JP2707202B2 - Induction heating rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating type rice cooker that changes the power in accordance with the rice cooking process, changes the convection of heat inside an inner pot, and cooks delicious rice.

[0002]

2. Description of the Related Art Conventionally, this type of induction heating type rice cooker is disclosed, for example, in Japanese Patent Application Laid-Open Nos. 4-319212 and 3-261.
No. 420 is known. These are induction heating of the inner pot containing rice and water by the high frequency magnetic field generated from the induction heating coil connected to the inverter circuit device to cook rice, and according to conditions such as the rice cooking process and the rice cooking capacity,
The control unit determines the power to be supplied and adjusts the power to heat the inner pot with the power. According to the progress of the rice cooking process, the input electric power is appropriately changed according to the rice cooking capacity at that time, and the heating control of the “first chopping medium... This heating control was based on the same concept as the invention often found in a conventional electric rice cooker comprising a resistance heater and a contact portion for opening and closing this energizing circuit.

[0003]

In such a conventional configuration, the power supplied varies according to the rice cooking process, but the variation is on the order of minutes. An induction heating rice cooker cooks rice by induction heating an inner pot containing rice and water with a high-frequency magnetic field generated from the induction heating coil, but in principle, the magnetic field concentrates on the part of the inner pot close to the induction heating coil and becomes strong. Heated.
For this reason, the water temperature of the strongly heated portion quickly rises and convections upward in the inner pot. Since the amount of heat supplied is constant during the above-mentioned several minutes in which the supplied electric power is constant, the manner and intensity of heat convection in the inner pot are stable and constant.

[0004] For this reason, when the electric power is low, the heat is transmitted laterally, the whole lower rice is softly broken, and the upper rice is hardened. Conversely, when the electric power was high, heat was transmitted well upward, and the upper part was cooked plumply and deliciously. However, the lower part of the induction heating coil (heat spot) was softened and collapsed, and the other part was hardened. In addition, while rice in places where high-temperature water flows due to convection contains a large amount of water, rice in other places has low temperature and cannot absorb water sufficiently. Therefore, the cooked rice has a hard portion and a softly collapsed portion, and there is a problem in that, in particular, as the cooked rice capacity is larger, uneven cooking occurs more.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an inner pot containing rice and water by a high-frequency magnetic field generated from an induction heating coil connected to an inverter circuit device. In the induction heating type rice cooker that heats and cooks rice, the electric power adjusting means that changes the output of the inverter circuit device to adjust the electric power for heating the inner pot, and the optimal electric power to be supplied according to the conditions such as the rice cooking process and the rice cooking capacity Input power determining means for determining the heating power of the inner pot by the power adjusting means based on the input power determined by the input power determining means, and increasing / decreasing means for increasing / decreasing the heating power of the inner pot in units of several seconds. Is changed.

[0006]

According to the configuration of the present invention, when the input power determining means determines the optimum power to be input according to conditions such as the rice cooking process and the rice cooking capacity, the increasing / decreasing means sets the power based on the determined input power. The heating power of the inner pot is increased or decreased in several seconds by the adjusting means. As a result, the convection state of the heat inside the inner pot is not always constant but becomes unstable. Because of this, the path through which hot water passes is changed by convection, so that there is no limited portion of the rice that is hard or soft and collapsed, and rice can be cooked with less uneven cooking.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an induction heating rice cooker according to one embodiment of the present invention, FIG. 2 is a configuration diagram of a main part of the induction heating rice cooker, and FIG. It is a characteristic diagram.

In FIG. 1, a protective frame 2 forming an inner wall of the main body 1 is mounted, and an induction heating coil 3 is mounted on a bottom surface of the protective frame 2. An inverter circuit device 4 is mounted inside the main body 1, and the inverter circuit device 4 is electrically connected to the induction heating coil 3.

An inner pot 5 is detachably inserted into and held in the protection frame 2. A temperature sensor 6 for obtaining temperature information is attached to the bottom of the protection frame 2 and is in contact with the bottom of the inner pot 5 to be thermally coupled. A control unit 7 is provided inside the main body 1, and the control unit 7 includes the inverter circuit device 4.
And a temperature sensor 6 for obtaining temperature information.

In FIG. 2, the control unit 7 includes a power adjusting means 8 and an input power determining means 9 for determining an optimum input power to be input in accordance with conditions such as a rice cooking process and a rice cooking capacity. An increasing / decreasing unit 10 is provided for increasing / decreasing the heating power of the inner kettle by the power adjusting unit 8 in a unit of several seconds based on the determined input power. The operation of the inverter circuit device 4 changes according to the output of the power adjusting means 8 instructed by the increasing / decreasing means 10, the intensity of the magnetic field from the induction heating coil 3 acting on the inner pot 5 changes, and the inner pot 5 is heated. The power changes.

The operation of the embodiment having the above-mentioned configuration will be described below.

[0012] The user puts the washed rice and an appropriate amount of water into the inner pot 5 and inserts it into the protective frame 2. Next, when a rice cooker switch (not shown) is operated, the rice cooker operation is started by the operation of the controller 7. A high-frequency magnetic field is generated by the inverter circuit device 4 and the induction heating coil 3, and when this magnetic field passes through the inner pot 5, an eddy current is generated in the inner pot 5 and converted into Joule heat by the electric resistance of the inner pot 5. Fever. Thereby, rice and water are heated and cooked.

For cooking rice, "In the beginning, it's a chorochoro middle dad ..."
As the legend says, the change in the heat regulation accompanying its progress is indispensable, raising the water temperature to about 40 ° C, performing a small amount of heating to maintain it, and making the rice absorb water efficiently at the beginning “Chorochoro” Equivalent "preheating step". Then 10
"Heating process" which is equivalent to "medium papper" that heats to a boil in about a minute. The "cooking process", which is equivalent to "pull the fire around when boiling" to cook without boiling over after boiling. Furthermore, it consists of a series of steps, such as the "double cooking process", which is equivalent to "batch a bunch of straw" that removes excess water with a small amount of heat by sucking water and draining water after the water runs out. ing.

When rice cooking is started by the operation of the user, a "preheating step" starts. In the present embodiment, if the temperature of the temperature sensor 6 is lower than 40 ° C., the input power determining means 9 determines to heat at 200 W, and if the temperature is 40 ° C. or higher, the input power determining means 9 determines 0 W, that is, OFF. When the input power determining means 9 determines to heat at 200 W, the increasing / decreasing means 10 operates to determine the power to be supplied per unit time.

As shown in FIG. 3, the unit time is 5 seconds,
Every 5 seconds, for example, 200W-400W-0W-300W-
The power changes like 100 W, and the power is increased or decreased so that the average value becomes 200 W determined by the input power determining means 9 with one cycle of 30 seconds. The power adjusting means 8 operates in accordance with the power specified by the increasing / decreasing means 10, the operation of the inverter circuit device 4 changes, and the power for heating the inner pot 5 changes.

In the "preheating step", the temperature of the temperature sensor 6 is controlled to be 40.degree.
The rice and water inside are also kept at this temperature. At this time, as the amount of rice increases, the temperature of the temperature sensor 6 becomes lower than 40 ° C., and it takes a longer time to heat. Therefore, the rice cooking capacity is determined based on the required time. The “preheating step” ends when a predetermined time, for example, 15 minutes, elapses, and shifts to the “heating step”.

In the "heating step", the electric power is determined by the input power determining means 9 according to the rice cooking capacity determined in the "preheating step". For example, if it is determined to be 700 W, the increasing / decreasing means 10 performs 700 W-1000 W-0 in the same manner as the “preheating step”.
The power is increased / decreased every 5 seconds as in W-400W...
Are heated by the electric power. The “heating step” is completed in about 10 minutes, and the process proceeds to the “cooking step”.

In the "cooking process", the input power determining means 9 similarly determines the power. For example, if it is determined to be 700 W, the increasing / decreasing unit 10 sets 7 as in the “preheating step”.
The power is increased or decreased every 5 seconds, such as 00W-1000W-0W-400W. Eventually, when the rice absorbs water and the water in the inner pot 5 runs out, the temperature at the bottom of the inner pot 5 rises rapidly, and when the temperature sensor 6 detects this, the process shifts to the “double cooking process”.

In the “double cooking process”, when the temperature of the temperature sensor 6 decreases by a certain amount or more, the input power determining means 9 determines
Although it is determined to heat with W, the power adjusting means 8 is operated at a constant 200 W as it is without going through the increasing / decreasing means 10 only in the “double cooking process”. When the temperature of the temperature sensor 6 exceeds a certain temperature, the heating is stopped. The "double cooking process" is completed after 15 minutes, and the rice is cooked.

The effect of increasing / decreasing power by the increasing / decreasing means 10 in the above-described series of rice cooking process operations will be described below. The high-frequency magnetic field generated from the induction heating coil 3 passes through the protection frame 2 and acts on the inner pot 5 made of a magnetic material placed thereon. However, since the magnetic field right above the induction heating coil 3 is the strongest, the inner pot 5 has the highest temperature just above the induction heating coil 3 (hereinafter referred to as a heat spot), and the rice and water around it are heated the most. Although a large amount of water and rice are present in the inner pot 5, the heated water rises and convection occurs.

Since the positional relationship between the induction heating coil 3 and the inner pot 5 does not change, the heat spot is substantially constant regardless of the heating power. However, the manner of convection and the strength of convection change depending on the electric power. For example, when the electric power is low, the water in the heat spot portion is heated and tends to convect upward. However, since the rice is present, the resistance is large, and the heat convects only in the lower portion of the inner pot 5 and spreads laterally. Conversely, when high power is applied, the heat spot is strongly heated, breaking through the resistance of rice and convection violently upward. As a result, heat is transmitted upward, but heat is less likely to be transmitted to portions other than the heat spot at the bottom of the inner pot 5.

In the conventional induction-heated rice cooker, the electric power is uniformly heated with the electric power determined as described above, so that convection changes are small and cooking unevenness is likely to occur, but in the structure of the present invention, as described above, Since the power is finely changed every 5 seconds by the increasing / decreasing means 10, the convection manner and strength are not stable but always change. For this reason, heat is evenly transmitted upward and downward, and the inside of the inner pot 5 always rises at a substantially uniform temperature, so that cooking unevenness is reduced and the whole can be finished in a pleasing and delicious manner.

In the above embodiment, the "double cooking process" is used.
Although the power was not increased or decreased by the increasing / decreasing means 10, the effect of the change in convection was not effective when the water completely disappeared, and the electric power could be increased / decreased by the increasing / decreasing means 10. .

Although the unit time at which the power is changed by the increasing / decreasing means 10 is set to 5 seconds, the purpose of the present invention is to increase or decrease the power during a relatively short time, and the present invention is not limited to this. The power and time may be changed, such as 300 W-3 seconds, 600 W-10 seconds, etc.

Further, in the present embodiment, the average value of the increase / decrease is set to coincide with the power determined by the input power determining means 9 with 30 seconds as one cycle, but it may be 10 seconds or 3 minutes. In short, the condition is such that the convection instability, which is the effect of the present invention, can be obtained, and the shapes of the induction heating coil 3 and the inner pot 5,
It is determined by the positional relationship.

Further, in the present embodiment, the input power determining means 9 determines “preheating”, “heating”, “cooking”, and “double cooking” of the cooked rice.
Although the optimum input power is output for each step, the optimum input power may be determined as appropriate so that the power changes more finely in each step. That is, 10
The 15-minute process may be further subdivided, for example, the input power may change every two minutes.

Here, if the operation of the input power determining means 9 is made very fine, such as every 5 seconds, and the input power is changed at any time, an effect of destabilizing the convection is produced as in the present embodiment. In this case, if the average value of the input power for each rice cooking process is changed as in the beginning, the operation and the effect are exactly the same as those of the present embodiment in which the increasing / decreasing means 10 is provided. The power determining means 9 includes the function of the increasing / decreasing means 10 and is included in the configuration of the present invention.

[0028]

As described above, according to the present invention, an increase / decrease means for increasing / decreasing the heating power of the inner pot by the power adjustment means is provided on the basis of the input power determined by the applied power determination means. Because the power is increased or decreased, the convection method inside the inner pot changes constantly, and the convection changes the path through which hot water passes, so that the hard part of the rice or the part that collapsed softly can be limited There is an effect that it is possible to provide an induction heating type rice cooker that cooks delicious rice with little unevenness in cooking regardless of the amount of cooked rice.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an induction heating rice cooker according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of the induction heating type rice cooker.

FIG. 3 is a diagram showing a power change and a temperature characteristic of the induction heating rice cooker.

[Explanation of symbols]

 Reference Signs List 3 Induction heating coil 4 Inverter circuit device 5 Inner pot 8 Power adjustment means 9 Input power determination means 10 Increase / decrease means

Claims (1)

(57) [Claims] An induction heating rice cooker for induction heating a rice cooker (5) containing rice and water and cooking rice by a high frequency magnetic field generated from an induction heating coil (3) connected to an inverter circuit device (4). A power adjusting means (8) for adjusting the power for heating the inner pot (5) by changing the output of the inverter circuit device (4), and an optimal power to be supplied according to conditions such as a rice cooking process and a rice cooking capacity; Power determining means (9) for determining the heating power, and the heating power of the inner pot (5) is increased or decreased in seconds by the power adjusting means (8) based on the supplied power determined by the supplied power determining means (9). Increase / decrease means (1
0), wherein the convection of heat inside the inner pot (5) is changed during rice cooking.