JP2003259973A - Rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rice cooker capable of uniformly cooking delicious rice. <P>SOLUTION: In the rice cooker having a rice cooker body 1, an inner container 4 in the body 1, an inner pot 2 removably stored in the inner container 4, a heating device 11 arranged outwardly of the inner container 4, a lid 3 covering an opening in the top face of the inner pot 2 and openably formed, the heating device 11 is formed of a plurality of induction heating coils, and a control means individually controlling the induction heating coils 7, 8, 9 and 10 is provided. In the preheating process of rice cooking, induction heating coils 7 and 8 of the side are energized with maximum power, in the finishing process, induction heating coils 9 and 10 of the bottom are energized with maximum power, and in the boiling maintenance process, the side and bottom induction heating coils are alternately energized, and a heating process is provided in a control section 15. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a rice cooker for general households, and to a heating control method for an induction heating coil. 2. Description of the Related Art A conventional rice cooker of this type and a method of controlling an induction heating coil will be described with reference to FIG. [0003] A conventional rice cooker is composed of a main body 1 of the rice cooker.
An inner pot 2 housed in an inner container 4 in the main body 2, an openable / closable lid 3 covering an upper opening of the inner pot 2, and an inner container 4
An induction heating coil, which is a heating device 11 disposed at a fixed space distance from the inner pot 2 at the bottom of the induction heating coil 1;
It comprises a ferrite 5 provided so as not to leak magnetic flux below 1 and a temperature sensor 6 for detecting the temperature of the inner pot 2. Reference numeral 14 denotes an inverter board;
Is a control unit composed of a control board. The outer shell of the inner pot 2 is made of a magnetic material having a high skin resistance. When rice cooking is started, a high-frequency magnetic field is generated by the inverter board 14 and the induction heating coil 11, and the outer shell of the inner pot 2 is exposed to the high-frequency magnetic field. An induced electromotive force is generated on the surface, an eddy current flows, and the inner pot 2 generates heat due to the skin resistance of the inner pot 2. [0005] The induction heating coil 11 is connected to the inverter board 1.
4 and is repeatedly energized and stopped by a control signal of the control unit 15 to heat the inner pot 2. The lid 3 closes the inner pot 2 to prevent spills during cooking and to release steam to the outside, thereby preventing the rice from leaking out of the main body 1 of the rice cooker. The temperature sensor 6 is located at the center of the bottom of the inner container 4 and is in contact with the bottom surface of the inner pot 2 when the inner pot 2 is stored in the main body 1 to detect the temperature of the bottom of the inner pot 2 and control the controller 15. To convey temperature information to the In the rice cooker having such a configuration, the main body 1
The rice cooker 2 containing a predetermined amount of washed rice and a maximum amount of cooked rice and water is stored therein, and the lid 3 is closed to start cooking rice. When the rice cooking is started, a program incorporated in the control unit (control board) 15 causes “preheating”, “cooking”, “keep boiling”,
Each step of “Murashi” is executed according to the temperature information of the temperature sensor 6 in contact with the bottom surface of the inner pot 2 to heat the inner pot 2. [0008] In the rice cooker of the prior art, the problem is that the inner pot 2 is heated by the induction heating coil 11 below the inner container 4. Since the rice is heated only by the lower induction heating coil 11, the rice in contact with the bottom of the inner pot 2 immediately above the induction heating coil 11 is deformed into a dumpling shape due to excessive heat supply. This rice is hard rice because heat is hardly transmitted to the surface, and there is a problem that the rice is easily made uneven in the inner pot 2. [0009] In particular, the unevenness of the rice is such that this tendency becomes more pronounced as the inner pot 2 is thinner. [0010] In addition, in the case of rice cooking, there are various combinations from the case of cooking a small amount of rice to the case of cooking the maximum amount of cooked white rice, and a variety of combinations of rice cooking menus (cooking, cooking, etc.). Although adjustment (electric power) is necessary, in order to estimate how many cups of rice are actually contained in the inner pot 2, the inner pot 2 is heated by "cooking", and the input power and temperature rise. Since the amount of cooked rice is determined from information such as values, there is a problem that unevenness in cooking occurs at the time of the determination. In order to solve the above-mentioned problems, the present invention provides a heating device comprising a plurality of induction heating coils at an upper portion (side portion) and a lower portion (bottom portion) of an inner pot, It has control means to control each induction heating coil individually.Electric heating coil on the side part is energized with maximum power in the preheating process of rice, and induction heating coil on the bottom part is energized with maximum power in the cooking process In the step of maintaining boiling, the induction heating coils on the side and bottom portions are alternately energized and heated, or in the step of maintaining boiling, a heating step of alternately heating the induction heating coils on the bottom portion is provided. According to the present invention, by adopting such a configuration and control, it is possible to obtain delicious rice without uneven cooking. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a rice cooker showing one embodiment of the present invention. FIG. 2 is a heating operation pattern diagram at the time of maximum rice cooking, and FIG. 3 is a heating operation pattern diagram at the same time of minimum rice cooking. FIG. 4 is a control circuit block diagram. In the figure, 1 is a main body of a rice cooker, 2 is an inner pot removably housed in the main body 1, and 3 is a lid for closing and sealing the inner pot 2. Reference numeral 4 denotes an inner container, which is formed by a middle container 4a and a bottom container 4b. The middle container 4a is sandwiched between the bottom container 4b and the main body 1, and the bottom container 4b supports the middle container 4a. Reference numeral 6 denotes a temperature sensor attached to the center of the bottom container 4b. Reference numeral 7 denotes a first induction heating coil attached to the upper outer surface of the middle container 4a, 8 denotes a second induction heating coil attached immediately below the first induction heating coil 7, and 9 denotes a third induction heating coil attached to the bottom container 4b. The induction heating coil 10 is a fourth induction heating coil mounted below the bottom container 4b. The first induction heating coil 7 and the second induction heating coil 8 on these side surfaces and the third induction heating coil 9 and the fourth induction heating coil 10 on the bottom surface constitute a heating device 11. Reference numeral 5 denotes a ferrite mounted on the lower surface of the third induction heating coil 9 and the fourth induction heating coil 10. Reference numeral 12 denotes a shield ring provided on the side surface. When the upper induction heating coils 7 and 8 operate, electromagnetic waves are transmitted to the outside. To prevent leakage. Reference numeral 13 denotes a bottom shield plate for preventing leakage of electromagnetic waves in the lower direction when the fourth induction heating coil 10 operates. Reference numeral 14 denotes each of the induction heating coils 7, 8, 9, 10
And control means 14a including control elements 1 to 4 for controlling the energization and stop of the induction heating coils 7, 8,
This is an inverter board provided so as to be paired with 9, 10. Reference numeral 15 denotes a control unit, which is connected to the inverter board 14 and receives each of the induction heating coils 7, 8, 9, and 10 and the temperature information of the temperature sensor 6 via the inverter board 14. It comprises a control board for controlling the operation and stop of the coils 7, 8, 9, 10. FIG. 4 is a block diagram showing a control circuit according to the present invention, in which a first induction heating coil 7 and a second induction heating coil 8 are provided.
And the third induction heating coil 9 and the fourth induction heating coil 10
Means control elements 1, 2, which are control means 14 a of the inverter board 14 paired with the induction heating coils 7, 8, 9, 10 in response to a control signal of a control section (control board) 15.
3, 4 are driven and each induction heating coil 7, 8,
9 and 10 are energized and stopped, and the inner pot 2 is heated and controlled. An operation example of the above configuration will be described in detail with reference to FIG. 1 and circuit block diagrams of FIGS. 2, 3 and 4 showing an example of a heating pattern. FIGS. 2 and 3 show the temperature sensor 6 in the rice cooking process.
FIG. 3 shows the temperature output of each of the induction heating coils 7, 8, 9, and 10, and shows the energization pattern when the maximum amount of rice is cooked (FIG. 2) and the minimum amount of rice cooked as typical examples. This will be described with reference to the energization pattern in the case (FIG. 3). (1) When rice is cooked at the maximum amount of cooked rice (see the heating operation pattern in FIG. 2) Predetermined rice and predetermined water are put into the inner pot 2, the lid 3 is closed, and rice cooking is started. In the preheating immediately after the start of rice cooking, the first induction heating coil 7 and the second induction heating coil 8 on the side are operated at the maximum power, and the temperature of the rice inside the inner pot 2 is preceded by the temperature of the side and the surface. To rise. The time until the temperature inside the inner pot 2 reaches T1 is measured by the control board 15 based on the information of the temperature sensor 6, and the time Ta is calculated from the rice cooking amount and the determination time (T) in FIG.
Is more than Y seconds and less than X seconds, the amount of cooked rice is estimated to be the maximum, and the input power for heating during cooking is determined. After the preheating process is completed, the process proceeds to the cooking process, in which the third induction heating coil 9 and the fourth induction heating coil 10 on the bottom are operated at the maximum power, and the temperatures near the bottom of the pot and the center of the pot are reduced. The time Tb rising to T2 is measured. The time Tb required to raise the amount of cooked rice in the inner pot 2 from T1 to T2 and the time Tc required to fall from the temperature T2 to T1 'are measured again, and the amount of cooked rice and the determination time (T) in FIG. Is determined to be the maximum amount of cooked rice again when it is determined to be Y seconds or more and less than X seconds, and the energizing time and operating power to each induction heating coil 7, 8, 9, 10 in the subsequent cooking step and boiling maintaining step. To determine. In the step of maintaining the maximum amount of cooked rice, the outputs of all the induction heating coils are made the same, and the side portions (the first induction heating coil 7 and the second induction heating coil 8) and the bottom portion (the third induction heating coil 9) are set. And the fourth induction heating coil 10) are alternately energized to heat the inner pot 2. Therefore, the temperature of the bottom of the inner pot 2 does not rise sharply, and the rice inside the inner pot 2 is not locally heated. The time of the temperature T3 can be secured. When the temperature of the bottom of the inner pot 2 exceeds the cooking temperature T4, the rice cooking process is terminated and the process proceeds to the rice drying process. In the rice drying process, the induction heating coil (third induction heating coil 9) on the bottom portion is used. And the fourth induction heating coil 10) are alternately and minutely energized to blow off excess water of the rice. When the rice bun is completed and the lid 3 is opened and the rice in the inner pot 2 is stirred, the rice is heated uniformly, so that the rice is cooked on the upper part of the inner pot 2 and the bottom part of the inner pot 2. There is no unevenness and it is cooked uniformly. (2) When rice is cooked with the minimum amount of cooked rice (see the heating operation pattern in FIG. 3) Predetermined rice and predetermined water are put into the inner pot 2, the lid 3 is closed, and rice cooking is started. When rice cooking is started, the first induction heating coil 7 and the second induction heating coil 8 on the side are operated at the maximum power in the initial stage of preheating to heat the inner pot 2. The time required for the internal temperature to reach T1 is measured by the control board 15 based on the information of the temperature sensor 6, and when the measured time Ta is less than Z seconds from the rice cooking amount and the determination time in FIG. Presumes that the amount of cooked rice is the minimum, and the control after the preheating is performed by using the first induction heating coil 7 and the second induction heating coil 8 with the rice inside the inner pot 2 so that the temperature of the inner pot 2 is not excessively increased. After heating until the water is almost saturated at T1, the process shifts to a stop, and the rice and water temperature in the inner pot 2 are made uniform. After the preheating process is completed, the process proceeds to the cooking process, in which the third induction heating coil 9 and the fourth induction heating coil 10 are operated at the maximum power and the time Tb until the temperature inside the inner pot 2 rises to T2. Time. The temperature information sent from the temperature sensor 6 is T
When it exceeds 2, the control elements 3 and 4 of the inverter board 14 are stopped, heating is stopped, and the operation is stopped. And the temperature sensor 6
A time Tc during which the temperature of T2 falls from T2 to T1 'is measured. The time Tb required for raising the amount of cooked rice in the inner pot 2 from T1 to T2 is the amount of cooked rice and the determination time Z in FIG.
When the time is less than a second, it is determined that the amount of cooked rice is the minimum, and each of the induction heating coils 7, 8, and
The power supply time to 9 and 10 and the operating power are determined. In the case of the minimum value, in the cooking process, the third induction heating coil 9 and the fourth induction heating coil 10 are energized for a short time with maximum electric power, and the inner pot 2 is heated. Accordingly, heating is performed without the water of the cooked rice inside the inner pot 2 evaporating rapidly. It continues even after the boiling is detected by the temperature sensor 6 and alternately heats only with the induction heating coils 9 and 10 on the bottom part in the power supply cycle of the minimum power, thereby turning the rice in the inner pot 2 into α to maintain the temperature T3 for maintaining the boiling. Time can be secured. When the temperature of the bottom surface of the inner pot 2 exceeds the temperature T4, the rice cooking process is terminated, and the process shifts to the spotting process. The fourth induction heating coil 10 on the bottom is
Turn on only a small amount of electricity to remove excess water from the rice. When the rice porridge is completed and the lid 3 is opened and the rice in the inner pot 2 is stirred, the rice in the inner pot 2 is cooked uniformly without being boiled because it is not excessively heated. As described above, according to the present invention having such a configuration, a plurality of induction heating coils are provided, and a means for individually controlling each induction heating coil is provided. In the induction heating coil on the side part is supplied with the maximum power, the induction heating coil on the bottom part is supplied with the maximum power in the cooking process, and the induction heating coil on the side part and the bottom part is supplied alternately in the boiling maintenance step. And a heating step for heating
It is possible to provide deliciously cooked rice without uneven cooking.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing one embodiment of a rice cooker according to the present invention. FIG. 2 is a heating operation pattern diagram at the time of maximum rice cooking according to the embodiment. FIG. 3 is a diagram showing a heating operation pattern at the time of minimum rice cooking according to the embodiment. FIG. 4 is a control circuit block diagram of one embodiment. FIG. 5 is a diagram showing the relationship between the amount of cooked rice and the determination time in one embodiment of the rice cooker of the present invention and a conventional example. FIG. 6 is a sectional view showing a conventional rice cooker. [Explanation of reference numerals] 1: body, 2: inner pot, 3: lid, 4: inner container, 7: first
Induction heating device, 8: second induction heating device, 9: third induction heating device, 10: fourth induction heating device, 11: heating device, 1
4: Inverter board, 14a: control means, 15: control unit (control board).

Claims (1)

Claims: 1. A rice cooker main body (1), an inner container (4) in the main body (1), and an inner pot (2) removably stored in the inner container (4). And a heating device (11) disposed outside the inner container (4) and a lid (3) that covers the upper opening of the inner pot (2) and is configured to be openable and closable. , The heating device (11) is constituted by an induction heating coil, and a plurality of the induction heating coils are provided on a side surface and a bottom surface of the inner pot (2).
(8) The control means (14a) for individually controlling (9) and (10) is provided. In the preheating step of cooking rice, the induction heating coils (7) and (8) on the side portions are energized with maximum power, In the cooking process, the induction heating coils (9) and (10) on the bottom portion are energized with maximum power, and in the process for maintaining boiling, the induction heating coils (7) and (8) on the side portion and the induction heating coil on the bottom portion (9) and (10) are alternately energized and heated, or in the step of maintaining boiling, a heating step of alternately energizing and heating the induction heating coil (9) and the induction heating coil (10) on the bottom portion is provided. A rice cooker characterized by that: