubbles 9 that leave the contact area 2a of the inner surface of the pot 2 during pressure reduction, and the larger the size of each bubble 9. Therefore, from the viewpoint of more reliably obtaining the diffusion effect of the eluate 8 due to the movement of the bubbles 9 in the water, the control unit 13 preferably moves the pressure valve 62 to the communication position when the temperature of the water is 60°C or higher, 65°C or higher, 70°C or higher, 75°C or higher, or 80°C or higher in the temperature increase process.

[0067] In the example shown in FIG. 3, after the pressure in the internal space SP1 is pressurized to 1.3 atmospheres, which is the pressure P1 during temperature increase, the control unit 13 moves the pressure valve 62 to the communication position when the temperature of the water in the pot 2 is about 72°C.

[0068] The control unit 13 lowers the temperature-raising pressure P1 as the amount of the rice to be cooked is larger, and reduces the pressure in the internal space SP1 from the temperature-raising pressure P1. By lowering the temperature-raising pressure P1 when the amount of the rice to be cooked is large, it is possible to suppress the water contained in the rice to be cooked from being discharged to the outside of the pot 2 (for example, the storage unit 44) through the communication hole 412 during depressurization. Also, by raising the temperature-raising pressure P1 when the amount of the rice to be cooked is small, even when the distance D1 (see FIG. 4) between the upper surface 71 of the rice to be cooked and the inner lid 4 is large, the rice to be cooked can be moved upward more reliably.

[0069] For example, the control unit 13 sets the temperature-raising pressure P1 to 1.4 atmospheres when the amount of rice contained in the rice to be cooked is 1 go, 1.3 atmospheres when it is 2 go or 3 go, 1.2 atmospheres when it is 4 go, and 1.1 atmospheres when it is 5 go.

[0070] The amount of the rice to be cooked is estimated based on, for example, the temperature-raising rate of the rice to be cooked until the pressure valve 62 is opened in the temperature-raising process. Also, as the amount of the rice to be cooked, the amount of the rice to be cooked detected by a weight sensor provided in the rice cooker, the amount of rice cooking selected via the display operation unit 34 at the start of rice cooking, etc. can also be adopted.

[0071] As shown in FIG. 3, when a predetermined time has elapsed after the communication hole 412 is opened, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the closed position. Thereby, the communication hole 412 is closed, and the depressurization of the internal space SP1 in the temperature-raising process ends. The depressurization time T1 from the opening to the closing of the communication hole 412 is, for example, 10 seconds. After the communication hole 412 is closed, since the heating by the heating unit 5 continues, the internal space SP1 is pressurized again.

[0072] In the present embodiment, the depressurization in the above-described temperature-raising process is performed twice. In the example shown in FIG. 3, the first depressurization starts at the 15-minute mark from the start of rice cooking, and the second depressurization starts at the 17-minute mark from the start of rice cooking.

[0073] When the temperature of the water in the pot 2 reaches approximately 100°C, the process proceeds to the boiling maintenance step. In the example shown in FIG. 3, at the time when 19 minutes have elapsed since the start of rice cooking, the temperature of the water in the pot 2 reaches 100°C, and the process shifts from the temperature increase step to the boiling maintenance step.

[0074] The boiling maintenance step is a step of boiling and maintaining the water contained in the object to be cooked after the temperature increase step. The control unit 13 continuously controls the pressure valve moving mechanism 63 to maintain the pressure valve 62 in the closed position from the temperature increase step. While the communication hole 412 is closed, the pressure in the internal space SP1 can rise to a predetermined pressure (for example, 1.5 atm) at which the steam discharge hole 411 is opened due to the vaporization of the water in the internal space SP1 into steam.

[0075] In the first half stage of the boiling maintenance step where there is sufficient moisture in the pot 2, the control unit 13 maintains the pressure valve 62 in the closed position and pressurizes the internal space SP1 to a boiling pressure P2 higher than the temperature increase pressure P1. In the present embodiment, the boiling pressure P2 is 1.5 atm, which is higher than the temperature increase pressure P1 of 1.3 atm. That is, in the present embodiment, the boiling pressure P2 is the pressure at which the steam discharge hole 411 is opened by the movement of the closing member 611 of the pressure regulating valve 61. Thereby, the internal space SP1 is pressurized and the boiling point of the water in the pot 2 rises. Further, the control unit 13 controls the heating unit 5 so that the temperature of the water in the pot 2 approaches the boiling point of the water at the pressure of the internal space SP1.

[0076] Here, when the above-described decompression is performed in the temperature increase step, the uneven distribution of the eluate 8 on the bottom portion 21 of the pot 2 of the pot 2 is suppressed, so that it is possible to suppress the unevenly distributed eluate 8 from hindering the convection in the object to be cooked and the heat conduction from the pot 2 to the object to be cooked. As a result, the rate of temperature increase of the water in the pot 2 becomes faster, so that in the boiling maintenance step, the pressure in the internal space SP1 reaches the boiling pressure P2 earlier. In the example shown in FIG. 3, at the time when 22 minutes have elapsed since the start of rice cooking, the pressure in the internal space SP1 has reached the boiling pressure P2.

[0077] When the pressure in the internal space SP1 reaches 1.5 atmospheres, which is the boiling pressure P2, the closing member 611 of the pressure regulating valve 61 moves upward against the biasing force of the spring 612, and the steam discharge hole 411 is opened. On the other hand, when the pressure in the internal space SP1 drops below 1.5 atmospheres, the closing member 611 is biased by the spring 612 and moves downward to close the steam discharge hole 411 again. Therefore, the pressure in the internal space SP1 is maintained at 1.5 atmospheres even when the pressure valve 62 controlled by the control unit 13 closes the communication hole 412.

[0078] In the latter half of the boiling maintenance process when the moisture in the pot 2 decreases, the control unit 13 opens the communication hole 412 to decompress the internal space SP1 from the boiling pressure P2. For example, when the temperature of the water in the pot 2 rises close to the boiling point corresponding to the pressure in the internal space SP1, the control unit 13 opens the communication hole 412 to decompress the internal space SP1 from the boiling pressure P2. Here, "close to the boiling point" includes the actual boiling point and the temperature deviated from the boiling point by the measurement error of the temperature of the water in the pot 2.

[0079] Specifically, in the latter half of the process, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the communication position. When the communication hole 412 is opened, the internal space SP1 and the internal space SP2 of the lid body are in fluid communication, and a rapid decompression occurs in the internal space SP1. In the example shown in FIG. 3, the control unit 13 moves the pressure valve 62 to the communication position at the time when 22 minutes and 30 seconds have elapsed since the start of rice cooking.

[0080] That is, in the present embodiment, after 30 seconds have elapsed since the pressure in the internal space SP1 reached the boiling pressure P2 (1.5 atm), the control unit 13 moves the pressure valve 62 to the communication position to open the communication hole 412. Before the decompression starts after the pressure in the internal space SP1 reaches the boiling pressure P2, the temperature of the water in the pot 2 rises to near the boiling point of water at the boiling pressure P2 (for example, about 112°C at 1.5 atm). During this period, the food to be cooked is heated at a temperature higher than the boiling point of water at atmospheric pressure (about 100°C) for a longer time. As a result, the amount of heat applied to the rice increases and the gelatinization of the rice is promoted, so that the stickiness and taste of the cooked rice can be further enhanced.

[0081] The state of the internal space SP1 before and after the start of the decompression will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic cross-sectional view showing the state of the liquid and rice in the pot before the decompression in the boiling maintenance step. FIG. 7 is a schematic cross-sectional view showing the state of the liquid and rice in the pot during the decompression in the boiling maintenance step.

[0082] As shown in FIG. 6, in the internal space SP1 before the decompression, the entire amount of rice contained in the food to be cooked is covered by bubbles formed by the liquid containing the foam. In FIG. 6, the upper surface 72 of the bubble is shown by a solid line.

[0083] When the decompression of the internal space SP1 starts, the liquid contained in the food to be cooked is sucked toward the communication hole 412 due to the pressure difference between the internal space SP1 and the lid internal space SP2. Further, as the internal space SP1 is decompressed, the boiling point of the water contained in the food to be cooked rapidly decreases. As a result, the liquid present in the internal space SP1 is in a state of bumping where a large amount of bubbles are generated. As a result, as shown in FIG. 7, the upper surface of the liquid present in the internal space SP1 (for example, the upper surface 72 of the bubble) moves upward from the position before the decompression shown in FIG. 6.

[0084] As a result of the aforementioned suction and bumping boiling, at least a part of the liquid contained in the rice to be cooked enters the internal space SP2 of the lid body through the communication holes 412 as shown in FIG. 7. On the other hand, since the pressure in the internal space SP2 of the lid body is lower than the boiling pressure P2 (for example, atmospheric pressure), further upward movement of the liquid is suppressed. Thereby, the liquid that has entered the internal space SP2 of the lid body is stored in the storage portion 44.

[0085] Also, the rice contained in the rice to be cooked is sucked toward the communication holes 412 together with the liquid during decompression and moves upward in the internal space SP1. At this time, the rice contained in the rice to be cooked is in a state where gelatinization has progressed and has viscosity on the surface, and adheres to adjacent rice or the inner surface of the pot 2. Therefore, when the entire rice is pulled upward, as shown in FIG. 7, the upper surface 71 of the rice moves upward and the gap between the rice grains expands.

[0086] Also, due to the bumping boiling of the liquid caused by decompression, the water located in the gap between the rice grains greatly increases its volume during the process of vaporizing into steam and rapidly flows upward through the gap between the rice grains. Due to this flow of steam, the gap between the rice grains is further expanded.

[0087] During the decompression of the internal space SP1, the suction to the communication holes 412 and the bumping boiling in the internal space SP1 weaken as the pressure in the internal space SP1 approaches atmospheric pressure. Thereby, the moving speed of the liquid from the internal space SP1 to the storage portion 44 also decreases.

[0088] As shown in FIG. 3, after the start of decompression in the boiling maintenance step, the control unit 13 controls the pressure valve moving mechanism 63 to return the pressure valve 62 to the closed position again when the pressure in the internal space SP1 has dropped to atmospheric pressure or before that time. Thereby, the communication holes 412 are closed, and the decompression of the internal space SP1 in the boiling maintenance step ends.

[0089] Also, by closing the communication hole 412, it is possible to suppress the liquid (indicated by reference numeral 10 in FIG. 7) stored in the storage portion 44 from falling into the internal space SP1 by gravity through the communication hole 412. In the example shown in FIG. 3, when a predetermined time (e.g., 10 seconds) has elapsed after the communication hole 412 is opened, the control unit 13 moves the pressure valve 62 to the closed position. As a result, the communication hole 412 is closed, and the decompression of the internal space SP1 in the latter half of the boiling maintenance process ends. The decompression time T2 from the opening to the closing of the pressure valve 62 is, for example, 10 seconds.

[0090] After the decompression of the internal space SP1 starts, the control unit 13 may control the pressure valve moving mechanism 63 so as to maintain the pressure valve 62 in the communication position even after the pressure of the internal space SP1 has dropped to atmospheric pressure. Also in this case, the rice cooker is configured to hold the liquid stored in the storage portion 44 in the storage portion 44 until the end of the steaming process. For example, the upper opening of the communication hole 412 may be located above the upper surface 41a of the inner lid body 41. In this case, the liquid stored in the storage portion 44 cannot enter the communication hole 412 unless it moves upward above the upper opening of the communication hole 412 against gravity. Therefore, it is possible to suppress the liquid stored in the storage portion 44 from returning to the internal space SP1 through the open communication hole 412.

[0091] The boiling pressure P2 may be increased, for example, as the amount of the liquid desired to be stored in the storage portion 44 increases. That is, the control unit 13 may decompress the internal space SP1 from a higher boiling pressure P2 as the amount of the liquid desired to be stored increases. The amount of the liquid desired to be stored is, for example, an amount corresponding to the amount of rice contained in the object to be cooked or the amount of water contained in the object to be cooked. Also, the amount of the liquid desired to be stored may vary depending on the cooking sequence even if the amount of the object to be cooked is the same.

[0092] Due to the movement to the storage unit 44 under reduced pressure and the vaporization due to bumping boiling, in the internal space SP1 after the pressure reduction, most of the water contained in the rice to be cooked is lost. As a result, the temperature of the pot 2 can rise beyond the boiling point of water corresponding to the pressure of the internal space SP1, and it gets much closer to shifting to the steaming process. That is, the pressure reduction in the boiling maintenance process serves as a trigger for the shift from the boiling maintenance process to the steaming process. Therefore, in the boiling maintenance process, by advancing or delaying the timing of the pressure reduction, the length of the boiling maintenance process can be adjusted.

[0093] Also, after the pressure reduction, since the amount of water present in the internal space SP1 decreases, the rice in the pot 2 does not sink in the water after the pressure reduction in the boiling maintenance process. Therefore, the expanded gaps between the grains of rice are maintained even after the pressure reduction. As a result, fluffy cooked rice is achieved.

[0094] Note that the first half stage of the boiling maintenance process is all the time before half of the total boiling process time (it is not necessary to include from 19 minutes to 22 minutes and 30 seconds in FIG. 3, and it is sufficient to include a part of the time before the half). Also, the second half stage of the boiling maintenance process is all the time after half of the total boiling process time (it is not necessary to include from 22 minutes and 30 seconds to 26 minutes in FIG. 3, and it is sufficient to include a part of the time after the half). Different stages in the boiling maintenance process may intervene before the first half stage, between the first half stage and the second half stage, or after the second half stage. In the present embodiment, the first half stage corresponds to the time before half of the total time, and the second half stage corresponds to the time after half of the total time.

[0095] In the present embodiment, the second half stage starts after half of the total time of the boiling maintenance process. That is, the control unit 13 closes the pressure valve 62 and pressurizes the internal space SP1 to a boiling pressure P2 higher than the heating pressure P1 until at least half of the total time, and maintains the pressurized state of the internal space SP1. Also, the control unit 13 moves the pressure valve 62 to the communication position after half of the total time, and reduces the pressure of the internal space SP1 from the boiling pressure P2.

[0096] Further, when a predetermined time (for example, 60 seconds) has elapsed since the pressure in the internal space SP1 detected by the pressure detection unit 35 has risen to 1.5 atmospheres, the control unit 13 may move the pressure valve 62 to the communication position to decompress the internal space SP1 from the boiling pressure P2.

[0097] After the decompression in the boiling maintenance step ends, the control unit 13 controls the pressure valve moving mechanism 63 to maintain the pressure valve 62 in the closed position until the boiling maintenance step ends. As a result, the communication hole 412 is maintained in the closed state. On the other hand, since the heating of the pot 2 and the internal space SP1 by the heating unit 5 continues, the internal space SP1 is repressurized by the vaporization of the remaining water contained in the rice to be cooked.

[0098] When most of the water contained in the rice to be cooked is lost from the internal space SP1, the temperature of the bottom portion 21 of the pot 2 of the pot 2 can rise above the boiling point of water corresponding to the pressure in the internal space SP1. When it is detected that the detected temperature of the pot temperature sensor 12 has reached a predetermined temperature (for example, 130°C) above the boiling point, or when a predetermined time corresponding to the selected rice cooking course has elapsed since the start of the boiling maintenance step, the steaming step is entered. In the example shown in FIG. 3, at the time when 26 minutes have elapsed since the start of rice cooking, the detected temperature of the pot temperature sensor 12 has reached 130°C, and the process has shifted from the boiling maintenance step to the steaming step.

[0099] The steaming step is a step of evaporating excess moisture using residual heat and steaming the rice. The control unit 13 continuously controls the pressure valve moving mechanism 63 to maintain the pressure valve 62 in the closed position from the boiling maintenance step. The pressure in the internal space SP1 gradually decreases as the steam in the internal space SP1 condenses due to the temperature drop in the internal space SP1.

[0100] Further, the control unit 13 stops the heating operations of the inner bottom heating coil 51, the outer bottom heating coil 52, and the wall heating coil 53 that heat the pot 2 in the steaming step. Alternatively, the control unit 13 controls the heating amounts of the inner bottom heating coil 51, the outer bottom heating coil 52, and the wall heating coil 53 so as to maintain the temperature of the pot 2 at 100°C.

[0101] When a predetermined time has elapsed since the start of the steaming process or when the pressure in the internal space SP1 has dropped to a predetermined pressure, depressurization in the steaming process is performed. This depressurization is carried out to lower the pressure in the internal space SP1 to atmospheric pressure so that the lid can be safely opened after the cooking of rice is completed. Specifically, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the communication position.

[0102] As shown in FIG. 3, the control unit 13 gradually or gently decreases the pressure in the internal space SP1 from a pressure P3 that is lower than the boiling pressure P2 in the boiling maintenance process during the steaming process. In the present embodiment, the pressure P3 is 1.4 atmospheres. In the example shown in FIG. 3, at the time when 3 minutes and 30 seconds have elapsed since the start of the steaming process, the pressure in the internal space SP1 has dropped to the pressure P3, and the depressurization in the steaming process has started.

[0103] FIG. 8 is a diagram showing an enlarged part of the steaming process in FIG. 3. As shown in FIG. 8, in the present embodiment, the control unit 13 gradually decreases the pressure in the internal space SP1 by 0.1 atmosphere at a time. Specifically, after the control unit 13 moves the pressure valve 62 to the communication position, when the pressure in the internal space SP1 has dropped by 0.1 atmosphere from before the movement, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 back to the closed position. Then, after the control unit 13 maintains the pressure valve 62 in the closed position for a predetermined time, the control unit 13 controls the pressure valve moving mechanism 63 to move it back to the communication position again. When this operation is repeated three times, the pressure in the internal space SP1 drops to 1.1 atmospheres. Finally, the control unit 13 moves the pressure valve 62 to the communication position and controls the pressure valve moving mechanism 63 to depressurize the internal space SP1 to atmospheric pressure. When the pressure in the internal space SP1 drops to atmospheric pressure, the depressurization in the steaming process ends. At the same time, when the steaming process ends, all the rice cooking processes end.

[0104] The depressurization time T3 in the steaming process is longer than each of the depressurization time T1 (see FIG. 3) in the aforementioned heating-up process and the depressurization time T2 (see FIG. 3) in the boiling-maintaining process. Here, the depressurization time T3 is the time from when the internal space SP1 is depressurized to the pressure P3 and the communication hole 412 is opened until the pressure of the internal space SP1 drops to the atmospheric pressure. In the present embodiment, the depressurization time T3 in the steaming process is 30 seconds.

[0105] Further, the control unit 13 may gradually decrease the pressure in the internal space SP1 in the steaming process. For example, the control unit 13 may control the pressure valve moving mechanism 63 so as to move the pressure valve 62 to the communication position and gradually decrease the pressure in the internal space SP1 from 1.4 atmospheres to the atmospheric pressure over 240 seconds.

[0106] By gradually or stepwise decreasing the pressure in the internal space SP1, the eluate 8 adhering to the surface of the rice moves upward along with the air flow in the pot 2 accompanying the depressurization, and it is possible to suppress the uneven distribution at the upper part of the object to be cooked (cooked rice). Therefore, it is possible to suppress the stickiness generated at the upper part of the cooked rice.

[0107] After the rice cooking, in order to take out the cooked rice, the lid is opened to the open position by the user. FIG. 9 is a perspective view showing the inner lid of FIG. 2 when the lid is in the closed position and the open position. When the lid is in the closed position, the storage portion 44 and the liquid receiving portion 45 are located at substantially the same height in the vertical direction and are adjacent to each other in the front-rear direction. Therefore, in the lid internal space SP2, the liquid is stored straddling the inside of the storage portion 44 and the liquid receiving portion 45.

[0108] When the lid is opened toward the open position as indicated by the arrow in FIG. 9, the storage portion 44 moves upward relative to the liquid receiving portion 45. Further, the substantially disk-shaped inner lid body 41 is inclined such that the front portion 414 of the inner lid body 41 is positioned above the rear portion 415. As a result, the liquid stored in the storage portion 44 flows on the upper surface 41a of the inner lid body 41 and is accommodated in the liquid receiving portion 45 through the opening surface 451. Therefore, when the lid is opened, it is possible to prevent the liquid stored in the storage portion 44 from leaking to the outside of the lid.

[0109] According to the rice cooker according to the present embodiment, in the temperature rising step, the control unit 13 heats the pot 2 by the heating unit 5 with the pressure valve 62 closed, pressurizes the internal space SP1 to the rising temperature pressure P1, and then opens the pressure valve 62. When the pressure in the internal space SP1 decreases due to the opening of the pressure valve 62, the volume of the air in the bubble 9 remaining on the inner surface of the pot 2 increases. As a result, the bubble 9 is more likely to separate from the inner surface of the pot 2. The bubble 9 separated from the inner surface of the pot 2 rolls up the eluate 8 on the bottom portion 21 of the pot 2 and diffuses it into the water in the pot 2.

[0110] Further, when the air in the pot 2 is sucked through the communication hole 412, the object to be cooked rice is pulled upward. Along with the upward movement of the entire object to be cooked rice, the eluate 8 deposited on the bottom portion 21 of the pot 2 is pulled upward and diffused in the object to be cooked rice.

[0111] That is, by the upward movement of the bubble 9 in the water in the pot 2 and the upward movement of the object to be cooked rice accompanying the suction to the communication hole 412, the eluate 8 on the bottom portion 21 of the pot 2 can be diffused into the water in the pot 2. Thereby, in the temperature rising step in which the generation and precipitation of the eluate 8 start, it is possible to suppress the uneven distribution of the eluate 8 generated by the gelatinization of the rice.

[0112] By suppressing the uneven distribution of the eluate 8, it becomes difficult to hinder the convection in the object to be cooked rice and the heat conduction from the pot to the object to be cooked rice. Therefore, an improvement in the rate of increase in the temperature of the object to be cooked rice and a reduction in the temperature unevenness in the object to be cooked rice are realized. Therefore, the taste of the cooked rice is improved.

[0113] Particularly in the temperature-raising step, compared with the boiling-maintaining step, the amount of the eluate 8 is small and the degree of uneven distribution of the eluate 8 is also small. Further, since the amount of water reduced due to evaporation and water absorption of rice is small, the viscosity of the water in the pot 2 is low. Therefore, the depressurization in the temperature-raising step diffuses the eluate 8 more reliably in water than the depressurization in the subsequent steps. Further, compared with the case where depressurization is performed in a subsequent step, since the time during which the temperature unevenness of the object to be cooked is eliminated in the entire rice-cooking step (that is, the time from the depressurization from the temperature-raising pressure P1 to the end of rice cooking) is long, the taste of the cooked rice is further improved.

[0114] The control unit 13 changes the temperature-raising pressure P1 according to the amount of the object to be cooked and reduces the pressure of the internal space SP1 from the temperature-raising pressure P1 in the temperature-raising step. When the temperature-raising pressure P1 is changed, the pressure difference between the pressure of the internal space SP1 at the start of depressurization and the pressure outside the pot 2 (for example, the pressure of the internal space SP2 of the lid) changes. As a result, the amount of the bubbles 9 that leave the inner surface of the pot 2 and diffuse into the liquid in the pot 2 changes. Therefore, the intensity of stirring of the object to be cooked caused by depressurization is adjusted.

[0115] The larger the amount of the object to be cooked, the smaller the distance D1 between the water surface 73 in the pot 2 and the inner lid 4. Therefore, when depressurization is performed in the temperature-raising step in a state where the amount of the object to be cooked is large, the water in the pot 2 is sucked into the communication hole 412 and discharged to the outside of the pot 2. As a result, the water in the pot 2 may be insufficient in the steps after the temperature-raising step, and the taste of the cooked rice may deteriorate. For example, when the amount of water in the pot 2 decreases, the rice grains cannot be diffused separately in the boiling water, and the hardness of the cooked rice may vary. Further, when the amount of water in the pot 2 further decreases, the amount of heat applied to the rice may be insufficient, and the cooked rice may be cooked harder than the desired hardness.

[0116] On the one hand, according to the rice cooker according to this embodiment, the control unit 13 lowers the temperature-rising pressure P1 as the amount of the object to be cooked is larger, and reduces the pressure in the internal space SP1 from the temperature-rising pressure P1. Thereby, when the amount of the object to be cooked is large, the amount of water lost from the pot 2 can be reduced. Further, when the amount of the object to be cooked is small, since the pressure is reduced from a higher temperature-rising pressure P1 than when the amount of the object to be cooked is large, the eluate 8 can be more surely diffused in the object to be cooked. Therefore, even when the amount of the object to be cooked varies, the uneven distribution of the eluate 8 can be suppressed and the taste of the cooked rice can be improved.

[0117] Further, according to the rice cooker according to this embodiment, when the communication hole 412 is opened in the boiling maintenance step, the internal space SP1 is depressurized from the boiling pressure P2 higher than the atmospheric pressure. At this time, the liquid contained in the object to be cooked is sucked upward toward the communication hole 412 due to the pressure difference between the internal space SP1 and the internal space SP2 of the lid body. Further, since the boiling point of water in the internal space SP1 rapidly decreases as the pressure in the internal space SP1 decreases, the liquid contained in the object to be cooked is in a bumping boiling state. In the liquid in the bumping boiling state, vaporization proceeds rapidly, and a large amount of bubbles are generated, so that the upper surface of the liquid (for example, the upper surface 72 of the bubbles) rises. By the suction and the bumping boiling, a part of the liquid contained in the object to be cooked reaches the internal space SP2 of the lid body through the communication hole 412.

[0118] Further, in this embodiment, the pressure valve 62 closes the communication hole 412 when the internal space SP1 is depressurized to the atmospheric pressure or before that time. Thereby, since the liquid that has once reached the internal space SP2 of the lid body is suppressed from returning to the internal space SP1, the liquid is stored in the storage portion 44. Therefore, since a part of the liquid including the cooked rice soup can be collected in the storage portion 44, excessive adhesion of the cooked rice soup to the cooked rice can be suppressed.

[0119] Furthermore, since the liquid that has once reached the internal space of the lid does not return to the internal space SP1 until the end of the steaming process, the gaps between the rice grains (see Fig. 7) that have been expanded by the vaporization of the liquid during depressurization can be maintained in the expanded state. As a result, in the steaming process, the contact area between the rice grains becomes smaller, so each of the rice grains can be heated evenly. Therefore, the graininess and taste of the cooked rice are further improved.

[0120] When the food to be cooked contains glutinous rice or brown rice, the cooked food may change color or emit a peculiar odor due to the bran and lipids contained therein. According to the rice cooker according to the present embodiment, by recovering the liquid contained in the food to be cooked by depressurization in the boiling maintenance process, substances that cause discoloration and odor can be removed from the food to be cooked. Therefore, when the food to be cooked contains glutinous rice or brown rice, discoloration and odor of the cooked food can be reduced.

[0121] When the fluid communication between the storage unit 44 and the outside of the rice cooker is restricted, for example, when a valve is provided in the steam passage 33 that fluidly connects the storage unit 44 and the outside of the rice cooker, it is considered that the pressure in the storage unit 44 is higher than the atmospheric pressure during depressurization in the boiling maintenance process. In this case, the pressure difference between the internal space SP1 and the storage unit 44 is small, and there is a possibility that the liquid contained in the food to be cooked is not sufficiently sucked up to the internal space SP2 of the lid.

[0122] On the other hand, according to the rice cooker according to the present embodiment, since the storage unit 44 is in fluid communication with the outside of the rice cooker, the pressure in the storage unit 44 (that is, the pressure in the internal space SP2 of the lid) is the atmospheric pressure. As a result, compared with the above-described case, the pressure difference between the internal space SP1 and the storage unit 44 during depressurization becomes larger, and the suction force to the communication hole 412 increases. Therefore, the liquid contained in the food to be cooked can be more reliably sucked up to the internal space SP2 of the lid.

[0123] In addition, when the storage section 44 and the outside of the rice cooker are in fluid communication, if the pressure difference between the internal space SP1 and the outside of the pot 2 is large, there is a risk that the liquid contained in the rice to be cooked will be ejected to the outside of the rice cooker through the internal space SP2 of the lid during depressurization. On the other hand, in a configuration where the temperature rise pressure P1 is lowered as the amount of the rice to be cooked increases, during depressurization in the temperature rise process, the liquid contained in the rice to be cooked is suppressed from being discharged to the outside of the pot 2 (for example, the internal space SP2 of the lid). Therefore, even in a configuration where the storage section 44 and the outside of the rice cooker are in fluid communication, it is possible to suppress the liquid contained in the rice to be cooked from being ejected to the outside of the rice cooker.

[0124] Further, according to the rice cooker according to the present embodiment, the control unit 13 opens the pressure valve 62 in the latter half stage of the boiling maintenance process when the moisture in the pot 2 decreases, and reduces the pressure of the internal space SP1 from the boiling pressure P2. When depressurizing from the boiling pressure P2, since the water in the pot 2 is already in a state of being less, the water in the pot 2 is sucked into the communication hole 412 and is not easily discharged to the outside of the pot 2. Therefore, even without providing a large space for relaxing the momentum of water in the communication hole 412, it is possible to perform depressurization with a large pressure difference.

[0125] In addition, when the pressure difference of depressurization is large, bumping occurs due to the rapid decrease in the boiling point of the water in the pot 2. At this time, the water in the gaps between the grains of rice evaporates while increasing in volume, thereby expanding the gaps. Further, since depressurization is performed at a stage when the moisture in the pot 2 has decreased, after depressurization, there is little water remaining in the pot 2, and the rice does not sink in the water. Therefore, the gaps between the grains of rice are maintained in a state of being expanded by bumping. As a result, it is possible to achieve the cooking of fluffy rice. Therefore, it is possible to improve the taste of the rice while suppressing the increase in size of the rice cooker.

[0126] The higher the pressure of the internal space SP1, the higher the boiling point of the water in the pot 2. Therefore, assuming that heating is performed for the same amount of time, the higher the boiling pressure P2, the more heat can be applied to the rice before depressurization in the boiling maintenance process.

[0127] According to the rice cooker according to the present embodiment, in the boiling maintenance step, the control unit 13 increases the boiling pressure P2 as the cooking time is shorter, and decreases the pressure in the internal space SP1 from the boiling pressure P2. That is, when the cooking time is short, the boiling pressure P2 is increased, and when the cooking time is long, the boiling pressure P2 is decreased. Thereby, the same amount of heat can be applied to the rice even if the cooking time is different. Therefore, good cooking of rice can be achieved at various cooking times.

[0128] Further, according to the rice cooker according to the present embodiment, in the steaming step, the control unit 13 gradually or gently decreases the pressure in the internal space SP1. Thereby, it is possible to suppress the eluate 8 adhering to the surface of the rice from being sucked upward toward the communication hole 412 during the pressure reduction in the steaming step and being unevenly distributed on the upper part of the object to be cooked.

[0129] <Modification example> A modification example of the inner lid provided in the rice cooker according to the present embodiment will be described with reference to FIGS. 10 and 11. FIGS. 10 and 11 are perspective views showing a modification example of the inner lid provided in the rice cooker of FIG. 1. The inner lid 4A shown in FIGS. 10 and 11 is different from the inner lid 4 of the rice cooker according to the first embodiment in terms of the structure of the storage portion 44A.

[0130] As shown in FIGS. 10 and 11, the inner lid 4A has an inner lid body 41, a pot packing 42, and an outer lid packing 43A. As shown in FIG. 10, the outer lid packing 43A has an annular shape along the peripheral edge of the inner lid body 41 in a plan view of the inner lid 4A and protrudes upward. The diameter of the inner lid 4A is larger than the diameter of the inner lid 4 according to the first embodiment. When the inner lid 4A is used, the dimensions of the concave portion 321 (see FIG. 1) of the outer lid 3 in the left-right direction and the front-rear direction are set to dimensions such that the outer lid packing 43A can contact the inner wall surface of the concave portion 321.

[0131] As shown in FIG. 11, the inner lid 4A has a bottomed cylindrical storage portion 44A joined to the lower surface 41b of the inner lid body 41. The storage portion 44 has a bottom portion 441 and a wall portion 442 extending from the peripheral edge of the bottom portion 441 to the lower surface 41b of the inner lid body 41. In other words, the storage portion 44A has a concave shape that is recessed downward. The bottom portion 441 is located below the communication hole 412 when the lid body is in the closed position. In the present embodiment, the storage portion 44A is detachably joined to the inner lid body 41.

[0132] The wall portion 442 is provided with two joining recesses 443 for joining the storage portion 44 and the inner lid body 41. The two joining recesses 443 are provided at positions facing each other in a plan view of the inner lid 4 and are recessed toward the center of the storage portion 44A.

[0133] On the other hand, the inner lid body 41 has two joining walls 413 protruding downward. When the two joining walls 413 are fitted into the joining recesses 443 of the storage portion 44A, the storage portion 44A is joined to the inner lid body 41. At this time, the upper edge of the wall portion 442 is in close contact with the lower surface 41b of the inner lid body 41. That is, the upper opening of the storage portion 44A is sealed by the inner lid body 41. By making the storage portion 44A detachable from the inner lid body 41, it is possible to put a hand inside the storage portion 44A for washing, and the cleanability of the storage portion 44A is improved. Note that the storage portion 44A may be integrally formed with the inner lid body 41.

[0134] In the following description according to this modification, the description will be made assuming the state where the storage portion 44A is attached to the inner lid body 41. The broken line shown in FIG. 10 indicates the position of the upper edge of the wall portion 442. As shown in FIG. 10, the inner lid body 41 is provided with a hole portion 416 that fluidly communicates the inner space SP2 (see FIG. 1) of the lid body and the inside of the storage portion 44A. The inside of the storage portion 44A is in fluid communication with the outside of the storage portion 44A only through the hole portion 416. Therefore, the air pressure in the storage portion 44A becomes substantially the same as the air pressure in the inner space SP2 of the lid body.

[0135] In the present embodiment, the hole portion 416 is circular in a plan view of the inner lid 4, and one hole portion 416 is provided at the center of the inner lid main body 41. Further, in the plan view, the hole portion 416 is also located forward and closer to the center in the front-rear direction of the storage portion 44A. Further, in the present embodiment, the opening area of the hole portion 416 is smaller than the opening area of the communication hole 412.

[0136] The steam discharge hole 411, the communication hole 412, the pressure regulating valve 61, and the pressure valve 62 are located outside the storage portion 44A in a plan view of the inner lid 4.

[0137] When the internal space SP1 is depressurized from the boiling pressure P2, the liquid contained in the object to be cooked enters the lid internal space SP2 (see FIG. 1) through the opened communication hole 412 and reaches the upper surface 41a of the inner lid main body 41. When the liquid reaches the hole portion 416, the liquid falls inside the storage portion 44A by gravity through the hole portion 416. Thereby, the liquid contained in the object to be cooked is stored in the storage portion 44A.

[0138] In the inner lid 4A according to this modification, the communication hole 412 is located outside the storage portion 44A, and the bottom portion 441 of the storage portion 44A is located below the communication hole 412. Therefore, the liquid stored inside the storage portion 44A cannot reach the communication hole 412 unless it moves upward against gravity while the lid is in the closed position. Thereby, even when the communication hole 412 is maintained in an open state after the depressurization, it is possible to suppress the liquid stored in the storage portion 44A from returning to the internal space SP1. Therefore, regardless of the position of the pressure valve 62 after the depressurization, the liquid contained in the object to be cooked can be more reliably recovered into the storage portion 44A.

[0139] Further, the inside of the storage portion 44A is in fluid communication with the outside of the storage portion 44A only through the hole portion 416. Thereby, when the lid is opened after cooking, it is possible to suppress the liquid stored in the storage portion 44A from leaking to the outside of the storage portion 44A (for example, the lid internal space SP2).

[0140] <Second Embodiment> The rice cooker according to the second embodiment is different from the rice cooker according to the first embodiment in terms of the mode of changing the heating pressure P1 according to the amount of the object to be cooked.

[0141] In the rice cooker according to the second embodiment, the control unit 13 increases the heating pressure P1 as the amount of the object to be cooked increases, and reduces the pressure in the internal space SP1 from the heating pressure P1. For example, the control unit 13 sets the heating pressure P1 to 1.2 atmospheres when the amount of rice contained in the object to be cooked is 3 go, 1.3 atmospheres when it is 4 go, and 1.4 atmospheres when it is 5 go.

[0142] In a configuration where the pressure is reduced from a constant heating pressure regardless of the amount of the object to be cooked, when the amount of the object to be cooked is large, the stirring of the object to be cooked by the pressure reduction is weak, and the amount of bubbles 9 that leave the inner surface of the pot 2 and diffuse into the liquid in the pot 2 is small. As a result, the object to be cooked cannot be sufficiently stirred between the vicinity portion and the separated portion. Further, since the amount of the bubbles is small, the action of separating the rice grains adhered to each other in the vicinity portion is weak. Therefore, uneven heating in the object to be cooked cannot be sufficiently suppressed.

[0143] In order to more surely separate the rice grains from each other in the vicinity portion, it is conceivable to increase the number of times of pressure reduction in the heating process. However, when the number of times of pressure reduction increases, the time required for the heating process becomes longer, and the rice cooking time becomes longer. As a result, the convenience as a cooking appliance is reduced.

[0144] According to the rice cooker of the present embodiment, the control unit 13 increases the heating pressure P1 as the amount of the object to be cooked increases. When the heating pressure P1 increases, the pressure difference between the internal space SP1 and the outside of the pot 2 (for example, the internal space SP2 of the lid body) at the time of pressure reduction increases, and the amount of bubbles 9 that leave the inner surface of the pot 2 and diffuse into the liquid in the pot 2 increases. Thereby, even when the amount of the object to be cooked is large, the object to be cooked can be stirred with a strength sufficient to suppress uneven heating in the object to be cooked. Further, the adhesion between the rice grains in the vicinity portion can be more surely separated. Therefore, uneven heating in the object to be cooked can be more surely suppressed.

[0145] Furthermore, since the object to be cooked is sufficiently stirred regardless of the amount of the object to be cooked, it is possible to suppress the eluate 8 unevenly distributed on the contact region 2a from inhibiting the convection and heat conduction of the object to be cooked. As a result, in the process after the pressure reduction in the temperature rising process, the object to be cooked can be heated to a predetermined temperature more quickly. For example, after the pressure reduction in the temperature rising process, the time until the temperature of the water in the pot 2 reaches 100°C can be shortened. That is, the time of the temperature rising process can be shortened. Also, for example, in the boiling maintenance process, the time required to raise the temperature of the water in the pot 2 to near the boiling point corresponding to the pressure in the internal space SP1 can be shortened. Therefore, the time required for cooking can be shortened.

[0146] Note that the present disclosure is not limited to the above-described embodiment and can be implemented in various other modes. For example, in the above, it is assumed that the pressure reduction is performed in the boiling maintenance process, but the present disclosure is not limited thereto. For example, the pressure reduction from the boiling pressure P2 to the atmospheric pressure in the boiling maintenance process may not be performed.

[0147] FIG. 12 is a graph showing the operation of the rice cooker when the pressure reduction is not performed in the boiling maintenance process. In the example shown in FIG. 12, the control unit 13 controls the pressure valve moving mechanism 63 so as to maintain the pressure valve 62 in the communication position after the second pressure reduction (at the 26-minute time point in FIG. 12) in the temperature rising process. As a result, after the second pressure reduction, since the internal space SP1 and the outside of the rice cooker are in fluid communication, the pressure in the internal space SP1 is maintained at the atmospheric pressure. Note that, unlike the example shown in FIG. 12, the control unit 13 may control the pressure valve moving mechanism 63 so as to move the pressure valve back to the closed position after the second pressure reduction. In this case, the pressure in the internal space SP1 reaches 1.5 atmospheres at which the steam discharge hole 411 is opened in the boiling maintenance process, and may be maintained at 1.5 atmospheres by repeating the opening and closing of the steam discharge hole 411.

[0148] Further, in the above description, the communication hole 412 is opened only once during one pressure reduction in the temperature increasing process. However, the present disclosure is not limited thereto. For example, the control unit 13 may control the pressure valve moving mechanism 63 to repeatedly move the pressure valve 62 between the communication position and the blocking position during one pressure reduction in the temperature increasing process. In this case, the internal space SP1 is gradually depressurized from the temperature increasing pressure P1 to the atmospheric pressure during the one pressure reduction. That is, the pressure of the internal space SP1 gradually decreases during the one pressure reduction, similar to the pressure reduction in the steaming process (see FIG. 8). Thereby, during the pressure reduction in the temperature increasing process, it becomes difficult for the liquid contained in the object to be cooked to enter the communication hole 412, and the discharge of the liquid to the outside of the pot 2 can be further suppressed.

[0149] Further, in the above description, the pressure reduction in the temperature increasing process is performed twice. However, the present disclosure is not limited thereto. The pressure reduction in the temperature increasing process may be performed once or three or more times.

[0150] Further, in the above description, in the boiling maintenance process, when the temperature of the water in the pot 2 rises to near the boiling point corresponding to the pressure of the internal space SP1, the pressure valve 62 moves to the communication position. However, the present disclosure is not limited thereto. The timing at which the control unit 13 moves the pressure valve 62 to the communication position may be, for example, when a predetermined time has elapsed since the start of the boiling maintenance process, when the detected temperature of the pot temperature sensor 12 reaches a predetermined temperature, or when the detected pressure of the pressure detection unit 35 reaches a predetermined pressure. Further, the timing may be, for example, when the rising speed of the detected temperature of the pot temperature sensor 12 becomes a predetermined speed or more, or when the rising speed of the detected pressure of the pressure detection unit 35 becomes less than a predetermined speed.

[0151] Also, in the above description, in the steaming process, the control unit 13 gradually reduces the pressure in the internal space SP1 by 0.1 atm at a time. However, the present disclosure is not limited to this. For example, in the steaming process, the amount of pressure reduction per step in the internal space SP1 may be the same or different from each other. Also, the amount of pressure reduction may be greater than or less than 0.1 atm. Further, the control unit 13 may control the pressure valve 62 and the pressure valve moving mechanism 63 so as to repeatedly open and then close the communication hole 412 for a predetermined time. By this control as well, a stepwise pressure reduction in the internal space SP1 can be realized.

[0152] Also, in the above description, the storage portion 44 is configured as a part of the inner lid main body 41 and is flat. However, the present disclosure is not limited to this. For example, the storage portion 44 may be provided as a concave portion where a part of the inner lid main body 41 is recessed downward. At this time, in a plan view of the inner lid 4, the communication hole 412 may be located outside the storage portion 44. In this case, the liquid stored inside the storage portion 44 cannot reach the communication hole 412 unless it moves upward against gravity while the lid body is in the closed position. Thereby, even when the communication hole 412 remains open after the pressure reduction, it is possible to suppress the liquid stored in the storage portion 44 from returning to the internal space SP1.

[0153] Also, in the above description, the heating unit 5 is a coil that inductively heats the pot 2. However, for example, it may be an electric heater.

[0154] Also, in the above description, the temperature of the internal space SP1 is estimated based on the detected temperature of the pot temperature sensor 12. However, the present disclosure is not limited to this. For example, the rice cooker may be provided with a temperature detection sensor disposed between the outer lid 3 and the pot 2 instead of or in addition to the pot temperature sensor 12. In this case, the temperature of the internal space SP1 may be directly measured by the temperature detection sensor.

[0155] Further, in the above description, the pressure detection unit 35 is assumed to be a pressure sensor that directly measures the pressure in the internal space SP1. However, the present disclosure is not limited to this. For example, the pressure detection unit 35 may be a pressure estimation unit incorporated in the control unit 13 that estimates the pressure in the internal space SP1 based on the detected temperature of the pot temperature sensor 12 or the temperature detection sensor. In this case, the pressure estimation unit estimates the pressure in the internal space SP1 based on the saturated vapor pressure of water at various temperatures stored in the memory of the control unit 13 and the detected temperature.

[0156] FIG. 13 shows a saturated vapor pressure curve indicating the saturated vapor pressure of water at various temperatures. For example, when the temperature of the internal space SP1 detected by the pot temperature sensor 12 is 105°C, the pressure estimation unit estimates that the pressure in the internal space SP1 is approximately 1.2 atmospheres.

[0157] Also, in the modification of the first embodiment, the hole 416 is provided as one in the central portion of the inner lid body 41. However, the present disclosure is not limited to this. The hole 416 may be configured such that the liquid reaching the upper surface 41a of the inner lid body 41 easily falls inside the storage portion 44A. For example, the number of holes 416 may be two or more. The shape of the hole 416 in plan view is not limited to a circle, and may be an ellipse, a polygon, or the like. The position of the hole 416 in plan view is not limited to a position in front of the center in the front-rear direction of the storage portion 44A, and may be a position where the liquid reaching the lid body internal space SP2 through the communication hole 412 can reach. The opening area of the hole 416 may be larger than the opening area of the communication hole 412.

[0158] By appropriately combining any of the above-described various embodiments or modifications, the respective effects can be achieved. In addition, combinations of embodiments, combinations of examples, or combinations of an embodiment and an example are possible, and combinations of features from different embodiments or examples are also possible.

[0159] Although the present disclosure is fully described in connection with preferred embodiments with reference to the accompanying drawings, various modifications and variations will be apparent to those skilled in the art. Such modifications and variations are to be understood as being included therein as long as they do not depart from the scope of the present disclosure as defined by the appended claims.

Industrial Applicability

[0160] The present disclosure can suppress both uneven heating of rice and excessive adhesion of moisture to the rice, and thus is useful in a home or commercial rice cooker or a pressure cooker having a rice cooking function.

Explanation of Reference Numerals

[0161] 1 Rice cooker main body 1a Upper surface 2 Pot 2a Contact area 3 Outer lid 4, 4A Inner lid 5 Heating unit 8 Eluate 9 Bubble 10 Liquid 11 Pot storage section 12 Pot temperature sensor 13 Control unit 21 Pot bottom 22 Peripheral wall section 23 Flange section 31 Upper outer housing member 32 Lower outer housing member 33 Steam passage 34 Display operation section 35 Pressure detection section 41 Inner lid main body 41a Upper surface 41b Lower surface 42 Pot packing 43, 43A Outer lid packing 44, 44A Storage section 45 Liquid receiving section 51 Bottom inner heating coil 52 Bottom outer heating coil 53 Wall heating coil 54 Inner lid heating coil 61 Pressure regulating valve 62 Pressure valve 63 Pressure valve moving mechanism 71 Upper surface of the rice to be cooked 72 Upper surface of the bubbles 73 Water surface 111 Side wall part 112 Bottom part 321 Concave part 331 First opening end 332 Second opening end 411 Steam discharge hole 412 Communication hole 413 Joining wall 414 Front part 415 Rear part 416 Hole part 441 Bottom part 442 Wall part 443 Joining concave part 451 Opening surface 611 Closing member 612 Spring A1 Rotation axis SP1 Internal space SP2 Inner space of the lid

Claims

1. A pot for containing cooked rice ingredients including rice and water, A heating unit for heating the pot, A lid that can be opened and closed between a closed position closing the opening of the pot and an open position where the opening of the pot is opened, A pressure valve for opening and closing a communication hole communicating the internal space of the pot with the outside of the pot, A control unit for controlling the heating unit and the pressure valve, the control unit performing a rice cooking process including a temperature rising process of heating the pot by the heating unit until the temperature of the water reaches about 100°C, and a boiling maintaining process of boiling and maintaining the water after the temperature rising process, provided with, The control unit, In the temperature rising process, the pot is heated by the heating unit with the pressure valve closed, the internal space is pressurized to a temperature rising pressure higher than the atmospheric pressure, and then the pressure valve is opened to lower the pressure of the internal space from the temperature rising pressure, configured to change the temperature rising pressure according to the amount of the cooked rice ingredients and lower the pressure of the internal space from the temperature rising pressure, A rice cooker.

2. The control unit is configured to increase the temperature rising pressure as the amount of the cooked rice ingredients increases and lower the pressure of the internal space from the temperature rising pressure. The rice cooker according to claim 1.

3. The control unit is configured to lower the temperature rising pressure as the amount of the cooked rice ingredients increases and lower the pressure of the internal space from the temperature rising pressure. The rice cooker according to claim 1.

4. The lid has an outer lid and an inner lid attached to the outer lid and closing the opening of the pot when the lid is in the closed position, The inner lid is provided with the communication hole that fluidly communicates the internal space with the outside of the pot when the lid is in the closed position, The inner lid, The pressure valve controlled by the control unit and moving between a closed position for closing the communication hole and a communication position for opening the communication hole; A storage unit configured to store the liquid discharged from the internal space to the outside of the pot through the communication hole; having; The control unit executes a rice cooking process that further includes a steaming process of steaming the rice after the boiling maintenance process; In the boiling maintenance process, the control unit; While maintaining the pressure valve in the closed position, the pot is heated by the heating unit to pressurize the internal space to a boiling pressure higher than the atmospheric pressure; The pressure valve is moved to the communication position to depressurize the internal space from the boiling pressure, so that at least a part of the liquid contained in the object to be cooked is moved to the storage unit through the communication hole due to the pressure difference between the internal space and the outside of the pot; The liquid stored in the storage unit is configured to be stored in the storage unit until the end of the steaming process. The rice cooker according to claim 3.

5. The storage unit has a concave shape that is recessed downward when the lid is in the closed position; The communication hole is located above the bottom of the storage unit and outside the storage unit in a plan view of the inner lid when the lid is in the closed position; The rice cooker according to claim 4.

6. The storage unit is in fluid communication with the outside of the rice cooker. The rice cooker according to claim 4 or 5.

7. In the first half stage of the boiling maintenance process where there is sufficient moisture in the pot, the control unit closes the pressure valve to pressurize the internal space to a boiling pressure higher than the temperature rising pressure, and in the second half stage of the boiling maintenance process where the moisture in the pot decreases, the control unit opens the pressure valve to lower the pressure of the internal space from the boiling pressure, thereby expanding the gaps between the rice grains. The rice cooker according to claim 4 or 5.

8. further comprising a selection unit capable of selecting a cooking time, the control unit is configured to increase the boiling pressure as the cooking time selected by the selection unit is shorter in the boiling maintenance step, and to decrease the pressure in the internal space from the boiling pressure. The rice cooker according to claim 4 or 5.

9. the control unit executes a rice cooking process further including a steaming process of steaming the rice after the boiling maintenance process, the control unit is configured to close the pressure valve to pressurize the internal space after opening the pressure valve in the boiling maintenance process, and to gradually or gently decrease the pressure in the internal space in the steaming process. The rice cooker according to any one of claims 1 to 5.

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