JPH04231918A - Electromagnetic heating vessel - Google Patents

Abstract

PURPOSE:To uniformly heat the contents irrespective of its quantity by arranging plural heating coils extending from the bottom part to the side part on the outside surface of the heating vessel, selecting the heating coil in accordance with the quantity of the contents and executing the feed control of high frequency power. CONSTITUTION:In the center of the bottom part of a containing vessel 4, a sensor 5 for detecting whether a rice cooker 5 exists or not, and also, detecting the rice cooking quantity is placed. In the part corresponding to the bottom part of the rice cooker 3, a bottom coil LO for executing induction heating to its bottom part is provided, and in the part corresponding to the side part, horizontal coils L1-L5 for executing induction heating to its side part are arranged. To plural heating coils LO-L3, high frequency power from an inverter circuit part 7 controlled by a control signal from a control part 6 is supplied. The control part 6 supplies selectively a high frequency current to the bottom coil LO and the horizontal coils L1-L3, based on the rice cooking quantity detected by the sensor 5. When the high frequency power is supplied to the coils LO-L3, an overcurrent is generated in the rice cooker 3 by electromagnetic induction, the rice cooker is heated, and its contents are heated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic heating container such as a rice cooker, which is a cylindrical heating container with a bottom and is heated by high frequency electromagnetic induction heating.

0002

[Prior Art] A typical prior art is JP-A-2-1216
This is shown in Publication No. 08. This prior art relates to a rice cooker that uses electromagnetic induction heating, and is made of a cylindrical pot with a bottom made of a material with high relative magnetic permeability and resistivity, such as iron. Heating coils are arranged at each of the corner portions leading to the corner, and a high frequency current is supplied to each heating coil individually. The high-frequency magnetic field from the heating coil generates eddy currents in the pot, and the eddy currents generate heat in the pot, thereby heating its contents.

[0003] This configuration realizes uniform heating from the bottom of the pot, making it possible to cook rice evenly, and also by individually controlling the current supplied to each heating coil according to the amount of rice cooked. , I am trying to cook delicious rice by setting the appropriate heating amount according to the amount of rice to be cooked.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned prior art, heating is basically only performed from the bottom, so it is necessary to heat the pot relatively far from the bottom, especially when a large amount of rice is being cooked. Heating of the heated parts is not always done well. For this reason, the contents of the pot cannot be heated uniformly, which may result in uneven cooking.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electromagnetic heating container that solves the above-mentioned technical problems and can uniformly heat the contents of the heating container regardless of the amount of the contents. It is to be.

[0006]

[Means for Solving the Problems] The electromagnetic heating container of the present invention for achieving the above object is an electromagnetic heating container that heats the contents of the heating container by induction heating the heating container. , along the outer surface of the heating container,
A plurality of heating coils are arranged in an area extending from the bottom to the sides, and power supply control selects some or all of the plurality of heating coils to supply high-frequency power depending on the amount of contents in the heating container. means.

[0007]

[Operation] According to the above structure, a plurality of heating coils are arranged along the outer surface of the heating container from the bottom to the sides, and the power supply control means is controlled according to the amount of contents in the heating container. Since high-frequency power is supplied to some or all of the plurality of heating coils, heating can also be performed from the side of the heating container depending on the amount of contents in the heating container.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples will be explained in detail below with reference to the accompanying drawings showing examples. FIG. 1 is a sectional view showing the basic structure of an electromagnetic heating type rice cooker which is an embodiment of the electromagnetic heating container of the present invention. This rice cooker includes a cylindrical main body 1 and a lid 2 connected to the main body 1 by a hinge mechanism 9 so as to be openable and closable. Inside the main body 1, a storage container 4 is provided for removably housing a rice bowl 3, which is a cylindrical heating container with a bottom. The rice bowl 3 is made of a material with high resistivity and relative magnetic permeability, such as iron or stainless steel. A sensor 5 is arranged at the center of the bottom of the storage container 4 to detect the presence or absence of the rice bowl 3 and to detect the amount of cooked rice, which is the amount of the contents of the rice bowl 3. Detection of the amount of cooked rice is achieved, for example, by detecting the slope of the temperature rise curve of the rice bowl 3 or by detecting the weight of the rice bowl 3 containing the contents.

A bottom coil L0, which is a heating coil for induction heating the bottom of the rice bowl 3, is provided on the outside of the storage container 4 at a portion corresponding to the bottom of the rice bowl 3. Further, on the outside of the storage container 4 and at a portion corresponding to the side of the rice bowl 3, horizontal coils L1, L2, and L3, which are heating coils for induction heating the side of the rice bowl 3, are installed from below. They are arranged in order. In this way, the plurality of heating coils L0, L1, L2, L3 arranged along the outer surface of the storage container 4 in a region extending from the bottom to the side of the rice bowl 3 include:
High frequency power is supplied from an inverter circuit section 7 controlled by a control signal from a control section 6 . Note that the output of the sensor 5 described above is given to the control unit 6, and the supply of high frequency power is prevented when the rice bowl 3 is not set. 10 is a fan for cooling the inverter circuit section 7.

When high frequency power is supplied to the coils L0, L1, L2, L3, an eddy current is generated in the rice cooker 3 by electromagnetic induction due to the high frequency magnetic field generated by the coils L0, L1, L2, L3, and this eddy current As a result, the rice bowl 3 generates heat. The heat generated in the rice bowl 3 heats its contents. FIG. 2 is an electrical circuit diagram showing the electrical configuration of the electromagnetic heating rice cooker. Power from the commercial AC power supply 20 is rectified by a rectifier 21, smoothed by a choke coil 22 and a smoothing capacitor 23, and then supplied to coils L0, L1, L2, and L3 connected in parallel. Connected between the bottom coil L0 and the rectifier 21 is an inverter circuit I0 constituted by a parallel circuit of a power element P0 including a transistor Q0 and a reverse current diode D0, and a resonant capacitor C0. Transistor Q0 is turned on/off at predetermined cycles by a control signal from control section 6. The horizontal coils L1, L2, and L3 have similar configurations, and the respective portions corresponding to the configuration regarding the bottom coil L0 are shown with the same alphabet followed by the suffixes 1, 2, and 3 of each coil. Each coil L0, L1
, L2, and L3 are independently controlled by the control section 6.

Transistor Q0 corresponding to bottom coil L0
When turned on, current flows from the bottom coil L0 through the transistor Q0. From this state, when the transistor Q0 is turned off, the current flowing through the bottom coil L0 begins to charge the resonant capacitor C0. By discharging the charged resonance capacitor C0, a current in the opposite direction begins to flow through the bottom coil L0. This current in the reverse direction suddenly becomes 0 even after the voltage between both terminals of the resonant capacitor C0 becomes 0.
diode D in power element P0
flows through 0. In this way, a high frequency current is supplied to the bottom coil L0. Horizontal coil L1, L
The operations regarding 2 and L3 are also similar.

The control unit 6 controls the bottom coil L0 and the horizontal coils L1, L2, based on the amount of cooked rice detected by the sensor 8.
A high frequency current is selectively supplied to L3. That is, when the amount of rice to be cooked is small as shown in FIG. 3, a control signal is given only to the transistor Q0 in order to supply high frequency current only to the bottom coil L0, and the transistors Q1 and Q2 corresponding to the remaining coils L1, L2, and L3 are supplied with a control signal. , Q3 are not given a control signal. Similarly, when the amount of rice cooked is medium as shown in FIG. 4, the high frequency current is supplied only to the bottom coil L0 and the horizontal coil L1, and when the amount of rice cooked is large as shown in FIG. A high frequency current is supplied to all of the horizontal coils L1, L2, and L3.

[0013] In the rice cooker 3, eddy currents are generated near the coil to which the high frequency current is supplied, and the rice cooker 3 is
Since the contents of the rice cooker will be heated, the bottom coil L0 and horizontal coils L1, L2 corresponding to the amount of rice cooked as described above are used.
, L3, the contents of the rice bowl 3 can be uniformly heated from an appropriate heat source position. In this way, in this embodiment, a plurality of heating coils L0, L1, L2, and L3 are arranged side by side in the area extending from the bottom to the side of the rice cooker 3, and power is supplied to each heating coil in accordance with the amount of rice cooked. Since this is done, the contents of the rice bowl 3 can be uniformly heated according to the amount of rice to be cooked, and delicious rice can be cooked. Moreover, since the high-frequency current is supplied to some or all of the bottom coil L0 and the horizontal coils L1, L2, and L3 depending on the amount of rice to be cooked, unnecessary power consumption does not occur.

FIG. 6 is an electrical circuit diagram showing the electrical configuration of another embodiment of the present invention. In FIG. 6, parts corresponding to those shown in FIG. 2 described above are given the same reference numerals. In this embodiment, the bottom coil L0 and the horizontal coils L1, L2, L3 are all connected in series, and each coil L0, L1, L2, L3 is connected to a parallel circuit of an inverter circuit I0 and a resonant capacitor C0, respectively. Relays R0, R1, R2, and R3 are provided. The control unit 6 conducts any one of the relays R0, R1, R2, and R3 based on the amount of cooked rice detected by the amount of cooked rice sensor 8. That is, when the amount of cooked rice is small, the relay R0 is made conductive, when the amount of cooked rice is medium, the relay R2 is made conductive, and when the amount of cooked rice is large, the relay R3 is made conductive. Thereby, it is possible to realize a heating state corresponding to the amount of cooked rice using one inverter circuit I0 and one resonant capacitor C0, which is advantageous for cost reduction.

Further, the output P of the coil is expressed as P=A×(I·L) 2 (where A is a constant), where I is the current flowing through the coil and L is the self-inductance of the coil. Therefore, if the amount of rice cooked is large, the more coils are connected in series as described above, the overall self-inductance will increase as the amount of rice cooked increases, so it will be possible to obtain a higher output as the amount of rice cooked increases. can. As a result, it is possible to provide an output corresponding to the amount of rice to be cooked, perform good heating, and cook delicious rice.

It should be noted that the present invention is not limited to the above embodiments. For example, in the above embodiment, one bottom coil and three horizontal coils are provided, but the bottom coil may be divided into two or more, and the number of horizontal coils may be It may be one piece, or it may be a plurality of pieces other than three pieces. Furthermore, in the above embodiment, the heating coils L0 to L1 are arranged outside the storage container 4 that stores the rice bowl 3, but the heating coils are arranged on the outer surface of the rice bowl 3 without using the storage container 4. You may.

Furthermore, a temperature sensor may be provided to detect the temperature of the rice cooker 3 during rice cooking, and power may be selectively supplied to the heating coils L0 to L3 in accordance with the output of this temperature sensor. Further, a configuration may be adopted in which the amount of power supplied to each of the coils L0 to L3 can be changed discretely or continuously.

Furthermore, in the above embodiment, the amount of cooked rice is automatically detected by the sensor 5, but the amount of cooked rice is input by the operator, and the control section 6 controls the amount of cooked rice according to the inputted amount of cooked rice. The supply of high frequency current to the coils L0 to L3 may be controlled. In addition, in the above example,
Although the explanation has been given using a rice cooker as an example, the present invention can be widely implemented in electromagnetic heating containers other than rice cookers.

Various other design changes can be made without changing the gist of the present invention.

[0020]

As described above, according to the electromagnetic heating container of the present invention, heating is also performed from the side of the heating container depending on the amount of contents in the heating container. As a result, the contents can be heated uniformly regardless of the amount of contents in the heating container.
Good heating conditions can be achieved. Furthermore, since high-frequency power is supplied to some or all of the heating coils depending on the amount of contents in the heating container, no unnecessary power consumption occurs.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the basic configuration of an electromagnetic heating type rice cooker which is an embodiment of the electromagnetic heating container of the present invention.

FIG. 2 is an electric circuit diagram showing the electrical configuration of the electromagnetic heating rice cooker.

FIG. 3 is a cross-sectional view for explaining the relationship between the amount of rice cooked and the power supply status to the heating coil.

FIG. 4 is a cross-sectional view for explaining the relationship between the amount of cooked rice and the state of power supply to the heating coil.

FIG. 5 is a cross-sectional view for explaining the relationship between the amount of rice cooked and the power supply status to the heating coil.

FIG. 6 is an electrical circuit diagram showing the electrical configuration of another embodiment of the present invention.

[Explanation of symbols]

3. Rice bowl (heating container) 5 Sensor 6 Control unit (power supply control means) 7 Inverter circuit section L0 bottom coil L1 horizontal coil L2 horizontal coil L3 horizontal coil I0 Inverter circuit I1 Inverter circuit I2 Inverter circuit I3 Inverter circuit R0 Relay R1 Relay R2 Relay R3 Relay

Claims (1)

[Claims] Claims: 1. An electromagnetic heating container that heats the contents of the heating container by induction heating the heating container, wherein the heating container is arranged in an area extending from the bottom to the side along the outer surface of the heating container. an electromagnetic device comprising: a plurality of heating coils; and a power supply control means that selects some or all of the plurality of heating coils and supplies high-frequency power to the heating coils according to the amount of contents in the heating container. heating container.