JP3109704B2 - 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 in which the amount of heating is changed in accordance with a rice cooking process so that convection of water inside an inner pot is sufficiently performed to cook delicious rice.

[0002]

2. Description of the Related Art An induction heating type rice cooker of this type is conventionally known, for example, from JP-A-4-31912.
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, and cook the rice. In, the heating amount to be charged was determined, and the heating amount was adjusted so as to heat the inner pot with the heating amount. In accordance with the progress of the rice cooking process, the amount of heat to be supplied changes as appropriate in accordance with the rice cooking capacity at that time, and the heating control of "Initially chopping in the middle ..." was performed. 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 induction heating type rice cooker, an inner pot containing rice and water is induction heated by a high frequency magnetic field generated from an induction heating coil to cook rice. The magnetic field concentrates on a portion near the induction heating coil and is heated strongly (hereinafter referred to as a heat spot). In a rice cooker, it is indispensable to control the amount of heating by changing the amount of heating according to the rice cooking process, the rice cooking capacity and the like. For this reason, when the heating amount is large, the water temperature of the strongly heated portion on the heat spot rises quickly, and the temperature difference with the upper part of the inner pot becomes large, so that the resistance of the rice on the heat spot can be violated violently Convection upwards. However, when the amount of heating is small, the water temperature on the heat spot rises slowly and breaks down the resistance of the rice and cannot convect upward, so that the convection spreads horizontally across the bottom of the inner pot. For this reason, the rice at the bottom, which becomes the path of high-temperature water due to convection, becomes rice-like rice with a large amount of water, and the rice above the temperature, which does not rise, becomes hard rice because it cannot absorb enough water. Become. Therefore, there is a problem that the cooked rice has a hard portion and a softly disintegrated portion, resulting in large uneven cooking. In addition, there is a problem that the heating amount cannot be sufficiently reduced.

In addition, if the power of the inverter circuit device is controlled to be too low, there is a large loss, and the inverter circuit device may generate heat and be destroyed.

[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 for heating and cooking rice, heating amount adjusting means for adjusting the amount of heating for changing the output of the inverter circuit device and heating the inner pot,
A heating amount determining means for determining an optimal heating amount to be supplied according to conditions such as a rice cooking process and a cooking capacity, and a heating amount when the heating amount determined by the heating amount determining means is higher than a predetermined heating amount. Heating is continuously performed by the heating amount determined by the heating amount determining unit by the adjusting unit, and when the heating amount determined by the heating amount determining unit is lower than the predetermined heating amount, it is determined that intermittent heating is repeated by repeating ON-OFF. When the intermittent energization is selected by the determining means, the heating amount at the time of ON by the heating amount adjusting means is ON time / (ON time + OF) with respect to the heating amount determined by the heating amount determining means.
F) The reciprocal of the ratio, and the convection of water inside the inner pot was sufficiently performed even when the heating amount was reduced.

[0006]

According to the configuration of the present invention, the heating amount determining means determines the heating amount to be supplied (for example, 600 W) in accordance with the conditions such as the rice process and the cooking capacity, and the determined heating amount is determined by the determining means. If the heating amount is higher than a predetermined heating amount (for example, a low heating amount 500 W that does not hinder the heat generation of the inverter circuit device), the continuous energization is selected by the determining unit, and the output of the inverter circuit device is adjusted by the heating amount adjusting unit. The inner pot is continuously heated at the determined heating amount (600 W). With this heating amount, the inside of the inner pot sufficiently convects from the bottom to the top.

Next, the heating amount (for example, 300 W) determined by the heating amount determining means is changed to a predetermined heating amount (500 W).
If it is lower, the determining means selects the intermittent energization that repeats ON-OFF (for example, a cycle of 5 seconds ON-10 seconds OFF) and the heating amount (30 seconds) determined by the heating amount determining means.
0 W) through the heating amount adjusting means at a heating amount (therefore, 300 W × 3 = 900 W) which is a reciprocal multiple of an ON time / (ON time + OFF time) ratio (for example, 5 / (5 + 10) = 1/3). Repeat the inner pot repeatedly (5 seconds ON-10 seconds OF
(Cycle F). The average heating amount during this one cycle is the heating amount (300
W).

In the induction heating, since the inner pot generates heat directly, the reaction to the heating is fast.
Since the convection is caused by violent heating during intermittent heating at the heating amount (for example, 900 W for 5 seconds ON), convection cannot be performed upward as in the related art, and there is no uneven heating.

As a result, the convection state of heat inside the inner pot is not always constant and becomes unstable, so that the path through which hot water passes is changed by the convection, so that only a part of the rice is hardened or softly collapsed. It can cook rice with less unevenness and no cooked parts.

[0010]

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 sectional view of an induction heating rice cooker according to an embodiment of the present invention, FIG. 2 is a control block diagram of the induction heating rice cooker, and FIG. 3 is a rice cooker of the induction heating rice cooker. FIG. 4 is a flow chart showing the operation of the main part of the induction heating type rice cooker, and FIG. 5 is a heating state diagram of the conventional induction heating type rice cooker as rice cooking progresses.

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

An inner hook 5 is detachably inserted into and held in the protection frame 2. A temperature sensor 6 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. The control unit 7 is connected to the inverter circuit device 4 and a temperature sensor 6, and obtains temperature information from the temperature sensor 6.

In FIG. 2, the control unit 7 includes a heating amount adjusting means 8, a heating amount determining means 9 for determining an optimum heating amount to be supplied in accordance with conditions such as a rice cooking process and a cooking capacity, and a heating amount determining means. A judging means 10 for selecting the heating amount of the inner pot by the heating amount adjusting means 8 based on the heating amount determined in 9 is provided. The operation of the inverter circuit device 4 changes according to the output of the heating amount adjusting means 8, and changes the strength of the magnetic field acting on the inner pot 5, thereby adjusting the heating amount of the inner pot 5.

The operation of this embodiment having the above configuration will be described below (see FIGS. 3 and 4).

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 chorochoro middle papa ..."
As the legend says, it is essential that the change in the heat control accompanying its progress is indispensable. Raise the water temperature to about 40 ° C, perform a small amount of heating to maintain it, and make the rice absorb water efficiently. Equivalent "preheating process". 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", which 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 user's operation, a "preheating step" starts. If the temperature of the temperature sensor 6 is lower than 40 ° C., the heating amount determining means 9 determines to heat at 300 W, and if the temperature is 40 ° C. or more, the heating amount determining means 9 determines 0 W, that is, OFF. When the heating amount determining means 9 determines to heat at 300 W, the determining means 10 operates next. The determination means 10 uses 500 W as a criterion, and when the heating amount determination means 9 determines 300 W, intermittent energization is selected. The intermittent energization is a cycle of 10 seconds ON-10 seconds OFF.
/ 2, which is 2 which is the inverse multiple of the determined 300W.
Heating is performed in a cycle where 600 W twice is turned on for 10 seconds and turned off for 10 seconds.

The average heating amount during one cycle is 300 W as determined by the heating amount determining means 9. Here, if the output of the inverter circuit device 4 is adjusted by the heating amount adjusting means 8 and the heating is continuously performed at 300 W, the heat spot at the bottom of the inner pot 5 is slowly heated, so that heat is blocked by the rice. As a result, convection hardly occurs at the top, and only the water temperature at the bottom rises, and the water temperature at the top does not rise much. For this reason, in the "preheating process" for water supply of rice, there arises a problem that the upper rice cannot be sufficiently supplied with water. As mentioned above,
600W and OFF intermittent heating, 600W
During heating, it is heated violently, breaking the resistance of rice and causing upward heat convection.

In the "preheating step", as described above, the temperature of the temperature sensor 6 is controlled so as to be 40 ° C. However, as the amount of rice increases, the temperature of the temperature sensor 6 becomes lower than 40 ° C. Requires a large amount of heating. This "preheating process"
The control unit 7 determines the rice cooking capacity based on the heating amount required during 15 minutes, and shifts to the next “heating step”.

In the "heating step", the heating amount is determined by the heating amount determining means 9 in accordance with the rice cooking capacity determined in the "preheating step". For example, if it is determined to be 700 W, continuous power supply is selected by the judging means 10, and continuous heating at 700 W constant is performed by the heating amount adjusting means 8. 7 selected
In the case of 00W, the heating amount is sufficiently large, so that the water in the inner pot 5 convects upward from the bottom and is uniformly heated.
When the temperature of the temperature sensor 6 reaches about 100 ° C., the “heating step” ends, and the process shifts to the “cooking step”.

Also in the "cooking step", the heating amount is determined by the heating amount determining means 9, for example, 450 W. Since the intermittent energization is selected by the judging means 10 at this heating amount, energization is performed at a cycle of 900 W, which is the reciprocal of the energization ratio, for 10 seconds and OFF for 10 seconds, as in the “preheating step”. In the “cooking process”, the inside of the inner pot 5 is in a boiling state, and the rice has already become sticky and the resistance to convection has increased. If the bottom is heated intensely by heating at 900 W for 10 seconds, this resistance will be broken and several paths for hot water will be created. This path is a popular crab hole, through which hot water blows up from the bottom and violently flows,
Finished with even and delicious rice. If determined 450
If it is continuously heated with W, crab holes will not be formed due to the resistance of sticky rice, and the rice below will absorb more water than necessary before heat is not sufficiently transmitted upward and water will be lost Therefore, the lower part will be sloppy rice and the upper part will be hard rice.

When the rice absorbs water and the water inside the inner pot 5 runs out, the temperature at the bottom of the inner pot 5 rises rapidly. When the temperature sensor 6 detects this, the process shifts to the “double cooking process”.
In the “double cooking process”, constant heating is performed by a predetermined heating program, and the process is completed after 15 minutes have elapsed, so that the rice is cooked.

In the above embodiment of the present invention, the intermittent heating is one cycle of ON for 10 seconds and OFF for 10 seconds, and the energizing ratio is set to 1/2. However, a lower heating amount such as 150 W is determined. In case, intermittent heating is 5 seconds ON-15 seconds OF
The determination unit 10 may have a function of switching to one cycle of F and reducing the energization ratio to 1/4. In this case, the reciprocal multiple of the determined 150 W energization ratio, that is, 150 W × 4
= 600 W is the amount of heating during ON for 5 seconds. Thus, the effect of the present invention can be obtained even with a heating amount lower than the lower limit heating amount that does not hinder the heat generation of the inverter circuit device 4.

[0024]

As described above, according to the present invention, when the heating amount determined by the heating amount determining means is higher than a predetermined heating amount, the heating amount determined by the heating amount determining means by the heating amount adjusting means is used. When the heating is performed continuously, and the heating amount determined by the heating amount determining means is lower than the predetermined heating amount, a determining means of intermittent heating that repeats ON-OFF is provided. The heating amount at the time of ON by the heating amount adjusting means when the energization is selected,
ON for the heating amount determined by the heating amount determining means
As the reciprocal multiple of the time / (ON time + OFF time) ratio,
Since the average heating amount during the ON-OFF cycle is made to coincide with the heating amount determined by the heating amount determining means, even if the heating amount is low enough to hinder the heat generation of the inverter circuit device, heat is actively generated inside the inner pot. It is possible to provide an induction-heated rice cooker that can generate convection and produce delicious rice with less uneven 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 control block diagram of the induction heating type rice cooker.

FIG. 3 is a heating state diagram of the induction-cooked rice cooker as rice cooks.

FIG. 4 is an operation flowchart of a main part of the induction heating type rice cooker.

FIG. 5 is a heating state diagram of a conventional induction heating type rice cooker as rice cooking proceeds.

[Explanation of symbols]

 4 Inverter circuit device 5 Inner pot 8 Heating amount adjustment means 9 Heating amount determination means 10 Judgment means

Claims (1)

(57) [Claims] An induction heating type rice cooker for induction heating a rice cooker (5) containing rice and water and cooking rice with a high frequency magnetic field generated from an induction heating coil (3) connected to an inverter circuit device (4). A heating amount adjusting means (8) for adjusting the heating amount for heating the inner pot (5) by changing the output of the inverter circuit device (4); Heating amount determining means (9) for determining an appropriate heating amount; and a heating amount adjusting means (8) when the heating amount determined by the heating amount determining means (9) is higher than a predetermined heating amount. If the heating amount is continuously determined by the heating amount determined by the determining means (9) and the heating amount determined by the heating amount determining means (9) is lower than the predetermined heating amount, it is determined to be intermittent heating in which ON-OFF is repeated. Means (10) Provided, this determination means (10)
When the intermittent energization is selected, the heating amount at the time of ON by the heating amount adjusting means (8) is ON time / (ON time + OFF time) with respect to the heating amount determined by the heating amount determining means (9).
Inner pot (5) even when the heating amount is low, with the reciprocal multiple of the ratio
An induction-cooked rice cooker characterized by sufficient internal convection of water.