Rice cooker

Abstract

To provide a rice cooker capable of reliably preventing an abnormal rise in pressure inside a pot.SOLUTION: A rice cooker comprises: a pot capable of accommodating cooking object rice; a body including a pot accommodating part capable of accommodating the pot; a lid body capable of opening and closing the pot accommodating part; an inner lid 61 detachably provided on the lid body, when the body is closed by the lid body, coming into contact with the pot to close the pot, and including a hole for connecting the inside and outside of the closed pot; a valve part 107 provided on the lid body and including a valve element that allows gas to flow between the inside and outside of the pot by opening the hole of the inner lid 61 and blocks the gas from flowing between the inside and outside of the pot by closing the hole of the inner lid 61; and a blocking prevention part 105 that protrudes through the hole to the inside of the pot whose inner lid 61 is closed, to prevent the cooking object rice from blocking the hole.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a rice cooker. [Background technology]

[0002] A rice cooker is known that is provided with a pressure regulating valve on the inside of the lid that adjusts the pressure inside the inner pot, and a safety valve that opens to reduce the pressure inside the inner pot if the pressure inside the inner pot increases abnormally. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-117989 Summary of the Invention [Problem to be solved by the invention]

[0004] The safety valve of a conventional rice cooker has a hole in the inner lid that corresponds to the valve seat and is covered by the valve body. If a foreign object, such as ingredients for seasoned rice in the inner pot, gets stuck in this hole in the inner lid, the safety valve may lose its function.

[0005] In conventional rice cookers, pressure regulators and safety devices have required a separate filter or other cover to prevent foreign matter from adhering to the valve exhaust pressure section during cooking, making the valve exhaust pressure section unblocked. The present invention provides a rice cooker in which a foreign matter prevention feature is directly attached to the valve, without the use of a separate part.

[0006] Therefore, an object of the present invention is to provide a rice cooker that can reliably prevent the pressure inside the pot from rising abnormally. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a rice cooker according to an embodiment of the present invention comprises a pot capable of accommodating the food to be cooked, a main body having a pot accommodating section capable of accommodating the pot, a lid capable of opening and closing the pot accommodating section, an inner lid that is detachably attached to the lid and closes the pot when the main body is closed with the lid, and has a hole connecting the inside and outside of the closed pot, a valve unit attached to the lid and having a valve body that allows gas to flow between the inside and outside of the pot by opening the hole in the inner lid and blocks the gas from flowing between the inside and outside of the pot by closing the hole in the inner lid, and a blockage prevention unit that protrudes through the hole into the inside of the pot when the inner lid is closed and prevents the food to be cooked from blocking the hole. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a rice cooker according to an embodiment of the present invention; [Figure 2] 1 is a vertical cross-sectional view of a rice cooker according to an embodiment of the present invention. [Figure 3] FIG. 2 is a cross-sectional view of the inner frame and heating coil of the rice cooker according to the embodiment. [Figure 4] FIG. 2 is a bottom view of the inner frame and heating coil of the rice cooker according to the embodiment. [Figure 5] FIG. 2 is a perspective view of the inner lid unit of the rice cooker according to the embodiment, seen from above, i.e., from the lid side. [Figure 6] 1 is a perspective view of the inner lid unit of the rice cooker according to the embodiment, seen from the bottom, i.e., the main body side. [Figure 7] FIG. 3 is an enlarged cross-sectional view of the lid gasket of the rice cooker according to the embodiment. [Figure 8] FIG. 3 is an enlarged cross-sectional view of the lid gasket of the rice cooker according to the embodiment. [Figure 9] FIG. 2 is a partial bottom view of the lid of the rice cooker according to the embodiment. [Figure 10] 1 is a perspective view of a rice cooker according to an embodiment of the present invention, showing a state in which the operation panel of the lid body and the outer lid are removed. FIG. [Figure 11] FIG. 2 is an enlarged cross-sectional view of a pressure regulating valve of the rice cooker according to the embodiment. [Figure 12]FIG. 2 is an enlarged cross-sectional view of the safety valve of the rice cooker according to the embodiment. [Figure 13] FIG. 3 is a perspective view of a gasket of a safety valve of the rice cooker according to the embodiment. [Figure 14] 4A and 4B are cross-sectional views of the lid gasket of the rice cooker according to the present embodiment, showing the behavior of the lid gasket when the lid is opened in time series. [Figure 15] FIG. 2 is a control block diagram of the rice cooker according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A rice cooker according to the present invention will be described below with reference to Figures 1 to 15. Note that the same or corresponding components are denoted by the same reference numerals throughout the drawings.

[0010] FIG. 1 is a perspective view of a rice cooker according to an embodiment of the present invention.

[0011] FIG. 2 is a vertical cross-sectional view of the rice cooker according to the embodiment of the present invention.

[0012] 1 is a perspective view of the rice cooker 1 according to this embodiment, viewed from diagonally above the front right. In other words, the front, right side, and top of the rice cooker 1 are visible in FIG. 2, while the back, left side, and bottom of the rice cooker 1 are hidden.

[0013] 1 and 2, rice cooker 1 according to this embodiment includes rectangular main body 23 having pot housing section 21 that opens upward, pot 25 housed in pot housing section 21, lid 26 that fits over the top of main body 23 to open and close pot housing section 21, hinge mechanism 27 that supports lid 26 on main body 23 so that it can be opened and closed, and a power line that can be connected to an external power source, such as a commercial AC power outlet. When lid 26 is opened upward on main body 23, pot 25 can be removed from pot housing section 21.

[0014] Rice cooker 1 heats and cooks rice and water contained in pot 25 using heating coil 31, and keeps the cooked rice warm by heating it using heating coil 31. Rice cooker 1 cooks the food using a cooking course that is selectively selected from a plurality of cooking courses.

[0015] Each cooking course has cooking conditions for cooking rice to rice. The cooking conditions include, for example, the type of rice, the cooking method for cooking the rice to rice, the hardness of the cooked rice, and the cooking time for cooking the rice to rice. Each cooking course includes at least two of these cooking conditions.

[0016] Each rice cooking course heats the food in pot 25 at a predetermined pressure. Each rice cooking course has processes that are set according to the brand of rice and the rice polishing ratio. Each process includes, for example, a soaking process that promotes the water absorption of rice placed in pot 25, a boiling and heating process that quickly raises the temperature of the food to the boiling point, a boiling continuation process that continues to boil the food, and a soaking process that maintains the temperature at a high enough temperature to prevent the rice from burning. Rice cooker 1 can also perform a warming process that keeps the rice in pot 25 at a predetermined warm temperature, either separately from the rice cooking course or consecutively to the rice cooking course.

[0017] Rice cooker 1 can also execute a cooking course that heats food other than the food placed in pot 25 using a predetermined heating pattern. Food includes the food to be cooked unless otherwise specified. Rice cooker 1 can also execute a maintenance course that boils water placed in pot 25 to use steam to lift dirt and remove odors from hard-to-clean parts inside rice cooker 1. For ease of explanation, the rice cooking course, cooking course, and maintenance course will hereinafter be collectively referred to simply as "courses."

[0018] Pot 25 is also called a "kettle." Pot 25 is a container with a bottom that holds water and rice to be cooked. Pot 25 has a main body 25a made of aluminum, which has high thermal conductivity, and a heating element 25b that is joined to the main body from the lower outer periphery to cover the bottom. The heating element is made of a magnetic metal plate made of ferritic stainless steel, for example. The inside of pot 25 is coated with a fluororesin. The fluororesin coating is formed by applying, for example, polytetrafluoroethylene (PTFE) or perfluoroalkoxy alkane (PFA). Pot 25 has a flange portion 32 that protrudes radially outward and surrounds the entire outer periphery.

[0019] The pot 25 is provided with a flange portion 32 that protrudes radially outward and surrounds the entire periphery of the outer periphery.

[0020] The planar shape of main body 23 is rectangular. Main body 23 defines the front, back, left side, right side, and bottom of rice cooker 1 below lid 26. Main body 23 includes a bottom plate 35 that defines the bottom surface of main body 23, an upper frame 36 that covers the top of bottom plate 35 and defines part of the top surface and the side surfaces of main body 23, a bowl-shaped inner frame 37 that is molded integrally with upper frame 36, and an outer frame 38 that defines the remainder of the top surface of main body 23.

[0021] The bottom plate 35, upper frame 36, and outer frame 38 form the outer shell of the main body 23. The bottom plate 35 and upper frame 36 are molded from synthetic resin, such as polypropylene (PP). The outer frame 38 is molded from a metal material, such as stainless steel.

[0022] Upper frame 36 and inner frame 37 define pot accommodating section 21. Inner frame 37 corresponds to the bottom plate of pot accommodating section 21. Inner frame 37 is a processed product made of, for example, aluminum-plated steel plate.

[0023] Pot accommodating section 21 accommodates pot 25 in a suspended state with the upper edge of pot accommodating section 21 in contact with the underside of flange 32 of pot 25. When pot 25 is accommodated in pot accommodating section 21, flange 32 of pot 25 and the upper edge of pot accommodating section 21 are in contact with each other with almost no gap between them, but flange 32 of pot 25 has a non-contact area along its circumference. This area defines a groove extending from the upper end of pot accommodating section 21 away from pot accommodating section 21. This groove creates a gap between pot accommodating section 21 and flange 32 of pot 25. This gap serves as a passageway for discharging steam generated between pot accommodating section 21 and pot 25 when pot 25 is heated with moisture adhering to its outer surface.

[0024] Main body 23 also has control unit housing chamber 39 defined between the outer casing and pot housing section 21. The outer casing of main body 23 has vent hole 41 that directs outside air into control unit housing chamber 39. Vent hole 41 is preferably located on the bottom or side of main body 23.

[0025] Furthermore, the main body 23 is equipped with a heating control circuit board 42 housed in the control unit housing chamber 39. The heating control circuit board 42 is equipped with a microprocessor and a storage device that stores digital information such as various calculation programs executed by the microprocessor, parameters, etc. The storage device stores various settings (arguments) related to multiple preset courses.

[0026] The main body 23 also includes a heat sink 43 attached to the microprocessor of the heating control circuit board 42 and a cooling fan 45 for blowing air onto the heat sink 43 .

[0027] The heat sink 43 is made of a material with good thermal conductivity, such as aluminum. The cooling fan 45 is located below or to the side of the heat sink 43. The cooling performance of the combined heat sink 43 and cooling fan 45 is set to maintain the temperature of the microprocessor within the operating temperature range. The cooling fan 45 and the vent 41 of the main body 23 are preferably positioned so that they sandwich the pot 25. This positioning relationship contributes to the miniaturization of the product.

[0028] Furthermore, the main body 23 is provided with a heating coil 31 provided on the outer surface of the inner frame 37 and a pot temperature sensor 46 provided in the center of the bottom surface of the inner frame 37 to detect the temperature of the bottom of the pot 25.

[0029] Heating coil 31 is arranged to face the lower outer circumferential surface and bottom surface of pot 25 housed in pot housing section 21. Heating coil 31 generates an alternating magnetic field to heat heating element 25b of pot 25 by electromagnetic induction.

[0030] Pot temperature sensor 46 passes through temperature sensor mounting hole 37a in the center of the bottom surface of inner frame 37 and comes into contact with the bottom surface of pot 25. Pot temperature sensor 46 has a thermistor that detects the temperature of the bottom of pot 25. The temperature of the bottom of pot 25 will hereinafter be referred to as the "pot bottom temperature." Pot temperature sensor 46 is pressed against the bottom surface of pot 25 by spring force. The pot bottom temperature detected by pot temperature sensor 46 is used primarily to control the heating temperature of pot 25 by heating coil 31.

[0031] Metal plate portion 48 has a groove portion that does not contact flange portion 32 over a portion of the circumferential range of flange portion 32 of pot 25. This groove portion extends from the upper end of pot accommodating portion 21 so as to be away from pot accommodating portion 21. This groove portion creates a gap between metal plate portion 48 and flange portion 32 of pot 25. This gap serves as a passage for discharging steam that is generated between pot accommodating portion 21 and pot 25 when pot 25 is heated with moisture adhering to its outer surface.

[0032] Hinge mechanism 27 includes hinge shaft 51 that swingably connects main body 23 and lid 26, and hinge spring 52 that applies a spring force to lid 26 so that lid 26, which closes pot housing section 21, opens upward on main body 23 around hinge shaft 51. Hinge shaft 51 is located near the upper part of the back surface of main body 23.

[0033] The planar shape of lid body 26 is a rectangle that covers main body 23. Lid body 26 defines the front, back, left side, right side, and top of rice cooker 1 above main body 23. Lid body 26 includes an outer lid 55 placed on the top of rice cooker 1, an outer lid cover 56 placed between outer lid 55 and main body 23, a metal heat sink 57 attached to outer lid cover 56, a lid heater 58 attached to heat sink 57, and an inner lid unit 59 detachably attached to outer lid cover 56 and detachably mounted below heat sink 57.

[0034] Outer lid 55 covers outer lid cover 56. When lid body 26 is closing main body 23, outer lid 55 covers and conceals outer lid cover 56 so that it is not exposed to the outside of rice cooker 1. Outer lid 55 has a recessed portion 55a that opens in a direction away from main body 23, in other words, that opens upward toward rice cooker 1, and a circuit board accommodating recess 55b provided within recessed portion 55a.

[0035] The outer lid cover 56 covers the main body 23 when the lid body 26 is closed on the main body 23.

[0036] The inner lid unit 59 comprises a metal inner lid 61 that is positioned below the heat sink 57 and in contact with the heat sink 57, a lid gasket 62 that is provided on the outer periphery of the inner lid 61, and a gasket base 63 that fixes the lid gasket 62 to the inner lid 61.

[0037] Heat sink 57 and inner lid 61 are formed from anodized aluminum or stainless steel plate material. Inner lid 61 corresponds to the bottom surface of lid body 26. Inner lid 61 has a disk shape with substantially the same diameter as the upper opening of pot 25.

[0038] Lid gasket 62 is, for example, a molded product made of silicone rubber or fluororubber. Lid gasket 62 is an annular sealing material that comes into contact with pot 25 and seals the gap between inner lid 61 and pot 25 when lid 26 is closed on main body 23. Lid gasket 62 comes into contact with the upper surface of flange 32 of pot 25 when lid 26 is closed.

[0039] When the lid body 26 with the inner lid unit 59 attached is closed, the lid gasket 62 contacts the flange portion 32 of the pot 25, and the inner lid unit 59 tightly covers the upper opening of the pot 25, sealing it so that steam generated when the pot 25 is heated does not leak between the pot 25 and the inner lid unit 59. For ease of explanation, the inside of the pot 25 closed by the inner lid unit 59 is referred to as the "pot internal space." The pot internal space is the space surrounded by the inner surface of the pot 25 and the bottom surface of the inner lid unit 59 and contains the food to be cooked. For ease of explanation, the pressure in the pot internal space will be referred to as the "internal pressure of the pot 25."

[0040] The lid heater 58 is, for example, a cord heater. The lid heater 58 heats the heat sink 57, thereby heating the inner lid 61 that is in contact with the heat sink 57.

[0041] The lid 26 also has a steam port 65 that is removably attached to the rear half of the upper surface of the lid 26 and discharges steam generated from the food being cooked in the pot 25 to the outside of the rice cooker 1, a steam exhaust path 66 that directs steam in the pot 25 to the steam port 65, and a pressure regulating valve 67 that allows or blocks the flow of gas in the steam exhaust path 66.

[0042] The steam discharge path 66 connects the steam port 65 and the pressure regulating valve 67. The steam discharge path 66 has an inlet-side labyrinth structure that is provided near the pressure regulating valve 67 and prevents steam from flowing linearly into the steam discharge path 66, and a discharge-side labyrinth structure that is provided near the steam port 65 and prevents steam from flowing linearly into the steam port 65.

[0043] Pressure regulating valve 67 is, for example, a solenoid valve. When pressure regulating valve 67 is opened, the inside of pot 25 is connected to the outside of rice cooker 1. At this time, pressure regulating valve 67 opens the inside of pot 25 to the atmosphere. Steam generated in pot 25 is released to the outside of rice cooker 1 through steam vent 65. When pressure regulating valve 67 is closed, the connection between the inside of pot 25 and the outside of rice cooker 1 is severed, restricting the flow of gas in and out through steam exhaust path 66. At this time, pressure regulating valve 67 seals the inside of pot 25. Steam generated in pot 25 increases the internal pressure of pot 25 above atmospheric pressure. The internal pressure of pot 25 can be reduced below atmospheric pressure by sucking out the gas inside pot 25 with pressure regulating valve 67 closed. The internal pressure of pot 25 can also be restored to atmospheric pressure by opening pressure regulating valve 67 while the internal pressure of pot 25 is reduced.

[0044] Pressure regulating valve 67 includes valve element 67a, which allows or blocks the flow of gas through steam exhaust passage 66, and valve element drive unit 67c, which includes solenoid 67b, which opens and closes valve element 67a. When steam in pot 25 is to be released to the outside of rice cooker 1, solenoid 67b moves valve element 67a in one direction to allow flow through steam exhaust passage 66. When the internal pressure of pot 25 is to be increased or decreased, solenoid 67b moves valve element 67a in the other direction to block flow through steam exhaust passage 66. When the food to be cooked in pot 25 boils, generating steam, and this steam fills pot 25, causing the internal pressure of pot 25 to exceed a predetermined value, valve element 67a is pushed up by the internal pressure of pot 25, opening steam exhaust passage 66. When the internal pressure of pot 25 falls below the predetermined value, valve element 67a closes steam exhaust passage 66. Such operation of valve body 67a maintains the internal pressure of pot 25 at or above atmospheric pressure.

[0045] Furthermore, the lid 26 is provided with a vacuum pump 68 that reduces the pressure inside the pot 25 when the lid 26 is closed.

[0046] The lid body 26 also includes a lid opening operation button 71 provided on the front half of the top surface of the lid body 26, a lid locking mechanism 72 that locks the opening and closing of the lid body 26, an operation panel 73 as an input / output device, and an input / output control circuit board 75 that controls the operation of the operation panel 73.

[0047] When lid-opening operation button 71 is operated, the lock between lid body 26, which closes pot accommodating section 21, and main body 23 is released. When lid body 26 and main body 23 are unlocked, the spring force of hinge spring 52 opens lid body 26 around hinge shaft 51 as the rotation center.

[0048] The lid locking mechanism 72 locks the lid 26 when the main body 23 is closed. The lid locking mechanism 72 unlocks the lid 26 in response to the operation of the lid-opening button 71. The lid locking mechanism 72 restricts the opening of the lid 26 even if the lid-opening button 71 is operated once if the internal pressure of the pot 25 is increased or decreased. If the lid-opening button 71 is operated again within a predetermined period of time, the lid locking mechanism 72 operates the pressure regulator valve 67 and the vacuum pump 68 to restore the internal pressure of the pot 25 to atmospheric pressure, and then releases the restriction on the opening of the lid 26. The lid locking operation of the lid locking mechanism 72 is controlled by the heating control circuit board 42. The detailed structure and control content of the lid locking mechanism 72 may be known technology, such as that described in JP 2015-171545 A. The lid locking operation of the lid locking mechanism 72 is not always performed. When the lid locking operation is not being performed, the lid 26 can be opened by operating the lid opening operation button 71 once.

[0049] Operation panel 73 is the top panel of lid 26 and rice cooker 1, and covers recessed portion 55a of outer lid 55. Operation panel 73 includes a display unit 76 that displays various information and an operation unit 77 that accepts various operations. Note that display unit 76 and operation unit 77 are essentially mounted on input / output control circuit board 75, and operation panel 73 includes a transparent window that allows the display on display unit 76 to be seen through, and key tops that correspond to a decorative panel that the user directly touches to operate operation unit 77.

[0050] The input / output control circuit board 75 is housed in the circuit board housing recess 55b of the outer lid 55 and is located directly below the operation panel 73. The input / output control circuit board 75 is equipped with a microprocessor, a memory device that stores digital information such as various calculation programs and parameters executed by the microprocessor, and a real-time clock (RTC) with a timekeeping function. The memory device stores various settings (arguments) related to multiple preset courses. The real-time clock functions as a clock that keeps track of the current time on the rice cooker 1 and as a timekeeping function. The real-time clock may be located on either the heating control circuit board 42 or the input / output control circuit board 75.

[0051] Display unit 76 is an output device that visually displays the current state of rice cooker 1. Display unit 76 is, for example, a display and a light-emitting diode (LED). The display is a liquid crystal display (LCD) panel or an organic electroluminescence (organic light-emitting diode) panel.

[0052] The operation unit 77 is an input device, a so-called touch sensor. The operation unit 77 is arranged directly above the display unit 76 so as to cover the display unit 76. The touch sensor has a plurality of key elements arranged on a plane. Each key element has a transparent electrode portion, for example, made of a conductive polymer, a contact portion connected to the input / output control circuit board 75, and pattern wiring connecting the transparent electrode portion and the contact portion. By pressing, touching, or bringing a fingertip against any of the display elements displayed on the display unit 76, the key element arranged directly above that display element is operated. The operation received by this key element is output to the input / output control circuit board 75 as a selection of the display element of the display unit 76 displayed directly below it.

[0053] A user of rice cooker 1 can select and input rice cooking conditions such as the type of rice, cooking method, hardness, and cooking time using operation unit 77. Based on the course set by operating operation unit 77, rice cooker 1 performs operations such as waiting for rice cooking, heating rice and water, keeping rice warm, and setting a timer for rice cooking.

[0054] It is assumed that a user of the rice cooker 1 will operate the operation panel 73 while standing in a position facing the front of the rice cooker 1. Therefore, the rice cooker 1 according to this embodiment is equipped with a lid-opening operation button 71 located in the front half of the top surface, closer to the user facing the front of the rice cooker 1, and a steam vent 65 located in the rear half of the top surface, farther from the user facing the front of the rice cooker 1. As a result, the rice cooker 1 according to this embodiment easily ensures a large space for arranging the display unit 76 between the lid-opening operation button 71 and the steam vent 65, and the size of the operation unit 77 located directly above the display unit 76 can be set as large as possible. Therefore, the rice cooker 1 can achieve high visibility of the display unit 76, high operability of the operation unit 77, and high safety against steam emitted from the steam vent 65.

[0055] Furthermore, the rice cooker 1 according to this embodiment does not have the physical operation keys found in conventional rice cookers, such as a rice cooker key and an off key, and can be operated using only the operation unit 77. Therefore, the rice cooker 1 according to this embodiment eliminates the need to search for the operation keys and provides intuitive operability. Furthermore, the rice cooker 1 without physical operation keys can integrate the display unit 76 and operation unit 77, improving space utilization efficiency and making it easier to design a much sleek exterior compared to conventional rice cookers in which the input and output devices are separated. Furthermore, the top surface of the rice cooker 1, which does not have physical operation keys, can be made flat with almost no irregularities or gently curved. The shape of the top surface of this rice cooker 1 makes it easy to clean, such as by wiping.

[0056] FIG. 3 is a cross-sectional view of the inner frame and heating coil of the rice cooker according to this embodiment.

[0057] FIG. 4 is a bottom view of the inner frame and heating coil of the rice cooker according to this embodiment.

[0058] As shown in FIGS. 3 and 4, the heating coil 31 of the rice cooker 1 according to this embodiment includes a plurality of coils 31u and 31d.

[0059] First coil 31u is provided on the outer surface of inner frame 37, and second coil 31d is provided on the outer bottom surface of inner frame 37. First coil 31u faces the lower part of the outer surface of pot 25 across inner frame 37. Second coil 31d faces the outer bottom surface of pot 25 across inner frame 37.

[0060] The transfer of heat when the heating coil 31 is energized will be described.

[0061] When the first coil 31u is energized, the lower portion of the outer surface of the pot 25 first heats up, and the heat from this portion is conducted to the main material 25a of the pot 25 and transferred to the water contained in the food that is in contact with the lower portion of the inner surface of the pot 25. Heat transfer within the food occurs primarily through water movement, i.e., convection. Where rice is present in the food, water movement is limited to the narrow gaps between the rice grains, slowing the movement of water and heat. Where rice is not present, the movement of water and heat, i.e., convection, becomes active. Therefore, after the water in contact with the lower portion of the inner surface, the water in the upper portion of the food first heats up. Because the rice grains sink to the bottom of the pot 25 due to their own weight, the upper portion of the food contains almost no rice grains and essentially only water. Subsequently, in the center of the food, the water and heat from the upper portion, which has become hot, move to the middle portion of the food, which is still cooler, and then to the lower portion of the food. This phenomenon is so-called thermal convection, and is called "external convection" due to the first coil 31u.

[0062] Furthermore, when second coil 31d is energized, the outer surface of the bottom of pot 25 heats up first, and the heat from this area is conducted to main material 25a of pot 25 and transferred to the inner surface of the bottom of pot 25, i.e., the water contained in the lower portion of the food that is in contact with the bottom. Because the rice grains sink to the bottom of pot 25 due to their own weight, the bottom of the pot is covered with rice and water contained in the lower portion of the food. Therefore, the heat from the bottom of the pot increases the temperature and pressure of the water covering the bottom of the pot. Then, the water at the bottom of the pot, whose temperature and pressure have increased, moves upward through the gaps between the rice grains contained in the food. In other words, the water heated in the lower portion of the food, i.e., the hot water, moves together with the heat to the middle portion of the food, and then to the upper portion of the food. This phenomenon is known as "blowing up" and is called "internal convection" caused by second coil 31d.

[0063] When current is alternately applied to first coil 31u and second coil 31d, external convection and internal convection alternately occur in the food to be cooked in pot 25. In other words, when current is alternately applied to first coil 31u and second coil 31d, the alternating external and internal convection promotes stirring of the water contained in the food to be cooked in pot 25, thereby reducing uneven heating of the food to be cooked.

[0064] The heating control circuit board 42 of the rice cooker 1 according to this embodiment operates the heating coil 31 in a plurality of current patterns that combine various current-carrying times of the first coil 31u, the second coil 31d, the output of the first coil 31u, and the output of the second coil 31d. These multiple current patterns are stored in the memory unit.

[0065] One type of energization pattern includes energizing the first coil 31u with a first output W1 and a first energization time T1, and then energizing the second coil 31d with a second output W2 and a second energization time T2. Each energization time T1 and T2 is preferably several seconds or longer. This allows external and internal convection to alternately occur in the food being cooked in the pot 25 for a predetermined period of time or longer. The alternating occurrence of external and internal convection promotes agitation of the water in the food being cooked in the pot 25 and reduces uneven heating.

[0066] It is preferable that the first current application time T1 and the second current application time T2 are different from each other. In other words, it is preferable that the time during which external convection occurs is different from the time during which internal convection occurs in a certain current application type.

[0067] The energization type may include one in which either the energization time or output of the heating coil 31 is varied while the other is kept constant. The energization time of each coil 31, 31d may be constant while the output of each coil 31, 31d may be different. Alternatively, the output of each coil 31, 31d may be constant while the energization time of each coil 31, 31d may be different.

[0068] The multiple energization patterns may include a de-energization period during which all of the heating coils 31 are de-energized. That is, the energization pattern is such that one of the two coils 31, 31d is energized for a predetermined energization time and with a predetermined output, and then, after a first de-energization period has elapsed, the other of the two coils 31, 31d is energized for a predetermined energization time and with a predetermined output, and then a second de-energization period is awaited. The first de-energization period and the second de-energization period may be the same or different.

[0069] The energization pattern may also include one in which current is intermittently applied to only one of the two coils 31, 31d, and no current is applied to the other of the two coils 31, 31d (no current is applied). Such an energization pattern applies current to one of the two coils 31, 31d for a predetermined current application time and at a predetermined current output, and does not apply current to both of the two coils 31, 31d for the predetermined current application time. Such an energization pattern is suitable for a heat retention process.

[0070] These current application patterns are repeated for a predetermined time or a predetermined number of times.

[0071] When the energization type is switched, the first energization type switches from energizing the first coil 31u with a first output W1 and a first energization time T1, and then energizing the second coil 31d with a second output W2 and a second energization time T2, to energizing the first coil 31u with a third output W3 and a third energization time T3, and then energizing the second coil 31d with a fourth output W4 and a fourth energization time T4. Each energization type is repeatedly executed for a predetermined time or a predetermined number of times before and after the switching.

[0072] The content of each energization type and the combination of multiple energization types are suitably set for each process included in the course.

[0073] In the energization type, the output of the first coil 31u and the output of the second coil 31d are adjusted by, for example, PWM control (Pulse Width Modulation).

[0074] Next, the lid body 26 will be described in detail. First, the inner lid unit 59 that closes the pot 25 will be described.

[0075] FIG. 5 is a perspective view of the inner lid unit of the rice cooker according to this embodiment, seen from above, that is, from the lid side.

[0076] FIG. 6 is a perspective view of the inner lid unit of the rice cooker according to this embodiment, as seen from the bottom, that is, from the main body side.

[0077] As shown in Figures 5 and 6, the inner lid 61 of the rice cooker 1 according to this embodiment is detachably attached to the lid body 26. When the lid body 26 is used to close the main body 23, the inner lid 61 closes the pot 25. The inner lid 61 has smooth upper and lower surfaces that are flat or have very gently curved surfaces in the areas that define the space inside the pot when the pot is closed. When the lid body 26 is used to close the main body 23, the lower surface of the inner lid 61 and the inner surface of the pot 25 cooperate to define the space inside the pot. The upper and lower surfaces of the inner lid 61 require cleaning during the rice cooking operation, but the flat upper and lower surfaces of the inner lid 61 are extremely easy to clean.

[0078] In addition, inner lid 61 has a plurality of holes that connect the space inside the pot with the space outside pot 25. The plurality of holes includes pressure adjustment hole 81 (second hole) that exhausts steam from the space inside the pot and allows atmosphere to flow into the space inside the pot, high-pressure exhaust hole 82 (first hole) that exhausts steam from the space inside the pot when the internal pressure of pot 25 exceeds a predetermined pressure, and pressure reduction hole 69 that is connected to pressure reduction pump 68 that exhausts gas from the space inside the pot and reduces the internal pressure of pot 25.

[0079] The pressure adjustment hole 81 and the high-pressure exhaust hole 82 correspond to the inlet of a steam exhaust path that discharges steam, and the steam port 65 corresponds to the outlet of the steam exhaust path.

[0080] The inner lid 61 has no irregularities on the upper or lower surface, including around the multiple holes, making it extremely easy to clean.

[0081] 7 and 8 are enlarged cross-sectional views of the lid gasket of the rice cooker according to this embodiment.

[0082] FIG. 7 is an enlarged cross-sectional view of the lid packing 62 in a free state with nothing touching it, and FIG. 8 is an enlarged cross-sectional view of the lid packing 62 pressed against the pot 25.

[0083] 7 and 8, the lid gasket 62 of the rice cooker 1 according to this embodiment is a one-piece molded product having a circular ring shape that follows the outer peripheral edge of the inner lid 61. The lid gasket 62 has a base 85 attached to the gasket base 63, an annular upper piece 86 extending from the base 85 radially outward of the inner lid unit 59, and a lower piece 87 extending from the base 85 downward of the inner lid unit 59.

[0084] Upper piece 86 and lower piece 87 are arranged to form an L-shape. When lid 26 is used to close main body 23, upper piece 86 comes into contact with the upper surface of flange 32 of pot 25. When lid 26 is used to close main body 23, lower piece 87 comes into contact with the inner surface of pot 25 or faces the inner surface of pot 25, facing each other.

[0085] The L-shape formed by the upper piece 86 and the lower piece 87 functions as a suction cup 88 that pushes gas out from the corner formed by the upper piece 86 and the lower piece 87, reducing the pressure and thereby attaching the lid gasket 62 to the pot 25.

[0086] Connection portion 89, which forms an L-shape between upper piece 86 and lower piece 87 and base 85, is thinner than other portions. Therefore, when force is applied to at least one of upper piece 86 and lower piece 87, upper piece 86 and lower piece 87, i.e., suction cup 88, behave as if they rotate together around connection portion 89. When a force that cannot be absorbed by the rotation of suction cup 88 around connection portion 89 acts on at least one of upper piece 86 and lower piece 87, suction cup 88 deforms so that the L-shape formed by upper piece 86 and lower piece 87 opens and closes. When the L-shape formed by upper piece 86 and lower piece 87 opens and gas is pushed out from the corner formed by upper piece 86 and lower piece 87, suction cup 88 adheres to pot 25. When the L-shape formed by the upper and lower pieces 86 and 87 opens and closes and gas flows into the corner formed by the upper and lower pieces 86 and 87, the suction cup portion 88 separates from the pot 25.

[0087] The upper piece portion 86 has a lower surface that contacts the flange portion 32 of the pot 25, an upper surface that does not contact the flange portion 32 of the pot 25, and an annular protrusion portion 91 provided on the upper surface and extending around the entire circumference of the upper piece portion 86.

[0088] The packing base 63 is an annular, one-piece molded product that follows the outer peripheral edge of the inner lid 61 and is positioned outside the lid packing 62. The packing base 63 has a recess 92 along the entire periphery at the outermost peripheral edge of its lower surface.

[0089] When no external force is applied to the upper piece portion 86, as shown in Figure 7, the upper piece portion 86 extends at a slight downward incline from the radially outer side of the inner lid unit 59. At this time, the lower piece portion 87 extends directly below the inner lid unit 59.

[0090] When closing the main body 23 with the lid 26, as shown in FIG. 8, the upper piece 86 first contacts the flange 32 of the pot 25, and the entire lid gasket 62 moves toward the pot 25. During this process, a force acts on the lid gasket 62 from the point of contact between the upper piece 86 and the flange 32. This force elastically deforms the connection portion 89 of the lid gasket 62, bringing the upper piece 86 closer to the gasket base 63 and tilting the upper piece 86 slightly upward toward the inner lid unit 59. As a result, the lower piece 87 tilts radially outward from the lid gasket 62 and presses against the inner surface of the pot 25. The gasket base 63 further presses the lid gasket 62, which behaves in this manner, toward the pot 25, causing the suction cup portion 88 to adhere airtightly to the pot 25.

[0091] When lid 26 is closed on main body 23, packing base 63 is separated from upper piece 86 and lower piece 87. In other words, while packing base 63 elastically supports suction cup 88 through base 85 of lid packing 62, when lid 26 is closed on main body 23, it does not come into contact with suction cup 88 as long as the internal pressure of pot 25 is atmospheric pressure or positive pressure.

[0092] When the lid 26 is closed on the main body 23 and the internal pressure of the pot 25 is reduced to a negative pressure, the negative pressure acting on the underside of the inner lid 61 draws the lid gasket 62 closer to the pot 25. At this time, the gasket base 63 approaches the flange 32 of the pot 25. The upper piece 86 of the lid gasket 62 is then sandwiched between the flange 32 of the pot 25 and the gasket base 63, while the annular protrusion 91 of the lid gasket 62 is caught in the recess 92 of the gasket base 63. At this time, the closest distance between the flange 32 of the pot 25 and the gasket base 63 is narrower than the thickness of the upper piece 86 of the lid gasket 62 and the annular protrusion 91. Therefore, the annular protrusion 91 cannot pass through the closest point between the flange 32 of the pot 25 and the gasket base 63 due to the pulling force caused by the assumed internal pressure of the pot 25. In this way, rice cooker 1 prevents lid gasket 62 from being pulled more than a predetermined amount inside pot 25. In other words, rice cooker 1 according to this embodiment does not prevent lid gasket 62 from being pulled inside pot 25 by tightly pinching upper piece 86 of lid gasket 62 between gasket base 63 and pot 25, but prevents lid gasket 62 from being pulled inside pot 25 by the engagement between annular protrusion 91 of lid gasket 62 and recess 92 of gasket base 63.

[0093] To open lid 26, first, lid-opening button 71 is operated to unlock the clamp that holds lid 26 closed on main body 23. This releases the spring force of hinge spring 52, which has been compressed in the direction to open lid 26. When this spring force overcomes the weight of lid 26 and the adhesive force of suction cup 88 attached to pot 25, suction cup 88 peels off from pot 25, and lid 26 is opened.

[0094] Next, the steam exhaust path that exhausts steam from inside pot 25 to the outside of rice cooker 1 will be described in detail. The steam exhaust path is a path that exhausts steam generated inside pot 25 to the outside of rice cooker 1, and also functions as an air intake path that allows the atmosphere inside rice cooker 1 to flow into pot 25 in order to restore the internal pressure of pot 25, which has been reduced by the decompression operation of vacuum pump 68, to atmospheric pressure. In other words, rice cooker 1 can pressurize or decompress the space inside the pot by blocking the flow of gas through the steam exhaust path, and can set the space inside the pot to essentially the pressure of the atmosphere, that is, atmospheric pressure, by allowing the flow of gas through the steam exhaust path.

[0095] Also, a decompression path for exhausting gas from inside the pot 25 to the outside of the rice cooker 1 to decompress the space inside the pot will be described.

[0096] FIG. 9 is a partial bottom view of the lid of the rice cooker according to this embodiment.

[0097] As shown in Figure 9, the lid body 26 of the rice cooker 1 of this embodiment is equipped with a steam exhaust passage 66, a pressure regulating gasket 95 surrounding the inlet side of the steam exhaust passage 66, a pressure regulating valve 67, a safety valve 97 that allows or blocks the flow of gas in the steam exhaust passage 66, a pressure reducing gasket 98 that airtightly connects a path leading to the pressure reducing pump 68 with the pressure reducing hole 69 of the inner lid 61, and an inner lid attachment sensor 99 that detects whether the inner lid unit 59 is attached to the lid body 26.

[0098] Steam exhaust path 66 and steam vent 65 are integrally molded with outer lid cover 56. The cross-sectional area of ​​steam exhaust path 66 is larger than the opening area of ​​pressure adjustment hole 81, larger than the opening area of ​​high-pressure exhaust hole 82, and larger than the opening area of ​​steam vent 65. In other words, steam exhaust path 66 expands the air path between pressure adjustment hole 81 and high-pressure exhaust hole 82, which are the inlets of the steam exhaust path, and steam vent 65, which is the outlet of the steam exhaust path.

[0099] When viewed from the bottom of the lid 26, the steam exhaust path 66 has a fan-shaped or trapezoidal planar shape that widens as it approaches the outside of the lid 26 from the center of the lid 26, and defines an open-air air passage that extends in the vertical direction (front-to-back direction) of the lid 26. The steam exhaust path 66 is open at the bottom of the lid 26. This shape of the steam exhaust path 66 reduces the occupancy rate of the steam exhaust path 66 in the central part of the lid 26 that houses various sensors including the inner lid attachment sensor 99 and devices such as the solenoid 67b that drives the pressure regulating valve 67, and increases the occupancy rate of the steam exhaust path 66 in the outer peripheral part of the lid 26 that houses relatively few parts and devices, thereby increasing the ratio of the volume of the steam exhaust path to the volume of the lid 26 and ensuring a necessary and sufficient volume for the steam exhaust path. The increased volume of steam exhaust channel 66 keeps the sticky substance that flows into steam exhaust channel 66 within steam exhaust channel 66, preventing the sticky substance from flowing out of rice cooker 1 through steam vent 65. In addition, the shape of steam exhaust channel 66 is suitable for a user to hold the cloth in their fingers for cleaning, and it also has a size (volume) suitable for cleaning.

[0100] When inner lid unit 59 is attached to lid body 26, pressure adjustment gasket 95 is pressed against the upper surface of inner lid 61, airtightly connecting pressure adjustment hole 81, high-pressure exhaust hole 82, and steam exhaust path 66. Pressure adjustment gasket 95 seals the gap between steam exhaust path 66 and the upper surface of inner lid 61 so that pressure adjustment valve 67 and safety valve 97 are contained within the steam exhaust path. Pressure adjustment gasket 95 guides steam from inside pot 25 flowing out from pressure adjustment hole 81 and high-pressure exhaust hole 82 to steam exhaust path 66, and also guides the atmosphere and outside air flowing in from steam vent 65 to pressure adjustment hole 81 and high-pressure exhaust hole 82. In other words, the space inside pressure adjustment gasket 95 is part of the steam exhaust path.

[0101] When inner lid unit 59 is attached to lid body 26, vacuum packing 98 is pressed against the upper surface of inner lid 61, airtightly connecting the path leading to vacuum pump 68 with vacuum hole 69. Vacuum packing 98 guides the gas in pot 25 that flows out from vacuum hole 69, which corresponds to the inlet of the vacuum path, to vacuum pump 68.

[0102] FIG. 10 is a perspective view of the rice cooker according to this embodiment, showing the state in which the operation panel of the lid body and the outer lid are removed.

[0103] As shown in FIG. 10 , the suction side of the pressure-reducing pump 68 of the rice cooker 1 according to this embodiment is connected to the pressure-reducing hole 69 of the inner lid 61 via a pressure-reducing gasket 98. The pressure-reducing pump 68 reduces the internal pressure of the pot 25 by discharging gas from the pot 25 through the pressure-reducing hole 69 to the outside of the rice cooker 1. To reduce the internal pressure of the pot 25, the pot 25 is placed in the pot housing 21, the lid 26 is closed, and the pressure-regulating valve 67 is closed. To restore the internal pressure of the pot 25 from a reduced pressure state to atmospheric pressure, the pressure-reducing pump 68 is stopped and the pressure-regulating valve 67 is opened. This connects the inside of the pot 25 to the outside of the rice cooker 1, allowing outside air to flow into the pot 25. The passage connecting the pressure-reducing pump 68 and the pressure-reducing hole 69 may be equipped with a pressure-reducing valve 70 that allows or blocks the flow of gas. The pressure-reducing valve 70 is preferably an electromagnetic valve that can be electrically controlled to open and close.

[0104] In other words, the pressure reducing pump 68 and the pressure adjusting valve 67 function as a pressure reducing section that can reduce the internal pressure of the pot 25 to a reduced pressure state lower than atmospheric pressure, and the pressure adjusting valve 67 also functions as a pressurizing section that can pressurize the internal pressure of the pot 25 to a pressurized state higher than atmospheric pressure.

[0105] FIG. 11 is an enlarged cross-sectional view of the pressure regulating valve of the rice cooker according to this embodiment.

[0106] 10 and 11, pressure adjustment valve 67 of rice cooker 1 according to this embodiment is a valve portion 107, also called a pressure control valve, provided in lid body 26. Pressure adjustment valve 67 includes valve body 67a that allows gas to pass between the inside and outside of pot 25 by opening pressure adjustment hole 81 in inner lid 61, and blocks gas from passing between the inside and outside of pot 25 by closing pressure adjustment hole 81 in inner lid 61.

[0107] The pressure regulating valve 67 has a solenoid 67b as a drive source for opening and closing the valve element 67a, thereby regulating the internal pressure of the pot 25 with the inner lid 61 closed. In addition to the valve element 67a and valve element drive unit 67c, the pressure regulating valve 67 also includes a valve stem 67d that elastically supports the valve element 67a and transmits the drive force generated by the valve element drive unit 67c to the valve element 67a, and a valve element support unit 67e that supports the valve element 67a and the valve stem 67d so that they can move back and forth. The pressure regulating valve 67 opens and closes the valve element 67a by reciprocating the valve stem 67d, which corresponds to the follower of the cam mechanism, using the valve element drive unit 67c, which corresponds to the driver of the cam mechanism. In other words, the pressure regulating valve 67 can open and close the pressure regulating hole 81 by reciprocating the valve stem 67d and the valve element 67a together when driven by the solenoid 67b. The pressure adjustment valve 67 can open and close the pressure adjustment hole 81 by elastically reciprocating the valve element 67a relative to the valve stem 67d.

[0108] The valve body 67a includes a valve body base 67aa having a cylindrical shape with a bottom, and a packing 67ab attached to the valve body base 67aa.

[0109] When the inner lid unit 59 is attached to the lid body 26, the packing 67ab faces the pressure adjustment hole 81 of the inner lid 61. The packing 67ab closes the pressure adjustment hole 81 by contacting the upper surface of the inner lid 61, which corresponds to the valve seat of the pressure adjustment valve 67, and opens the pressure adjustment hole 81 by moving away from the upper surface of the inner lid 61. The packing 67ab may have a flat shape that makes surface contact with the upper surface of the inner lid 61, or may have an annular protrusion that makes line contact with the upper surface of the inner lid 61 so as to surround the periphery of the pressure adjustment hole 81. The packing 67ab that makes line contact with the upper surface of the inner lid 61 so as to surround the periphery of the pressure adjustment hole 81 can reliably close the pressure adjustment hole 81 without making one-sided contact with the upper surface of the inner lid 61.

[0110] The valve stem 67d includes a follower 67da having a pair of opposing cam follower surfaces 67db, 67dc, and an elastic body 67dd connecting the valve element base 67aa to the follower 67da. The valve stem 67d elastically supports the valve element 67a via the elastic body 67dd.

[0111] The follower 67da has a pair of mountain-shaped cam follower surfaces 67db, 67dc that protrude in directions approaching each other.

[0112] In addition, the follower 67da supports the valve body base 67aa so that the valve body 67a can move independently in a direction approaching the pressure adjustment hole 81 relative to the follower 67da, and in a direction away from the pressure adjustment hole 81 relative to the follower 67da, i.e., so that the valve body 67a can move back and forth independently.

[0113] Furthermore, follower 67da holds valve element 67a so that it can move back and forth, with elastic body 67dd sandwiched between valve element base 67aa and follower 67da. That is, follower 67da and valve element base 67aa are connected by a slide mechanism that allows reciprocating motion while maintaining their unity and preventing them from coming apart. This slide mechanism includes a claw and a claw receiver that engage with each other, and a frame that determines the sliding direction.

[0114] The elastic body 67dd is sandwiched between the valve body base 67aa and the follower 67da in a state where a compressive load is applied so that the valve body 67a and the follower 67da move away from each other.

[0115] The valve element support portion 67e supports the valve element 67a and the valve stem 67d so that the valve element 67a and the valve stem 67d can move back and forth in a direction approaching the pressure adjustment hole 81 and a direction away from the pressure adjustment hole 81, that is, so that the valve element 67a and the valve stem 67d can move back and forth. The valve element support portion 67e is fixed to the outer lid cover 56.

[0116] The valve element drive unit 67c is provided on the outer lid cover 56. The valve element drive unit 67c includes a solenoid 67b and a frame 101 that is reciprocated by the solenoid 67b.

[0117] The frame 101 is equipped with a pressure regulating valve operating unit 102 that reciprocates the valve stem 67d and valve body 67a via a follower 67da, and a clamp operation regulating unit 103 that is part of the lid locking mechanism 72 and regulates or releases the restriction on the movement of the clamp that locks the lid body 26 that closes the main body 23.

[0118] The pressure regulating valve operating part 102 has a pair of cam surfaces 102a, 102b, each of which has a first straight portion far from the pressure regulating hole 81, a second straight portion close to the pressure regulating hole 81, and an inclined portion that is inclined with respect to the direction of reciprocating movement caused by driving of the solenoid 67b and connects the first straight portion and the second straight portion.

[0119] Here, the position where solenoid 67b pushes frame 101 out is referred to as the forward position (first position) of frame 101, and the position where solenoid 67b retracts frame 101 is referred to as the retracted position (second position) of frame 101. When frame 101 is moved to the forward position, the pair of cam surfaces 102a, 102b move follower 67da in a direction away from pressure adjustment hole 81, thereby opening pressure adjustment hole 81. When frame 101 is moved to the retracted position, the pair of cam surfaces 102a, 102b move follower 67da in a direction approaching pressure adjustment hole 81, thereby closing pressure adjustment hole 81.

[0120] The driving force for opening the pressure adjustment valve 67 is transmitted from the solenoid 67b to the valve stem 67d mainly by contact between the cam surface 102a, which is farthest from the pressure adjustment hole 81, and the cam follower surface 67db. The driving force for closing the pressure adjustment valve 67 is transmitted from the solenoid 67b to the valve stem 67d mainly by contact between the cam surface 102b, which is closer to the pressure adjustment hole 81, and the cam follower surface 67dc.

[0121] The distance between the first straight portion and the inner lid 61 and the distance between the second straight portion and the inner lid 61 correspond to the length and spring force of the elastic body 67dd to which a compressive load is applied so as to move the valve body 67a and the valve stem 67d apart. Note that the distance between the first straight portion and the inner lid 61 and the distance between the second straight portion and the inner lid 61 can also be set as the distance between the first straight portion and the second straight portion in the out-of-plane direction of the inner lid 61.

[0122] For example, when the frame 101 is in the forward position, the distance between the first straight portion and the inner lid 61 is set so that even if the internal pressure of the pot 25 acting on the gasket 67ab is in a reduced pressure state, such as from 0.8 atmospheres to 0.4 atmospheres, a force can be applied to the valve body 67a via the elastic body 67dd to move the gasket 67ab away from the inner lid 61 against the internal pressure of the pot 25.

[0123] The distance between the second straight section and the inner lid 61 is set so that when the frame 101 is in the retracted position and the internal pressure of the pot 25 acting on the gasket 67ab exceeds a set pressure, for example, 20 kilopascals (kPa), the gasket 67ab is pressed against the inner lid 61, closing the pressure adjustment hole 81. The distance between the second straight section and the inner lid 61 is set so that when the frame 101 is in the retracted position and the internal pressure of the pot 25 exceeds the set pressure, the valve element 67a is pushed up by the internal pressure of the pot 25 against the spring force acting from the elastic body 67dd, causing the gasket 67ab to move away from the inner lid 61 and open the pressure adjustment hole 81. The set pressure is also called the cracking pressure.

[0124] When the internal pressure of pot 25 is increased above atmospheric pressure, immediately after pressure adjustment valve 67 is opened, steam within pot 25 suddenly escapes through pressure adjustment hole 81. The faster the steam escapes, the greater the risk that foreign matter, such as ingredients for seasoned rice, will be drawn into and stick to pressure adjustment hole 81. Also, when the internal pressure of pot 25 is reduced below atmospheric pressure, immediately after pressure adjustment valve 67 is opened, gas suddenly flows into pot 25 through pressure adjustment hole 81 and is sprayed onto the food being cooked. The faster the gas escapes, the greater the risk that foreign matter, such as ingredients for seasoned rice, will be lifted up by the inflowing gas and stick to the inner surface of inner lid 61, hindering proper rice cooking. To reduce the outflow speed of steam and the inflow speed of gas, it is necessary to ensure a larger opening area for pressure adjustment hole 81.

[0125] On the other hand, when the internal pressure of pot 25 is reduced below atmospheric pressure, gasket 67ab of pressure adjustment valve 67 is sucked into pressure adjustment hole 81, blocking pressure adjustment hole 81. Considering the sealing properties of the valve, gasket 67ab is preferably made of a flexible material such as silicone rubber. However, the sealing surface of gasket 67ab made of such a material may be strongly adhered to the top surface of inner lid 61 due to the negative pressure inside pot 25, or may be deformed so that the central portion is strongly sucked into pressure adjustment hole 81 relative to the annular protrusion provided on the outer periphery of gasket 67ab to improve sealing properties.

[0126] In other words, if the opening area of ​​the pressure adjustment hole 81 is increased to reduce the outflow rate of steam and the inflow rate of gas, the force acting on the sealing surface of the packing 67ab during pressure reduction will become larger in proportion to the increased area of ​​the sealing surface, provided that the internal pressure per unit area is constant.

[0127] Therefore, pressure adjustment hole 81 is preferably a group of openings with multiple small holes 81a, as shown in Figures 5 and 6. For example, pressure adjustment hole 81 is a group of openings including two semicircular openings facing each other with a chord, and has a non-opening portion (cross-sectional position in Figure 11) spanning the center. The non-opening portion is preferably positioned near the centroid of packing 67ab, i.e., to inhibit deformation of the center of the sealing surface that moves closest to pressure adjustment hole 81 due to negative pressure within pot 25, thereby preventing packing 67ab from sticking to pressure adjustment hole 81. Such pressure adjustment hole 81 simultaneously reduces the outflow speed of steam and the inflow speed of gas and prevents the sealing surface from sticking when pressure is reduced.

[0128] FIG. 12 is an enlarged cross-sectional view of the safety valve of the rice cooker according to this embodiment.

[0129] 10 and 12, safety valve 97 of rice cooker 1 according to the present embodiment is valve portion 107 provided in lid body 26. Safety valve 97 includes valve body 97a that allows gas to pass between the inside and outside of pot 25 by opening high-pressure exhaust hole 82 in inner lid 61, and blocks gas from passing between the inside and outside of pot 25 by closing high-pressure exhaust hole 82 in inner lid 61.

[0130] The safety valve 97 opens the high-pressure exhaust port 82 when the internal pressure of the pot 25 exceeds a predetermined pressure. For example, if foreign matter adheres to the pressure adjustment port 81 and the internal pressure of the pot 25 exceeds the predetermined pressure, the safety valve 97 opens the high-pressure exhaust port 82 to lower the internal pressure of the pot 25. Preferably, the safety valve 97 closes the high-pressure exhaust port 82 and returns to its original position when the internal pressure of the pot 25 falls below the predetermined pressure. Therefore, the safety valve 97 includes a valve element holding cylindrical portion 97b provided on the outer lid cover 56 to define a cylindrical space, a valve lid portion 97c integrally provided on the valve element support portion 67e of the pressure adjustment valve 67 to close the valve element holding cylindrical portion 97b, a valve element 97a supported by the valve element holding cylindrical portion 97b and the valve lid portion 97c for reciprocating movement, and an elastic body 97d interposed between the valve element holding cylindrical portion 97b and the valve element 97a to generate a force pressing the valve element 97a against the top surface of the inner lid 61.

[0131] The valve body 97a opens the high-pressure exhaust hole 82 when the internal pressure of the pot 25 with the inner lid 61 closed exceeds a predetermined pressure. The valve body 97a includes a valve body base 97aa supported by a valve body holding cylindrical portion 97b so as to be capable of reciprocating motion, and a gasket 97ab provided at the tip of the valve body base 97aa.

[0132] The elastic body 97d is, for example, a coil spring.

[0133] FIG. 13 is a perspective view of the packing of the safety valve of the rice cooker according to this embodiment.

[0134] 12 and 13, when the inner lid unit 59 is attached to the lid body 26, the gasket 97ab of the safety valve 97 of the rice cooker 1 according to this embodiment comes into contact with the upper surface of the inner lid 61 to close the high-pressure exhaust hole 82. The gasket 97ab may have a flat shape that makes surface contact with the upper surface of the inner lid 61, or it may have an annular protrusion that makes line contact with the upper surface of the inner lid 61 so as to surround the periphery of the high-pressure exhaust hole 82. The gasket 97ab that makes line contact with the upper surface of the inner lid 61 so as to surround the periphery of the high-pressure exhaust hole 82 can reliably close the high-pressure exhaust hole 82 without making partial contact with the upper surface of the inner lid 61.

[0135] High-pressure exhaust hole 82 is connected to steam exhaust passage 66, similar to pressure adjustment hole 81. Gas flowing out of the space inside the pot through high-pressure exhaust hole 82 passes through steam exhaust passage 66 and is exhausted from steam port 65.

[0136] High-pressure exhaust hole 82 is preferably located away from pressure adjustment hole 81. In other words, safety valve 97, which opens and closes high-pressure exhaust hole 82, is also preferably located away from pressure adjustment valve 67. This reduces the risk of both pressure adjustment hole 81 and high-pressure exhaust hole 82 being blocked simultaneously by foreign matter such as sticky rice or ingredients for mixed rice.

[0137] If pressure adjustment hole 81 becomes clogged with foreign matter or solenoid 67b malfunctions, pressure adjustment valve 67 will lose its ability to open pressure adjustment hole 81. If the internal pressure of pot 25 then reaches an abnormal pressure (predetermined pressure) equal to or greater than the set pressure, safety valve 97 will open high-pressure exhaust hole 82. The predetermined pressure at which safety valve 97 opens high-pressure exhaust hole 82 is, for example, 26 kilopascals, which is set higher than the set pressure at which pressure adjustment valve 67 opens pressure adjustment hole 81, for example, 20 kilopascals. Therefore, if an abnormality occurs in the exhaust of steam through pressure adjustment hole 81 and the internal pressure of pot 25 reaches an abnormal pressure, safety valve 97 will open high-pressure exhaust hole 82.

[0138] However, if the high-pressure exhaust hole 82 is blocked by a foreign object, the safety valve 97 may lose its function. If both the pressure adjustment hole 81 and the safety valve 97 fail simultaneously, the internal pressure of the pot 25 may become higher than expected. Therefore, even if both the pressure adjustment hole 81 and the safety valve 97 fail simultaneously, the lid gasket 62 of the inner lid unit 59 functions as a safety device to release the internal pressure of the pot 25. However, even if the lid gasket 62 functions to release the internal pressure of the pot 25, it will remain in a state that releases the internal pressure of the pot 25 and will not automatically return to a state that closes the internal space of the pot. If this happens, the rice cooker 1 may not be able to control the internal pressure of the pot 25 and may not be able to perform proper rice cooking operations.

[0139] Therefore, the rice cooker 1 of this embodiment is equipped with a blockage prevention portion 105 that protrudes through the high-pressure exhaust hole 82 to the inside of the pot 25 when the inner lid 61 is closed, and prevents the food being cooked as a foreign object from blocking the high-pressure exhaust hole 82.

[0140] Immediately after safety valve 97 opens high-pressure exhaust hole 82, steam inside pot 25 rapidly flows toward high-pressure exhaust hole 82. This rapid flow of steam may cause the food to be cooked as foreign matter to be swirled up toward high-pressure exhaust hole 82. Therefore, it is preferable that clogging prevention part 105 protrudes through high-pressure exhaust hole 82 to the inside of pot 25 with inner lid 61 closed, so that clogging of high-pressure exhaust hole 82 can be prevented whether safety valve 97 opens or closes high-pressure exhaust hole 82.

[0141] Note that as long as clog prevention portion 105 can prevent high-pressure exhaust hole 82 from being blocked when safety valve 97 opens high-pressure exhaust hole 82, the function of safety valve 97 will not be impaired. In other words, when safety valve 97 closes high-pressure exhaust hole 82, the function of safety valve 97 may not be lost regardless of whether or not a foreign object blocks high-pressure exhaust hole 82. Therefore, clog prevention portion 105 may protrude through high-pressure exhaust hole 82 to the inside of pot 25 with inner lid 61 closed only when safety valve 97 opens high-pressure exhaust hole 82.

[0142] The clog prevention portion 105 is provided on the valve disc 97a of the safety valve 97. The clog prevention portion 105 is preferably integrally molded with the packing 97ab of the valve disc 97a. The clog prevention portion 105 may also be provided on the valve disc base 97aa of the valve disc 97a and penetrate the packing 97ab. The clog prevention portion 105 integrally molded on the valve disc 97a reduces the structural complexity of the safety valve 97 and prevents a decrease in the reliability of the opening and closing operation of the safety valve 97 and the shutoff performance of the safety valve 97. The clog prevention portion 105 may also be provided on the valve disc holding cylindrical portion 97b and penetrate the entire valve disc 97a. In other words, the clog prevention portion 105 may be integrated with the valve disc 97a so as to follow the reciprocating movement of the valve disc 97a, or it may be a non-moving, i.e., fixed, portion provided in a location corresponding to the valve body of the safety valve 97 and not follow the valve disc 97a.

[0143] Typically, the inner lid unit 59 is attached to the lid body 26 along an arc-shaped path that approaches zero degrees around a fulcrum located near the hinge mechanism 27 of the lid body 26 and where the recessed and projecting parts fit together. Therefore, the occlusion prevention portion 105 preferably has a tapered shape that narrows toward the protruding end 105a. A occlusion prevention portion 105 of this shape can smoothly reach the interior of the pot through the high-pressure exhaust hole 82 without contacting the edge of the opening of the high-pressure exhaust hole 82, and can ensure a longer protruding length within the interior of the pot. If the occlusion prevention portion 105 were a cylinder with the same diameter as the opening of the high-pressure exhaust hole 82, the inner lid unit 59 would have to be moved linearly relative to the lid body 26 to be attached, and the occlusion prevention portion 105 would block the high-pressure exhaust hole 82, causing the safety valve 97 to lose its function. Therefore, the tapered occlusion prevention portion 105 is an extremely effective shape.

[0144] The clogging prevention portion 105 also has a hemispherical protruding end 105a that is positioned within the pot interior. The clogging prevention portion 105 is exposed to high-temperature steam when the rice cooker 1 is operating in a rice cooking mode. Therefore, by rounding the protruding end 105a of the clogging prevention portion 105 into a hemispherical shape, for example, a hemispherical shape with a diameter of approximately 1 millimeter, thermal deterioration of the clogging prevention portion 105 can be suppressed. For example, if the clogging prevention portion 105 is integrally molded with the packing 97ab, the clogging prevention portion 105 can be integrally molded from the same material as the packing 97ab. The packing 97ab is generally made from rubber or a silicone resin with rubber-like properties, commonly known as silicone rubber. Therefore, by rounding the protruding end 105a of the clogging prevention portion 105 into a hemispherical shape, thermal deterioration can be suppressed. The same applies when the clogging prevention portion 105 is integrally molded with the synthetic resin lid 26. Furthermore, when lid body 26 is opened, protruding end 105a of closure prevention portion 105 is exposed to inner lid 61, which the user can see together with the opening of pot 25. It is also preferable from the viewpoint of appearance to round off the sharp edges of such portions.

[0145] The rice cooker 1 is equipped with multiple valve units 107, namely, a safety valve 97 and a pressure regulating valve 67. If the safety valve 97 is provided with a clog prevention unit 105, the risk of the rice cooker 1 losing its function of controlling the internal pressure of the pot 25 is extremely low. However, the rice cooker 1 may also be equipped with a clog prevention unit 105 in the pressure regulating valve 67. This increases the likelihood that the rice cooker 1 will perform a satisfactory rice cooking operation.

[0146] Rice cooker 1 can reduce the internal pressure of pot 25 to below atmospheric pressure by opening pressure-reducing valve 70 while pressure-regulating valve 67 and safety valve 97 are closed, i.e., while steam exhaust path 66 is closed, and by starting the pressure-reducing operation of pressure-reducing pump 68. If the internal pressure of pot 25 drops to a negative pressure below atmospheric pressure, pressure-regulating valve 67 and safety valve 97 are closed by the negative pressure within pot 25, and by closing pressure-reducing valve 70, the internal pressure of pot 25 can be maintained at a reduced pressure even when the pressure-reducing operation of pressure-reducing pump 68 is stopped. Furthermore, when the internal pressure of pot 25 is at a reduced pressure, the internal pressure of pot 25 can be restored to atmospheric pressure by closing pressure-reducing valve 70, stopping the pressure-reducing operation of pressure-reducing pump 68, and opening pressure-regulating valve 67.

[0147] Incidentally, when the keep-warm step is performed, the internal pressure of pot 25 may be reduced. When opening lid 26 in a reduced-pressure state, pressure regulator valve 67 is opened to restore the internal pressure of pot 25 to atmospheric pressure. This significantly reduces the force required to open closed lid 26. The keep-warm step performed following the rice cooking operation and the keep-warm step performed independently are collectively referred to as the "keep-warm operation."

[0148] However, if the keep-warm operation continues under reduced pressure for a long period of time, lid gasket 62 will be pressed firmly against flange 32 of pot 25, causing suction cup 88 of lid gasket 62 to tightly adhere to pot 25. If this happens, lid gasket 62 may not easily separate from flange 32 of pot 25 even when the internal pressure of pot 25 is restored to atmospheric pressure.

[0149] FIG. 14 is a cross-sectional view of the lid gasket of the rice cooker according to the present embodiment, showing the behavior of the lid gasket in time series when the lid is opened.

[0150] 6 and 14, the lid gasket 62 of the rice cooker 1 according to this embodiment has a suction cup 88 that is pressed against and adheres to the pot 25 when the main body 23 is closed with the lid 26, and a protrusion 111 that is part of the adhesion surface of the suction cup 88 and is provided on the opposite side of the center of the hinge mechanism 27 and the inner lid 61. In the rice cooker 1 according to this embodiment, the protrusion 111 is provided 180 degrees away from the hinge mechanism 27 and in a position farthest from the hinge mechanism 27, but this is not a limitation and it may be provided on the opposite side of the center of the inner lid 61.

[0151] As shown in Figure 14(a), when suction cup portion 88 is pressed against pot 25, gas is pushed out from the corner of the L-shape formed by upper piece portion 86 and lower piece portion 87, causing suction cup portion 88 to adhere to pot 25. The space surrounded by the L-shape formed by upper piece portion 86 and lower piece portion 87 and pot 25, where the air is pushed out and a force that adheres suction cup portion 88 to pot 25, is conveniently referred to as suction space 112. Suction space 112 is defined by the lower surface of upper piece portion 86, the outer peripheral surface of lower piece portion 87, the inner surface of pot 25, and the upper surface of flange portion 32. The lower surface of upper piece portion 86 and the outer peripheral surface of lower piece portion 87 are the attachment surfaces of suction cup portion 88.

[0152] When the lid body 26 is opened, as shown in Figure 14(b), the inner lid unit 59 begins to move away from the pot 25. Then, as shown in Figure 14(c), when the protrusion 111 reaches the suction space 112, gas flows into the suction space 112, and the force that attaches the suction cup portion 88 to the pot 25 is reduced and lost.

[0153] Therefore, the protrusion 111 is provided on the outer periphery of the lower surface of the upper piece portion 86 and extends in the radial direction of the lid gasket 62. In other words, the inner periphery of the lower surface of the upper piece portion 86 does not have the protrusion 111 and functions as part of the wall that defines the suction space 112. Specifically, in the radial direction of the lid gasket 62, the total length of the protrusion 111 is shorter than the width of the upper piece portion 86, that is, half the difference between the inner diameter and the outer diameter of the upper piece portion 86. This ensures that the inner periphery of the upper piece portion 86 has a shape that is necessary and sufficient to function as part of the wall that defines the suction space 112.

[0154] On the other hand, when opening the lid 26, the spring force of the hinge spring 52 acts on the suction cup 88 via the base 85 of the lid gasket 62. This spring force acts to separate the suction cup 88 from the pot 25. If the suction cup 88 is tightly attached to the pot 25, the spring force of the hinge spring 52 may counteract the weight of the lid 26 and the adhesive force of the suction cup 88 attached to the pot 25. In this case, as shown in Figures 14(b) to 14(d), it takes time for the upper and lower pieces 86 and 87 to deform into an L-shape during the process of separating the suction cup 88 from the pot 25, and for gas to be introduced into the suction space 112 as a result of this deformation, i.e., for the negative pressure to be restored. This time lengthens the time it takes to open the lid 26.

[0155] 14(c), the convex portion 111 connects the inner peripheral end of the convex portion 111, which is located inside the outer peripheral edge of the upper piece 86, to the suction space 112 before the L-shaped deformation formed by the upper piece 86 and the lower piece 87 progresses significantly, i.e., before the suction space 112 reaches the outer peripheral edge of the upper piece 86. When the suction space 112 reaches the inner peripheral end of the convex portion 111, the introduction of gas into the suction space 112, i.e., the recovery of negative pressure, is promoted, and the lid 26 is quickly opened. It can be easily understood that when the suction space 112 reaches the inner peripheral end of the convex portion 111 due to the L-shaped deformation formed by the upper piece 86 and the lower piece 87, both side surfaces of the convex portion 111 in the circumferential direction of the lid gasket 62 become passages for introducing gas into the suction space 112.

[0156] The protrusion 111 has a substantially semicircular cross-sectional shape when viewed in the radial direction of the lid gasket 62. The semicircular protrusion 111 defines a space that opens at an obtuse angle when viewed in the radial direction of the lid gasket 62 at the boundary between the protrusion 111 and the suction surface, i.e., at the base of the protrusion 111. This obtuse-angled space opens more widely than, for example, a rectangular protrusion 111. Such an obtuse-angled space is more easily crushed than a right-angled space that opens at the base of the rectangular protrusion 111 when the upper piece 86 is pressed against the flange 32 of the lid 26 and gas is expelled from the suction space 112. Therefore, the semicircular protrusion 111 does not prevent the suction cup 88 from adhering to the pot 25. On the other hand, when the adsorption space 112 reaches the inner peripheral end of the protrusion 111, the semicircular protrusion 111 opens a passage with a larger cross-sectional area than the right-angled space opening at the base of the rectangular protrusion 111, and quickly introduces gas into the adsorption space 112.

[0157] The lid packing 62 may have cutouts such as slit-shaped portions, semicircular groove-shaped portions, triangular groove-shaped portions, or polygonal groove-shaped portions instead of or in addition to the protrusions 111. These cutouts and protrusions 111 function as pressure recovery paths that restore the negative pressure in the suction space 112 of the suction cup portion 88 to atmospheric pressure.

[0158] Conventional rice cookers include a packing base with an annular rib that presses the first seal against the flange of the pot, sandwiching the first seal between the flange and the packing base. When negative pressure acts on the inner lid, the annular rib of the packing base presses the first seal against the flange of the pot, sandwiching the first seal between the flange and the packing base, preventing the lid gasket from being pulled into the pot. In other words, the annular rib of the packing base firmly presses the first seal against the flange of the pot. If the first seal has a convex portion as a pressure recovery path and is firmly sandwiched between the flange and the annular rib of the packing base, compression set may accumulate in the convex portion over time. If compression set accumulates in the convex portion, the convex portion loses its function as a pressure recovery path.

[0159] 14(a), the rice cooker 1 according to this embodiment does not prevent the lid gasket 62 from being pulled into the pot 25 by tightly pinching the upper piece 86 of the lid gasket 62 between the gasket base 63 and the pot 25, but prevents the lid gasket 62 from being pulled into the pot 25 by the engagement between the annular protrusion 91 of the lid gasket 62 and the recess 92 of the gasket base 63. In a situation where the annular protrusion 91 and the recess 92 of the gasket base 63 are engaged, that is, in a situation where the inner lid unit 59 is pulled in by the negative pressure inside the pot 25, the force pressing the protrusion 111 against the flange 32 of the pot 25 is actually reduced, reducing the risk of permanent compression set in the protrusion 111.

[0160] FIG. 15 is a control block diagram of a rice cooker according to an embodiment of the present invention.

[0161] As shown in Figure 15, the rice cooker 1 according to this embodiment operates in coordination with the input / output control circuit board 75 and the heating control circuit board 42. The input / output control circuit board 75 and the heating control circuit board 42 exchange control signals in both directions. The input / output control circuit board 75 outputs a heating control signal to the heating control circuit board 42, and the heating control circuit board 42 outputs a display control signal to the input / output control circuit board 75.

[0162] The rice cooker 1 also includes a coil drive circuit 121 that energizes the heating coil 31, a lid heater drive circuit 123 that energizes the lid heater 58, a lid temperature sensor 125 that detects the temperature of the inner lid 61, a lid opening / closing sensor 126 that is provided inside the lid body 26 and detects the opening and closing of the lid body 26, a pressure sensor 127 that detects the internal pressure of the pot 25, an inner lid attachment sensor 99, and an alarm unit 128.

[0163] The coil drive circuit 121 includes a first drive circuit 121u that applies a high-frequency current to the first coil 31u based on a first heating control signal output from the heating control circuit board 42, and a second drive circuit 121d that applies a high-frequency current to the second coil 31d based on a second heating control signal output from the heating control circuit board 42. The two coil drive circuits 121u and 121d are, for example, at least one of a power supply circuit, an inverter, an IH (Induction Heating) drive circuit, and a switching element. The coil drive circuit 121 increases or decreases the output of the two coils 31u and 31d by changing at least one of the period and the duty cycle of the high-frequency current applied to the two coils 31u and 31d.

[0164] For ease of explanation, it is assumed that the rice cooker 1 is equipped with a switching element that selectively energizes the two coils 31u, 31d. The rice cooker 1 may be capable of energizing the two coils 31u, 31d simultaneously. In other words, there may be a period during which the two coils 31u, 31d are energized simultaneously.

[0165] The lid heater drive circuit 123 supplies DC or AC current to the lid heater 58 based on the lid heating control signal output from the heating control circuit board 42 .

[0166] The lid temperature sensor 125 is a thermistor. The lid temperature sensor 125 detects the temperature of the heat sink 57. The temperature detected by the lid temperature sensor 125, i.e., the temperature of the heat sink 57, correlates with the temperature of the inner lid 61. In other words, the temperature of the inner lid 61 can be inferred from the temperature detected by the lid temperature sensor 125. The temperature of the inner lid 61 inferred from the temperature detected by the lid temperature sensor 125 will hereinafter be referred to as the "lid temperature." The lid temperature detected by the lid temperature sensor 125 is used exclusively to manage the heating temperature of the inner lid 61 by the lid heater 58.

[0167] The lid opening / closing sensor 126 is preferably disposed near the hinge mechanism 27. The lid opening / closing sensor 126 may be a sensor of any detection type, such as an optical type, a mechanical type, or a magnetic type, as long as it can output a detection signal based on the opening or closing of the lid 26 to the input / output control circuit board 75. For example, when the lid 26 is open and tilted relative to the main body 23, the lid opening / closing sensor 126 detects the tilted position of the lid 26. Furthermore, for example, when the lid 26 is closed, the lid opening / closing sensor 126 detects the position of the lid 26.

[0168] Pressure sensor 127 is provided inside lid 26 and detects the pressure on the pot 25 side of pressure regulating valve 67 of steam exhaust passage 66, i.e., the pressure equivalent to the internal pressure of pot 25, and outputs the detected pressure to heating control circuit board 42. Pressure sensor 127 is not necessarily required.

[0169] The inner lid attachment sensor 99 is a mechanical switch that is pushed in when the inner lid unit 59 is attached to the lid body 26 and protrudes when the inner lid unit 59 is removed from the lid body 26. The inner lid attachment sensor 99 detects whether the inner lid unit 59 is attached or not and outputs the result to the heating control circuit board 42.

[0170] The notification unit 128 is at least one of the following: a light source that lights up or flashes, such as a lamp or a light-emitting diode (LED), which appeals to the visual sense of the user of the rice cooker 1; a sound device that emits an electrically synthesized voice or a buzzer sound, which appeals to the auditory sense of the user of the rice cooker 1; or a vibrator, which appeals to the tactile sense of the user of the rice cooker 1.

[0171] The inputs to the input / output control circuit board 75 are operation signals output by the respective key elements of the operation unit 77 and display control signals output by the heating control circuit board 42. Based on these inputs, the input / output control circuit board 75 controls the display operation of the display unit 76, controls the operation of the notification unit 128, and outputs a heating control signal to the heating control circuit board 42.

[0172] The microprocessor of the input / output control circuit board 75 executes a predetermined program to function as an input signal generation unit 132 that generates control signals corresponding to the operation signals output by each key element, a display control unit 133 that controls the display operation of the display unit 76, and a condition setting unit 135 that works in conjunction with the input signal generation unit 132 and the display control unit 133 to enable the presentation, selection, and setting of various conditions that can be selected by the key elements.

[0173] The condition setting unit 135 sequentially presents a plurality of courses including, for example, a cooking course, a rice cooking course, and a maintenance course, and allows the user to select and set a desired course.

[0174] The memory device of the input / output control circuit board 75 stores rice cooking courses corresponding to various conditions that can be selected using key elements, such as rice brand, cooking method, hardness, etc. The display unit 76 displays the various conditions of the courses stored in the memory device, and by accepting operations to select these conditions using the operation unit 77, the course can be selected and set appropriately.

[0175] The heating control circuit board 42 of the main body 23 controls the temperature of the pot 25 and the temperature of the inner lid 61 by adjusting the heating coil 31 and the lid heater 58 during cooking or keeping the rice warm, based on the pot bottom temperature detected by the pot temperature sensor 46 and the lid temperature detected by the lid temperature sensor 125.

[0176] The inputs to the heating control circuit board 42 are the temperature detection signal output by the pot temperature sensor 46, the temperature detection signal output by the lid temperature sensor 125, the internal pressure detection signal output by the pressure sensor 127, the lid open / close detection signal output by the lid open / close sensor 126, and the heating control signal output by the input / output control circuit board 75.

[0177] Based on these inputs, heating control circuit board 42 controls heating coil 31, which heats pot 25 during rice cooking and keeping warm, and lid heater 58, which heats inner lid 61. Heating control circuit board 42 controls the temperature of the bottom of pot 25 mainly by controlling heating coil 31 based on the temperature detection signal output by pot temperature sensor 46. Heating control circuit board 42 controls the temperature of inner lid 61 mainly by controlling lid heater 58 based on the temperature detection signal output by lid temperature sensor 125.

[0178] In addition, the heating control circuit board 42 controls the opening and closing operation of the pressure regulating valve 67 of the steam discharge passage 66, the decompression operation of the decompression pump 68, and the lid locking operation of the lid locking mechanism 72 based on the internal pressure detection signal output by the pressure sensor 127.

[0179] The microprocessor of the heating control circuit board 42 functions as a rice cooking control unit 137 and a keep-warm control unit 138 by executing a predetermined program.

[0180] When a command to start cooking is input to the operation unit 77, the rice cooking control unit 137 performs a rice cooking operation by sequentially executing a soaking process, a boiling heating process, a continuing boiling process, and a steaming process. Also, when a command to start cooking is input to the operation unit 77, the rice cooking control unit 137 sequentially executes the cooking processes.

[0181] The heat retention control unit 138 executes a heat retention process, which includes a simple heat retention process for keeping the rice in the pot 25 at a predetermined heat retention temperature, and a reheating heat retention process for reheating the rice in the pot 25 that is lower than the predetermined heat retention temperature, to the predetermined heat retention temperature.

[0182] The memory device of the heating control circuit board 42 stores pressurization / depressurization types that combine various drive timings for the pressure regulating valve 67 and the pressure reducing pump 68, as well as current supply types for the first coil 31u and the second coil 31d, and combinations of their execution timings for each course.

[0183] The states of rice cooker 1 include, for example, "standby," in which it is waiting without performing any process, "adding soaking," in which it is soaking rice in extra water, "cooking," in which it is cooking rice and water to make cooked rice, "keeping warm," in which it is maintaining the temperature of the rice, and "reserving cooking," in which it is waiting until cooking begins at a predetermined set time. Any of the states that rice cooker 1 is currently executing, "standby," "adding soaking," "cooking rice," "reserving cooking," and "reserving cooking," are included in the current state of rice cooker 1.

[0184] Next, an example of the rice cooking course executed by the rice cooker 1, that is, the rice cooking operation, will be described.

[0185] The food to be cooked is placed in pot 25. Next, pot 25 containing the food to be cooked is placed in pot accommodating section 21 of main body 23, and lid 26 is closed.

[0186] When the power plug of the rice cooker 1 is inserted into a commercial AC power outlet, the rice cooker 1 starts up in an initial state in which it is not performing cooking or keeping rice warm. The initial state is also called a standby state or a stopped state.

[0187] In the initial state, each time a key element of the operation unit 77 is operated, an operation signal corresponding to the operated key element is input to the input signal generation unit 132. The condition setting unit 135 works in cooperation with the input signal generation unit 132 to change the rice cooking course setting, and works in cooperation with the display control unit 133 to display the changed setting on the display unit 76. The display unit 76 visually presents the current rice cooking course setting corresponding to the operated key element to the user of the rice cooker 1.

[0188] When a key element corresponding to the selection of the rice cooking course is operated, an operation signal corresponding to the selection of the rice cooking course is input to the input signal generation unit 132. The condition setting unit 135 stores the rice cooking course displayed on the display unit 76 in a storage device, and outputs a heating pattern corresponding to the selected rice cooking course to the heating control circuit board 42.

[0189] The rice cooking control unit 137 of the rice cooker 1 according to this embodiment performs rice cooking operations including a soaking cooking process, a boiling heating process, a continuous boiling process, and a steaming process according to the heating pattern corresponding to the selected rice cooking course, to cook the food to be cooked until it is cooked rice. The control that executes each process is called by the name of the process. For example, the control that executes the soaking cooking process is called soaking cooking control.

[0190] The soaking process includes a preheating process, a cooking amount determination process for determining the amount of cooked rice, and a soaking process for promoting water absorption by the rice contained in the food to be cooked. Note that the entire soaking process is sometimes called the soaking process in a broad sense, and the soaking process within the soaking process is sometimes called the soaking process in a narrow sense.

[0191] When the soaking process starts, the rice cooking control unit 137 temporarily reduces the internal pressure of the pot 25, restores it to atmospheric pressure, and then operates the pressure reducing pump 68, pressure reducing valve 70, and pressure adjusting valve 67 to restore the reduced pressure again.

[0192] First, the rice cooking control unit 137 operates the solenoid 67b to block the steam exhaust path 66 with the pressure regulating valve 67, opens the pressure reducing valve 70 to allow gas to flow through the path connecting the inside of the pot 25 and the pressure reducing pump 68, and operates the pressure reducing pump 68 to remove the gas from the inside of the pot 25.

[0193] Next, rice cooking control unit 137 operates solenoid 67b to open steam exhaust path 66 using pressure adjustment valve 67, connecting the inside of pot 25 to the outside of rice cooker 1. Outside air then flows into pot 25, which is in a reduced pressure state, from steam outlet 65 via steam exhaust path 66, and the internal pressure of pot 25 returns to atmospheric pressure. After that, rice cooking control unit 137 further operates solenoid 67b to close steam exhaust path 66 using pressure adjustment valve 67, opens pressure reduction valve 70 to allow gas to flow through the path connecting pot 25 and pressure reduction pump 68, and operates pressure reduction pump 68 to remove the gas from inside pot 25.

[0194] In other words, when the soaking process starts, the internal pressure of pot 25 fluctuates. The fluctuations in the internal pressure of pot 25 expel the air inside the rice and allow water to penetrate to the center of the rice in place of the expelled air.

[0195] The display control unit 133 lights up the light-emitting diode directly below the character string "vacuum" each time the internal pressure of the pot 25 is reduced below atmospheric pressure, and turns off the light-emitting diode directly below the character string "vacuum" each time the internal pressure of the pot 25 is restored to atmospheric pressure.

[0196] The start of the soaking process also marks the start of the rice cooking amount determination process. The rice cooking control unit 137 changes the temperature of the pot 25 detected by the lid temperature sensor 125 by heating the pot 25 with the heating coil 31, and determines the amount of rice cooked based on the change in temperature of the pot 25. The temperature of the pot 25 is affected by the temperature of the rice, the temperature of the water, and the temperature of the atmosphere around the rice cooker 1, but usually represents the temperature of the food being cooked.

[0197] When the rice cooking amount determination step is completed, the rice cooking control unit 137 moves to the soaking step. The rice cooking control unit 137 that executes the soaking step energizes the heating coil 31 to heat the pot 25. The energization type applied to the soaking step may be a specific energization type that does not depend on the amount of rice cooked determined in the rice cooking amount determination step, or may be one selected from multiple cooking types with different outputs and energization times of the heating coil 31 depending on the amount of rice cooked, or may be a specific energization type corrected depending on the amount of rice cooked.

[0198] Furthermore, the rice cooking control unit 137 energizes or cuts off the heating coil 31 throughout the entire soaking process so that the temperature of the pot 25 does not exceed 60°C. In this way, the rice cooker 1 prevents the rice from gelatinizing during the soaking process, avoiding poorly cooked rice.

[0199] When the soaking time is over, the rice cooking control unit 137 transitions to the boiling heating process.

[0200] During the boiling heating process, the rice cooking control unit 137 energizes the heating coil 31 until it detects that the food has boiled. The rice cooking control unit 137 heats the food in the pot 25 more strongly than during the soaking cooking process, raising the temperature of the food to boiling temperature in a short period of time. The rice cooking control unit 137 closes the pressure reducing valve 70, stops the pressure reducing pump 68, and opens the pressure adjusting valve 67. This immediately restores the internal pressure of the pot 25 to atmospheric pressure. The display control unit 133 turns off the light-emitting diode located directly below the character string "vacuum."

[0201] The power supply pattern used to boil the food preferably sequentially consists of energizing the first coil 31u, de-energizing a period, energizing the second coil 31d, and de-energizing a period. The rice cooking control unit 137 also preferably changes the power supply time of the heating coil 31 according to the amount of rice to be cooked. For example, the power supply time of the second coil 31d is changed inversely proportional to the amount of rice to be cooked, the power supply time of the first coil 31u is set to be directly proportional to the amount of rice to be cooked, and the power supply interval, i.e., the power supply pattern cycle, is set to be directly proportional to the amount of rice to be cooked.

[0202] Thereafter, when the temperature of the bottom of pot 25 reaches or exceeds a predetermined temperature, for example, 90°C, and the temperature of inner lid 61 reaches or exceeds a predetermined temperature, for example, 90°C, rice cooking control unit 137 opens pressure regulating valve 67 and begins detecting boiling of the food to be cooked under atmospheric pressure. Display control unit 133 lights up the light-emitting diode located directly below the word "Pressurize" based on the internal pressure of pot 25 detected by pressure sensor 127. Rice cooking control unit 137 monitors the rate of temperature rise per unit time of the bottom of pot 25 or the rate of temperature rise per unit time of inner lid 61, and determines that the food to be cooked has boiled when these rates of temperature rise fall below a predetermined rate.

[0203] The energization type used in the process of determining whether the food has boiled is different from the energization type used to boil the food. Also, it is preferable that the rice cooking control unit 137 changes the energization time of the heating coil 31 according to the amount of rice to be cooked, even in the process of determining whether the food has boiled.

[0204] The rice cooking control unit 137 in this embodiment energizes the heating coil 31 with multiple different energization types during the boiling heating process, and energizes the heating coil 31 with even different energization types during the process of determining whether the rice has boiled. In other words, the rice cooker 1 finely adjusts the energization type to suit the boiling of water in the food, reducing uneven cooking of the rice.

[0205] Furthermore, the rice cooking control unit 137 can select, correct, or change the current supply type depending on the amount of rice to be cooked. In this way, the rice cooker 1 can carefully apply the current supply type that is suitable for the amount of rice to be cooked, reducing unevenness in rice cooking.

[0206] When the boiling heating process is completed, the rice cooking control unit 137 transitions to the boiling continuation process.

[0207] During the boiling continuation process, the rice cooking control unit 137 switches the power supply to the heating coil 31 while the pressure regulating valve 67 is closed to maintain the temperature of the bottom of the pot 25 at a predetermined temperature or higher, for example, 98 degrees Celsius or higher, and continuously powers the lid heater 58 to maintain the temperature of the inner lid 61 at a predetermined temperature or higher, for example, 98 degrees Celsius or higher.

[0208] As the food continues to boil, steam generated by the food fills the space inside the pot, increasing the internal pressure of pot 25. When the internal pressure of pot 25 rises above the set pressure, gasket 67ab of pressure adjustment valve 67 is pushed up against the spring force acting from elastic body 67dd, opening pressure adjustment hole 81, and steam inside pot 25 flows out through steam exhaust path 66 and is discharged to the outside of rice cooker 1 through steam vent 65. When the internal pressure of pot 25 falls below the set pressure due to the outflow of steam, gasket 67ab closes pressure adjustment hole 81 due to the spring force acting from elastic body 67dd. In this way, during the boiling continuation step, pressure adjustment valve 67 intermittently opens and closes pressure adjustment hole 81.

[0209] If pressure adjustment hole 81 is blocked by a foreign object, pressure adjustment valve 67 cannot open pressure adjustment hole 81. At this time, steam generated by the food being cooked further fills the space inside the pot, causing the internal pressure of pot 25 to rise further. When the internal pressure of pot 25 reaches a predetermined pressure, gasket 97ab of safety valve 97 is pushed up against the spring force acting from elastic body 97d, opening high-pressure exhaust hole 82 and allowing steam inside pot 25 to flow out into steam exhaust path 66 and be exhausted to the outside of rice cooker 1 through steam vent 65. When the internal pressure of pot 25 falls below the predetermined pressure due to the outflow of steam, gasket 97ab closes high-pressure exhaust hole 82 due to the spring force acting from elastic body 97d.

[0210] If the temperature of pot 25 reaches or exceeds a predetermined temperature, or if the temperature rises at a predetermined rate, for example, 0.5 degrees Celsius or more in 10 seconds, rice cooking control unit 137 determines that the water in pot 25 is starting to run out. When rice cooking control unit 137 determines that the water in pot 25 is starting to run out, it extends the power supply time for heating coil 31.

[0211] When the rate of temperature rise at the bottom of the pot 25 reaches a predetermined rate or exceeds a predetermined temperature, or when the temperature reaches a dry-up temperature at which excess water in the pot 25 disappears, such as 120 degrees Celsius, the rice cooking control unit 137 determines that the food is cooked and ends the boiling continuation process.

[0212] When the boiling continuation process is completed, the rice cooking control unit 137 transitions to the soaking process.

[0213] During the soaking process, the rice cooking control unit 137 switches the power supply to the lid heater 58 based on the lid temperature to prevent condensation from forming on the inner lid 61. The rice cooking control unit 137 also switches the power supply to the heating coil 31 based on the temperature of the pot 25 to manage the temperature of the food being cooked. The soaking process continues for a predetermined period of time.

[0214] When the soaking process is completed, the rice cooking control unit 137 completes the rice cooking operation, and the keep-warm control unit 138 starts the keep-warm process.

[0215] When the rice cooking operation is completed, the heating control circuit board 42 outputs a display control signal corresponding to the completion of the rice cooking operation. The input / output control circuit board 75 receives this display control signal and controls the display operation of the display unit 76 and the notification operation of the notification unit 128 to notify the user that the rice cooking operation is completed.

[0216] Keep-warm control unit 138 causes heating coil 31 to generate heat until the temperature of the rice drops from the freshly cooked temperature, substantially 100°C, to the keep-warm temperature, substantially 73°C, and continues to cause heating coil 31 to generate heat even after the keep-warm temperature has stabilized at 73°C. Keep-warm control unit 138 adjusts the output of heating coil 31 so that the temperature of the bottom of pot 25 remains constant.

[0217] The rice cooker 1 can also reheat the rice in the pot 25.

[0218] Rice cooker 1 according to this embodiment, configured as described above, is equipped with clogging prevention parts 105 that protrude through the holes (high-pressure exhaust hole 82, pressure adjustment hole 81) inside pot 25 when inner lid 61 is closed to prevent the holes from being blocked by the food being cooked. As a result, rice cooker 1 prevents the holes (high-pressure exhaust hole 82, pressure adjustment hole 81) from being blocked by foreign matter, controls the internal pressure of pot 25 to at least a predetermined pressure or less, and reliably prevents the internal pressure of pot 25 from rising abnormally, allowing for smooth rice cooking.

[0219] Furthermore, rice cooker 1 according to this embodiment is equipped with clogging prevention section 105 that protrudes through the holes inside pot 25 with inner lid 61 closed, whether the valve section (safety valve 97, pressure adjustment valve 67) has the holes (high-pressure exhaust hole 82, pressure adjustment hole 81) open or closed. Therefore, even if the food to be cooked as a foreign object is blown up toward the hole by the rapid airflow toward the hole that occurs immediately after the valve section opens, rice cooker 1 reliably prevents the hole from being clogged by the foreign object, and can more reliably perform good rice cooking by controlling the internal pressure of pot 25 to at least a predetermined pressure or less.

[0220] Furthermore, the rice cooker 1 according to this embodiment is equipped with clogging prevention part 105 that has a tapered shape that narrows toward protruding end 105a. Therefore, in the rice cooker 1, clogging prevention part 105 can be smoothly positioned inside pot 25 through the hole without interfering with inner lid unit 59, which is attached to lid body 26 along an arc-shaped path.

[0221] Furthermore, the rice cooker 1 according to this embodiment is provided with a hemispherical protruding end 105a that is positioned inside the pot 25 when the inner lid 61 is closed. This prevents deterioration of the clogging prevention part 105, which is exposed to steam inside the pot 25, due to heat. Furthermore, when the lid 26 is opened, the protruding end 105a of the clogging prevention part 105 that is exposed to the inner lid 61 and that the user can see together with the opening of the pot 25, is rounded, which is preferable in appearance.

[0222] Furthermore, the rice cooker 1 according to this embodiment is equipped with a clogging prevention section 105 provided on the valve body (valve body 97a, valve body 67a) of the valve section (safety valve 97, pressure adjustment valve 67). This reduces the structural complexity of the safety valve 97 in the rice cooker 1, and prevents a decrease in the reliability of the opening and closing operation of the safety valve 97 and in the shutoff performance of the safety valve 97. Furthermore, by integrally molding the clogging prevention section 105 with the valve body that performs the original function of the valve, the rice cooker 1 can reliably prevent an abnormal increase in the internal pressure of the pot 25 without providing any additional parts.

[0223] Furthermore, the rice cooker 1 according to this embodiment may be provided with a safety valve 97 as a valve unit. This prevents foreign matter from clogging the high-pressure exhaust hole 82, and allows the rice cooker 1 to continue cooking rice by controlling the internal pressure of the pot 25 to a predetermined pressure or less.

[0224] Furthermore, the rice cooker 1 according to this embodiment may be provided with a pressure adjustment valve 67 as a valve unit. This prevents foreign matter from clogging the pressure adjustment hole 81, and allows the rice cooker 1 to control the internal pressure of the pot 25 to a set pressure or less, thereby enabling good rice cooking operation.

[0225] Furthermore, rice cooker 1 according to this embodiment is equipped with pressure adjustment valve 67 having multiple fine holes 81a. As a result, rice cooker 1 can simultaneously reduce the flow rate of steam flowing out of pressure adjustment hole 81 and the flow rate of gas flowing in from pressure adjustment hole 81, prevent foreign matter from adhering to pressure adjustment hole 81 and inner lid 61, and prevent gasket 67ab from adhering to the sealing surface of inner lid 61 when the internal pressure of pot 25 is reduced.

[0226] Therefore, with rice cooker 1 according to the present invention, it is possible to reliably prevent the internal pressure of pot 25 from increasing abnormally.

[0227] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0228] 1...rice cooker, 21...pot accommodating section, 23...main body, 25...pot, 25a...main material, 25b...heating element, 26...lid body, 27...hinge mechanism, 31...heating coil, 31u...first coil, 31d...second coil, 32...flange section, 35...bottom plate, 36...upper frame, 37...inner frame, 37a...temperature sensor placement hole, 38...outer frame, 39...controller accommodating chamber, 41...vent, 42...heating control circuit board, 43...radiator, 45...cooling fan, 46...pot temperature sensor, 48...metal plate section, 51...hinge shaft, 52...hinge spring, 55...outer lid, 55a... Recessed portion, 55b...circuit board accommodating recess, 56...outer lid cover, 57...heat sink, 58...lid heater, 59...inner lid unit, 61...inner lid, 62...lid gasket, 63...gasket base, 65...steam port, 66...steam exhaust passage, 67...pressure regulating valve, 67a...valve, 67aa...valve base, 67ab...gasket, 67b...solenoid, 67c...valve drive portion, 67d...valve stem, 67da...follower, 67db, 67dc...cam follower surface, 67dd...elastic body, 67e...valve support portion, 68...pressure reducing pump, 69...pressure reducing hole, 70...pressure reducing valve , 71...lid opening operation button, 72...lid lock mechanism, 73...operation panel, 75...input / output control circuit board, 76...display unit, 77...operation unit, 81...pressure adjustment hole, 81a...narrow hole, 82...high-pressure exhaust hole, 85...base, 86...upper piece portion, 87...lower piece portion, 88...suction cup portion, 89...connection portion, 91...annular protrusion portion, 92...recess, 95...pressure adjustment packing, 97...safety valve, 97a...valve body, 97aa...valve body base, 97ab...packing, 97b...valve body holding cylindrical portion, 97d...elastic body, 98...pressure reduction packing, 99...inner lid attachment sensor, 101...frame, 1 02...pressure regulating valve operating unit, 102a, 102b...cam surface, 103...clamp operation regulating unit, 105...blocking prevention unit, 105a...protruding end, 107...valve unit, 111...convex portion, 112...suction space, 121...coil driving circuit, 121u...first driving circuit, 121d...second driving circuit, 123...lid heater driving circuit, 125...lid temperature sensor, 126...lid opening / closing sensor, 127...pressure sensor, 128...alarm unit, 132...input signal generating unit, 133...display control unit, 135...condition setting unit, 137...rice cooking control unit, 138...keep warm control unit.

Claims

1. A pot capable of accommodating food to be cooked; a main body having a pot accommodating portion capable of accommodating the pot; a lid that can open and close the pot storage section; an inner lid that is detachably attached to the lid body, closes the pot when the lid body is closed on the main body, and has a hole that connects the inside and outside of the closed pot; a valve portion provided on the lid body, the valve portion having a valve body that allows gas to pass between the inside and outside of the pot by opening the hole in the inner lid and blocks gas from passing between the inside and outside of the pot by closing the hole in the inner lid; a clogging prevention portion that protrudes through the hole to the inside of the pot when the inner lid is closed and prevents the food to be cooked from clogging the hole.

2. The rice cooker according to claim 1 , wherein the blocking prevention portion protrudes through the hole to the inside of the pot when the inner lid is closed, whether the valve portion is opening or closing the hole.

3. The rice cooker according to claim 1 or 2, wherein the clogging prevention portion has a tapered shape that narrows toward the protruding end.

4. The rice cooker according to claim 1 or 2, wherein the clogging prevention portion has a hemispherical protruding end disposed on the inside.

5. The rice cooker according to claim 1 or 2, wherein the clogging prevention portion is provided on the valve body.

6. 3. The rice cooker according to claim 1, wherein the valve portion is a safety valve having the valve body that opens the hole when the internal pressure of the pot with the inner lid closed exceeds a predetermined pressure.

7. 3. The rice cooker according to claim 1, wherein the valve unit is a pressure regulating valve having a drive source for driving the valve body to open and close, and capable of regulating the internal pressure of the pot when the inner lid is closed.

8. The inner lid has a plurality of holes including a first hole and a second hole, The valve portion is a safety valve having a valve body that opens the first hole when the internal pressure of the pot with the inner lid closed exceeds a predetermined pressure; 3. The rice cooker of claim 1, further comprising: a second valve body that allows gas to pass between the inside and outside of the pot by opening the second hole in the inner lid and blocks gas from passing between the inside and outside of the pot by closing the second hole in the inner lid; and a pressure regulating valve that has a drive source that opens and closes the second valve body and can adjust the internal pressure of the pot with the inner lid closed to be below the predetermined pressure.

9. The rice cooker according to claim 8 , wherein the second hole has a plurality of pores.

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