rice cooker

Abstract

The present invention provides an electric rice cooker capable of cooking rice with a granular texture and rich flavor. The electric rice cooker (1) of the present invention comprises: an inner pot (5) for accommodating rice (R); an outer pot (4) provided outside the inner pot (5) for accommodating heating water (w); a pot heater (8) for heating the outer pot (4); and a control unit (12) for controlling the heating of the pot heater (8). The control unit (12) controls the pot heater (8) to heat the rice (R) until the heating water (w) reaches a predetermined temperature at which the heating water (w) does not boil. After the rice (R) is heated by the condensation heat of the water vapor on the outer surface of the inner pot (5), the pot heater (8) is heated until the heating water (w) boils. The water vapor generated by the vaporization of the heating water (w) flows into the inner pot (5) to heat the rice (R).

Description

Technical Field

[0001] The invention relates to an electric rice cooker which utilizes water vapor to cook rice. Background Art

[0002] In recent years, various manufacturers have released high-performance rice cookers. Many of these cookers, such as those described in Patent Document 1, cook rice by allowing a starch-based viscous liquid called "rice soup" to flow out from the rice. While the rice soup offers a sweet taste upon consumption, the process of allowing the rice soup to flow out damages the rice, causing the flavor components to be lost. As a result, the cooked rice lacks a grainy texture and rich flavor.

[0003] Furthermore, preventing uneven cooking within the rice cooker presents a challenge. For example, if the rice in the pot is heated solely by the pot's heat, the temperature of the rice on the outside (closer to the pot's walls or bottom) rises, making it more likely to absorb water. Meanwhile, the temperature of the rice on the inside (farther from the pot's walls or bottom) does not rise, making it less likely to absorb water, leading to uneven cooking. To prevent this, a control is implemented that quickly heats the water in the pot and causes convection or agitation of the rice. Regardless of how this control works as a cooking method for producing rice soup, it is not suitable for achieving a grainy texture or rich flavor. For this purpose, heating the rice using not only the heat from the pot but also the heat from the steam, as described in Patent Document 2, is believed to be effective.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-178;

[0007] Patent Document 2: Japanese Patent Publication No. 32-5987. Summary of the Invention

[0008] However, the electric rice cooker described in Patent Document 2 is not controlled by a microcomputer, but rather shuts off the heating of the electric heating device when there is no more heated water in the heating pot. Since the heated water is heated to 100°C at once to heat the rice and water in the rice cooker, it is difficult to cook the rice in a way that does not make it mushy and obtain a grainy texture.

[0009] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an electric rice cooker capable of cooking rice having a grainy texture and rich flavor.

[0010] In order to solve the above-mentioned problems, the electric rice cooker according to the present invention is characterized in that it comprises: an inner pot which contains rice; an outer pot which is arranged outside the inner pot and contains heated water; a heating unit which heats the outer pot; and a control unit which controls the heating of the heating unit, wherein the control unit heats the heating unit until the heated water reaches a specified temperature without boiling, and after heating the rice using the condensation heat of water vapor on the outer surface of the inner pot, heats the heating unit until the heated water boils, so that water vapor converted from the vaporization of the heated water flows into the interior of the inner pot to heat the rice.

[0011] In this rice cooker, the control unit first heats the heating unit until the heated water reaches a predetermined temperature before boiling. This heat, generated by the condensation of water vapor on the outer surface of the inner pot, heats the rice. This allows the rice to absorb water while gradually soaking, minimizing unevenness. For example, if the predetermined temperature is set below 60°C, the rice will absorb water up to approximately 30% without becoming gelatinized, but will not absorb more than this, preventing it from becoming mushy. Next, the control unit heats the heating unit until the heated water boils, allowing the vaporized water to flow into the inner pot and heat the rice. This heats the rice from the sides and below due to the heat from the inner pot, and from above due to the steam flowing into the inner pot. This ensures that the rice is cooked uniformly regardless of its location within the inner pot, preventing it from absorbing excess water and becoming mushy. This results in rice with a consistent texture and rich flavor.

[0012] The rice cooker may include a separation unit for separating the inner pot from the outer pot. This ensures that the outer surface of the inner pot, which is separated from the outer pot, serves as a place for water vapor to condense, thereby stabilizing heating due to the condensation heat of the water vapor.

[0013] Furthermore, the separation unit may include: an abutment portion that abuts against the inner pot when attached to the outer pot to position the inner pot; and a vent portion that forms a path for the water vapor generated by the vaporization of the heated water to pass through. As a result, the inner pot positioned by the abutment portion does not shake inside the outer pot, which can improve the usability of the rice cooker, and the heated water is heated in the space above the outer pot and the inner pot that is sealed to a certain extent by the abutment portion (as in Reference 2, Figure 3 As described above, the upper portion of the heating water between the heating pot and the rice cooker is completely open), which can improve the heating efficiency of the heating water. On the other hand, when the heating water becomes high in temperature and vaporizes, the water vapor can flow into the interior of the inner pot through the gap.

[0014] Furthermore, the inner pot may further include blades projecting outward from the inner pot, and the separation unit may include a plurality of support members that support the blades from below when attached to the outer pot. A space facing each other is formed between the plurality of support members, and water vapor generated by evaporation of the heated water passes through the facing space. This allows the heated water to be heated within the space between the outer pot and the inner pot, which is enclosed to a certain extent by the support members above. This improves the heating efficiency of the heated water. Furthermore, when the heated water reaches a high temperature and vaporizes, the water vapor can flow through the facing space into the inner pot.

[0015] Effects of the Invention

[0016] According to the present invention, it is possible to cook rice with a grainy texture and rich taste while maintaining the shape of the rice. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a perspective view showing the appearance of a rice cooker according to an embodiment for carrying out the invention.

[0018] Figure 2 Yes Figure 1 A three-dimensional diagram of a rice cooker with its lid open.

[0019] Figure 3 yes Figure 1 Partial cross-sectional view of an electric rice cooker.

[0020] Figure 4 Yes Figure 1 Block diagram of the control system of the rice cooker.

[0021] Figure 5 (a) means Figure 1 A perspective view of the exploded state of the outer pot and the spacer of the rice cooker, Figure 5 (b) is a perspective view showing the outer pot and the spacer in the installed state.

[0022] Figure 6 Yes Figure 1 Flowchart of the processing performed by the control unit of the rice cooker.

[0023] Figure 7 Yes Figure 1 Illustration of the temperature change of the outer pot of the rice cooker.

[0024] Figure 8 Yes Figure 1 Illustration of the flow of water vapor in a rice cooker.

[0025] Description of Reference Numerals

[0026] 1 rice cooker

[0027] 4 outer pot

[0028] 5. Inner pot

[0029] 6 Spacer (separation unit)

[0030] 8. Pot heater (heating unit)

[0031] 12 Control Unit

[0032] 24 blades

[0033] 27 Butt

[0034] 28 Recessed part (ventilation part)

[0035] 29 Support

[0036] 30 Facing Space

[0037] w Heating water DETAILED DESCRIPTION

[0038] Embodiments for carrying out the present invention will be described using the drawings.

[0039] Figures 1 to 4 The electric rice cooker according to this embodiment is shown. The electric rice cooker 1 includes a main body 2, a lid 3, an outer pot 4 detachably mounted inside the main body 2 and containing heated water W, an inner pot 5 detachably mounted inside the outer pot 4 and containing rice R and water W, a spacer 6 for positioning the inner pot 5 apart from the outer pot 4, an inner lid 7 detachably mounted inside the lid 3, a pot heater 8 for heating the outer pot 4, a pot temperature sensor 9 for detecting the temperature of the outer pot 4, a heater temperature sensor 10 for detecting the temperature of the pot heater 8, a lid heater 11 for heating the inner lid 7 to prevent water droplets from adhering to the inner lid 7, a control unit (microcomputer) 12 for controlling the heating of the pot heater 8 and the lid heater 11, and a power supply board 13 provided with a pot heater control relay that switches the pot heater 8 on and off under the control of the control unit 12, and a lid heater control triac that switches the lid heater 11 on and off.

[0040] The cover body 3 is provided with: an opening button 14 for opening and closing the cover body 3, a cooking button 15 for starting cooking, a cancel button 16 for canceling cooking, a function button 17 for selecting a cooking mode (a mode related to cooking objects such as "white rice", "brown rice", "porridge", or a mode related to cooking methods such as "mixed rice", "quick cooking", etc.) or making a cooking reservation, and a display unit 18 for displaying various information.

[0041] Outer pot 4 is made of aluminum and includes a bottom wall 19, a peripheral wall 20, and blades 21 projecting from the upper edge of peripheral wall 20 toward the outside of outer pot 4. Inner pot 5, on the other hand, is made of stainless steel and includes a bottom wall 22, a peripheral wall 23, and blades 24 projecting from the upper edge of peripheral wall 23 toward the outside of inner pot 5.

[0042] like Figure 5 As shown, the spacer 6 includes an upper member 25 and a lower member 26 that are annular and made of resin. The upper member 25 and the lower member 26 are attached to the outer pot 4 so as to sandwich the blade portion 21 of the outer pot 4 from above and below.

[0043] The upper member 25 covers the vicinity of the upper edge of the peripheral wall 20 from the inside and partially covers the blades 21 from above. The upper member 25 includes a plurality of abutment portions 27 arranged along the entire circumference of the annular inner surface, which abut against the peripheral wall 23 to position the inner pot 5; a plurality of recesses 28 provided between adjacent abutment portions 27, creating gaps between the abutment portions 27 and the peripheral wall 23; and support portions 29, evenly spaced at three locations on the annular upper surface, which support the blades 24 from below. The lower member 26 covers the blades 21 from the outside and below, preventing direct contact between the user and the heated blades 21. When the abutment portions 27 abut against the peripheral wall 23 and the support portions 29 support the blades 24, and the inner pot 5 is placed inside the outer pot 4, the blades 24 face the blades 21 covered by the spacer 6, forming a facing space 30 between them.

[0044] When the electric rice cooker 1 is cooking, the user puts heated water w into the outer pot 4 until it does not reach the specified water level of the bottom wall 22 of the inner pot 5, puts a specified amount of rice R and water W into the inner pot 5, and operates the function button 17 and the cooking button 14. Figure 6 As shown, the control unit 12 uses the function button 17 to select a mode (step 1 (in Figure 6 In the figure, it is recorded as "S.1". The same applies to the following. )), when the rice cooking button 14 is pressed (step 2), the pot heater 8 is turned on (step 3), and the lid heater 11 is turned on (step 4).

[0045] Then, if Figure 7 As shown, control unit 12 controls pot heater 8 to gradually heat outer pot 4 until, after a predetermined time t1, outer pot 4 reaches a predetermined temperature T1, where the heated water W does not boil (step 5). During this time, water vapor condenses between outer pot 4 and inner pot 5, forming condensation on the outer surfaces of bottom wall 22 and peripheral wall 23. The heat of condensation heats the rice R and water W in inner pot 5. For example, if predetermined temperature T1 is set below 60°C, the rice R will absorb water W to approximately 30% without gelatinization. However, water absorption does not exceed this limit, and the process continues until this point in the soaking process.

[0046] Next, the control unit 12 receives feedback from the heater temperature sensor 10 while maintaining the pot heater 8 at a specified temperature T2 exceeding 100°C (step 6), and keeps the pot heater 8 heating until there is no more heated water w in the outer pot 4 (step 7). When the heated water w evaporates and becomes less than a certain amount of water, the temperature of the outer pot 4 is no longer maintained by the heated water w, and a sharp temperature rise occurs. Therefore, the control unit 12 can determine whether there is no more heated water w based on the detection result of the pot temperature sensor 9. In this boiling process, the water vapor generated by the vaporization of the heated water w heats the rice R and water W from the side and bottom by the bottom wall 22 and the peripheral wall 23, and also as shown in FIG. Figure 8 As shown, the rice R and water W flow through the recess 28, the facing space 30, and between the inner cover 7 and the blade portion 24, and into the inner pot 5, thereby heating the rice R and water W from above.

[0047] When the heated water w is no longer in the outer pot 4, the control unit 12 turns off the pot heater 8 to steam the rice (step 8). This steaming process continues until a predetermined time t2 has elapsed (step 9). When the predetermined time t2 has elapsed, the control unit 12 deems the rice cooking complete and notifies the user of this fact by voice or other means (step 10), and turns off the lid heater 11 (step 11).

[0048] In the electric rice cooker 1 according to this embodiment, the control unit 12 first controls the pot heater 8 to heat the heated water w to a predetermined temperature before boiling. The heat of condensation from the water vapor on the outer surfaces of the bottom wall 22 and the peripheral wall 23 is then used to heat the rice R. This allows the rice R to absorb the water W while gradually soaking the rice R, minimizing unevenness. The control unit 12 then controls the pot heater 8 to heat the heated water w until it boils, allowing the vaporized water w to flow into the inner pot 5, heating the rice R. This heats the rice R from the sides and below due to the heat from the inner pot 5, and from above due to the water vapor flowing into the inner pot 5. This ensures that the rice R is cooked uniformly regardless of its location within the inner pot 5, without absorbing excess water and becoming mushy. This results in rice with a consistent texture and rich flavor.

[0049] In addition, the rice cooker 1 is provided with a spacer 6 for positioning the inner pot 5 in a manner separated from the outer pot 4. Therefore, the outer surface of the inner pot 5 (the outer surface of the bottom wall portion 22 and the peripheral wall portion 23) positioned in a manner separated from the outer pot 4 can be ensured to serve as a place for water vapor to condense, so that the heating due to the condensation heat of the water vapor is stabilized, and the positioned inner pot 5 will not shake inside the outer pot 4, which can improve the usability of the rice cooker 1.

[0050] Furthermore, spacer 6 includes an abutment portion 27 that abuts inner pot 4 and positions inner pot 4 when attached to outer pot 5; a recessed portion 28 that forms a gap (path) for vaporized heated water w to pass through; and three support portions 29 that support blades 24 from below. Spaces 30 are formed between each of the three support portions 29, where blades 21 and 24 face each other. This facing space 30 also allows vaporized heated water w to pass through. Consequently, heated water w is heated within the space above outer pot 4 and inner pot 5, which is somewhat enclosed by abutment portion 27 and support portions 29. This improves the heating efficiency of heated water w. Furthermore, when heated water reaches a high temperature and vaporizes, the vapor can flow into inner pot 5 through recessed portions 28 and facing spaces 30.

[0051] While the embodiments for carrying out the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and appropriate changes may be made without departing from the spirit of the invention.

[0052] For example, the control unit 12 performs control while monitoring the temperature of the outer pot 4 through the pot sensor 8, but may also perform control while monitoring the temperature of the inner pot or the temperature of the heated water.

[0053] In addition, recesses 28 are provided between adjacent abutting portions 27 as ventilation portions. However, an embodiment may also be adopted in which recesses 28 are not provided in the spacer 6, but the spacer 6 abuts against the peripheral wall portion 23 over the entire circumference of the annular shape and ventilation holes for water vapor to pass through are provided at appropriate locations.

Claims

1. An electric rice cooker, characterized in that: have: an inner pot for containing rice; an outer pot, which is arranged outside the inner pot and is used to contain heated water that does not reach the bottom wall of the inner pot; a heating unit that heats the outer pot; and a control unit that controls heating of the heating unit, The control unit controls the heating unit to heat the heating water until it reaches a predetermined temperature before the heating water boils. After heating the rice using the condensation heat of the water vapor on the outer surfaces of the bottom wall and the peripheral wall of the inner pot, the control unit controls the heating unit to heat the heating water until the heating water boils. The water vapor generated by the vaporization of the heating water flows into the inner pot from above through the gap between the inner pot and the outer pot to heat the rice. The rice cooker includes a separation unit for separating the inner pot from the outer pot. The separation unit is annular and includes: an abutment portion that abuts against the inner pot over substantially the entire circumference when mounted on the outer pot to position the inner pot; and a vent portion that forms a path for passage of water vapor generated by vaporization of the heated water. The annular separation unit fixes the relative positions of the outer pot and the inner pot by having its outer surface abut against the outer pot and the abutting portion abut against the inner pot. A recessed portion is provided between adjacent contact portions as the ventilation portion. The recessed portion forms a path for passing water vapor in the vertical direction by recessing the surface of the separation unit contacting the inner pot radially outward.

2. The electric rice cooker according to claim 1, characterized in that The inner pot includes a blade portion protruding toward the outside of the inner pot, The separation unit includes a plurality of support portions that support the blade portion from below when the separation unit is attached to the outer pot. A facing space between the outer pot and the blade portion is formed between the plurality of support portions, and water vapor generated by evaporating the heated water passes through the facing space.

Images