JP5103782B2 - rice cooker - Google Patents

Description

  The present invention relates to a rice cooker that heats a pan by induction heating.

  Conventionally, rice cookers have generated a high-frequency magnetic field by flowing a high-frequency current through a heating coil in order to heat the pan, and this high-frequency magnetic field has generated an eddy current on the surface of the pan. However, a part of the energy of the magnetic field becomes a leakage magnetic field leaking to the outside, and it has been reported that the leakage magnetic field has an unfavorable effect on the human body.

In order to effectively reduce the leakage magnetic field in the low-frequency region among these leakage magnetic fields, the heating coil portion in which the heating coil is spirally wound, and the coil connected in series on the outer peripheral side of the coil and the coil There has been proposed a configuration in which a magnetic field leaking to the outside is reduced by configuring it with a leakage magnetic field canceling coil portion that is wound in the reverse direction and flows a reverse current (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-335057

  However, in the above-described conventional configuration, it is necessary to provide a leakage magnetic field canceling coil that allows a reverse current to flow in order to reduce the leakage magnetic field generated from the bottom heating coil and the bottom heating coil.

  At this time, if the distance between the heating coil portion and the leakage magnetic field canceling coil is too close, the magnetic fields generated from the respective coils are reversed, so the magnetic fields for heating the pans cancel each other. Therefore, the leakage magnetic field canceling coil portion does not contribute to the heating of the pan, but conversely reduces the heating efficiency.

  In addition, in order to arrange the leakage magnetic field canceling coil so as not to cancel the magnetic field that heats the pan, it is necessary to secure a certain distance from each heating coil part, and there is a problem that the outer shape of the rice cooker becomes large. Was.

The present invention solves the above-mentioned conventional problems, and does not increase the outer shape of the rice cooker, and does not lower the heating efficiency of the outer peripheral part of the pan and the inner peripheral part of the pan. It aims at reducing the leakage magnetic field of the low frequency area | region which generate | occur | produces from a coil.

In order to achieve the above object, the present invention accommodates a pot for putting rice and water into the inside of a rice cooker body, and heats the bottom outer periphery of the pot with a bottom outside heating coil having a first group of magnetic bodies. The bottom inner circumference of the base plate is heated by a bottom inner heating coil having a second magnetic body group, and a high frequency current is supplied to the outer bottom heating coil and the bottom inner heating coil by an inverter circuit. The AC power source is rectified and provided with a power supply having a frequency that is approximately twice that of the AC power source, and the outer bottom heating coil is disposed at a higher position than the bottom inner heating coil , and the end portions of the two magnetic substance groups The distance between the inner periphery of the outer bottom heating coil and the outer periphery of the inner heating coil is separated from the distance between the outer outer heating coil and the pan or the distance between the inner heating coil and the pan so that the high-frequency magnetic fluxes coming out from each other are not canceled out. Heating coil outside the bottom and heating coil inside the bottom Preparative connected in series, and to be able to leak the magnetic field of low frequency generated by the heating coil cancels, in a direction opposite the direction of flow of the high-frequency current flowing through the high-frequency current and bottom heating coil flowing through the bottom outside heating coil It is connected so that it becomes.

  Thereby, since the low frequency leakage magnetic field generated from the adjacent heating coils is reversed, the low frequency leakage magnetic fields cancel each other. Also, the height of the outside heating coil and the inside heating coil are different, and the distance between the two heating coils and the pan is closer than the distance between the two heating coils. Since the high frequency magnetic field can be applied to the pan before the high frequency magnetic field is canceled, it is not necessary to reduce the heating efficiency.

  In the rice cooker of the present invention, the outside heating coil and the inside heating coil cancel each other's low frequency leakage magnetic field, so a new leakage magnetic field canceling coil is not required, and the outer shape is not enlarged. The low frequency leakage magnetic field can be reduced without lowering the heating efficiency of the pot outer periphery and the pot inner periphery.

1st invention has the rice cooker main body, the pot accommodated in the inside of the said rice cooker main body, and the rice which puts water with water, and the 1st magnetic body group which heats the bottom outer periphery of the said pot, 1st out-of-bottom heating A coil, an in- bottom heating coil having a second magnetic body group for heating the inner circumference of the pan, an inverter circuit for supplying a high-frequency current to the out-of-bottom heating coil and the in-bottom heating coil, and an AC power source When the inverter circuit rectifies the AC power supply, and a power supply having a substantially twice the low-frequency frequency of the AC power source, placing the bottom outer heating coil at a position higher than the bottom heating coils, wherein The distance between the inner periphery of the outer bottom heating coil and the outer periphery of the inner heating coil is the distance between the outer heating coil and the pan so that the high-frequency magnetic flux emitted from the ends of the two magnetic groups is not canceled out. Or away from the distance between the bottom heating coil and the pan And connecting said bottom heating coil and the bottom outer heating coil in series, and the high-frequency current flowing through the bottom outer heating coil so as to be able to leak the magnetic field of low frequency generated by the heating coil cancels the said bottom heating Even if electric power having a frequency component twice that of the AC power supply is supplied from the power supply, the bottom outside heating coil and the bottom inside heating coil are connected so that the direction of the high-frequency current flowing through the coil is reversed. Since the low-frequency leakage magnetic field generated from each other is reversed, the mutual low-frequency leakage magnetic fields can be canceled out, and a leakage magnetic field canceling coil is not required. Also, by shifting the height of the outside bottom heating coil and the bottom heating coil, the distance between the pan and the outside heating coil and the pot and the inside heating coil is made closer than the distance between the outside heating coil and the inside heating coil, The high frequency magnetic field can be supplied to the pan before the high frequency magnetic fields of the outside bottom heating coil and the inside bottom heating coil cancel each other. Accordingly, the low frequency leakage magnetic field can be reduced without increasing the outer shape and lowering the heating efficiency.

2nd invention is a rice cooker main body, the pot accommodated in the inside of the said rice cooker main body, and the rice which puts water and water, the bottom outside heating coil with the 1st magnetic body group which heats the bottom outer periphery of the said pan, A bottom heating coil having a second magnetic body group for heating the bottom inner circumference of the pan, an inverter circuit for supplying a high frequency current to the outside heating coil and the bottom heating coil, an AC power source, It rectifies the AC power to the inverter circuit, and a power supply having a substantially twice the low-frequency frequency of the AC power source, comprising a, placing the bottom outer heating coil at a position higher than the bottom heating coils, wherein The distance between the inner periphery of the outer bottom heating coil and the outer periphery of the inner heating coil is the distance between the outer heating coil and the pan so that the high-frequency magnetic flux emitted from the ends of the two magnetic groups is not canceled out. Or the distance between the heating coil in the bottom and the pan , The bottom outer heating coil and the bottom heating coils connected in parallel, and a high-frequency current flowing through the bottom outer heating coil so as to be able to leak the magnetic field of low frequency generated by the heating coil cancels said bottom It is connected so that the flow direction of the high-frequency current flowing through the heating coil is reversed, and even if power having a frequency component twice that of the AC power supply is supplied from the power supply, the bottom outside heating coil and the bottom heating Since the low-frequency leakage magnetic fields generated from the coils are reversed, it is possible to cancel each other's low-frequency leakage magnetic fields, and no leakage magnetic field canceling coil is required. Also, by shifting the height of the outside bottom heating coil and the bottom heating coil, the distance between the pan and the outside heating coil and the pot and the inside heating coil is made closer than the distance between the outside heating coil and the inside heating coil, The high frequency magnetic field can be supplied to the pan before the high frequency magnetic fields of the outside bottom heating coil and the inside bottom heating coil cancel each other. Moreover, by connecting the outside bottom heating coil and the inside bottom heating coil in parallel, the current flowing through each heating coil can be suppressed, and the loss of the heating coil can be reduced. Therefore, it is possible to increase the heating efficiency and reduce the low frequency leakage magnetic field without increasing the outer shape.

  According to a third invention, in the first or second invention, a plurality of first magnetic bodies arranged radially on the outside heating coil and a plurality of second magnets arranged radially on the inside heating coil. The first magnetic body group and the second magnetic body group are arranged so that their end portions face each other, and the high-frequency magnetic field generated from each heating coil is the other heating coil. Can be suppressed by the magnetic material, and the magnetic flux concentrates on the end of the magnetic material, so that the number of hot points can be increased and the convection necessary for rice cooking can be reduced.

  According to a fourth invention, in the first or second invention described above, a plurality of first magnetic bodies arranged radially on the outside heating coil and a plurality of second magnets arranged radially on the inside heating coil. The first magnetic body group and the second magnetic body group are arranged so that their end portions do not face each other, and a high-frequency magnetic field generated from each heating coil is applied to the other heating coil. Leakage can be suppressed by the magnetic material, and the magnetic flux concentrates on the end of the magnetic material, so that the number of points at which the temperature becomes high can be increased and the convection necessary for cooking rice can be reduced.

  A fifth invention is the invention according to any one of the first to fourth inventions, wherein the number of turns of the outside bottom heating coil is less than the number of turns of the inside bottom heating coil, which is less than the inside heating coil that is difficult to be exposed to the human body. It is possible to reduce the high-frequency leakage magnetic field from the outside bottom heating coil that is easily exposed to the human body, and to suppress the low-frequency leakage magnetic field.

  The sixth invention is the invention according to any one of the first to fifth inventions, wherein the low frequency inductance value of the outer bottom heating coil and the low frequency inductance value of the inner bottom heating coil are substantially the same, The leaking low frequency leakage magnetic field can be made substantially zero.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1: shows sectional drawing of the rice cooker in Embodiment 1 of this invention, and FIG. 2 shows the principal part circuit diagram made into the block of the rice cooker.

  As shown in FIG. 1, the rice cooker main body 1 is provided with a pan storage portion 3 that can detachably store a pan 2 into which rice and water are put, and a side portion of the pan 2 is placed outside the pan storage portion 3. The bottom heating coil 4 wound in a spiral shape is disposed so as to face the bottom, and the bottom heating coil 5 wound in a spiral shape is disposed so as to face the bottom surface portion of the pan 2. The bottom portion of the pan 2 is induction-heated by a magnetic field generated from the coil 4 and the bottom heating coil 5. When viewed from the top of the rice cooker body 1 (in the direction of the opening of the coil), the winding center of the outer bottom heating coil 4 and the winding center of the inner heating coil 5 are arranged substantially the same. The outside bottom heating coil 4 and the inside bottom heating coil 5 are connected in series as shown in FIG.

  A ferrite 6 constituting the first magnetic body group is arranged outside the outside bottom heating coil 4, and a ferrite 7 constituting the second magnetic body group is arranged outside the inside bottom heating coil 5. While suppressing the leakage magnetic field leaking from the coil, the magnetic flux is concentrated on the ends of the ferrite 6 and the ferrite 7.

  FIG. 5 shows the positional relationship between the outside bottom heating coil 4, the inside bottom heating coil 5 and the ferrites 6, 7 from the bottom of the rice cooker. As shown in FIG. 5, four ferrites 6 are arranged radially on the outside bottom heating coil 4, and four ferrites 7 are arranged radially on the inside bottom heating coil 5. These end portions are arranged so as to face each other.

  The top opening of the rice cooker main body 1 is provided with an outer lid 8 that can be freely opened and closed so that the pan 2 can be attached and detached. In the lower part of the rice cooker main body 1, as shown in FIG. 2, a heating substrate 9 on which a bottom inverter circuit (inverter circuit) 24 for supplying a high frequency current to the outside bottom heating coil 4 and the inside bottom heating coil 5 is arranged. is doing. Further, inside the outer lid 8, a control board 10 on which a control circuit 25 that controls the bottom inverter circuit 24 and operation keys that operate the rice cooker are mounted.

  Further, as shown in FIG. 1, the outside bottom heating coil 4 is arranged at a position higher than the inside bottom heating coil 5, and the distance A between the inner periphery of the outside bottom heating coil 4 and the outer periphery of the bottom inside heating coil 5 is the bottom. It is separated from the distance B between the outer heating coil 4 and the pan 2 or the distance C between the bottom heating coil 5 and the pan 2.

  As shown in FIG. 2, when the rice cooker body 1 is connected to a commercial power source 21, DC power is supplied to the bottom inverter circuit 24 via a full-wave rectifier 22 and a capacitor 23 mounted on the heating substrate 10. The bottom inverter circuit 24 is connected to a series circuit of the outside bottom heating coil 4 and the inside bottom heating coil 5, and the bottom inverter circuit 24 supplies the high frequency current IL 1 to the outside bottom heating coil 4 and the inside bottom heating coil 5.

  Here, the bottom heating coil 4 and the bottom heating coil 5 indicate the direction in which the rice cooker body 1 is wound when viewed from above. That is, the out-of-bottom heating coil 4 is wound so that the high-frequency current IL1 flows clockwise. Further, the bottom heating coil 5 is wound so that the high-frequency current IL1 flows counterclockwise. Further, the number of turns of the outside bottom heating coil 4 is smaller than the number of turns of the inside bottom heating coil 5, and the low frequency inductance value of the outside bottom heating coil 4 and the low frequency inductance value of the inside bottom heating coil 5 are made substantially the same. .

  The control circuit 24 mounted on the control board 10 controls the energization state and the oscillation frequency of the bottom inverter circuit 24 on the heating board 9.

3 shows waveforms of main parts, FIG. 3 (a) shows the voltage waveform of the commercial power source 21, FIG. 3 (b) shows the waveform of the voltage across the capacitor 23 when the bottom inverter circuit 24 is operated, and FIG. (C) is an envelope waveform of the high-frequency current IL1. In the present embodiment, the capacitance of the capacitor 23 is small and only smoothes high frequency components. Therefore, the power supplied to the bottom inverter circuit 24 has a frequency about twice that of the commercial power supply 21, and the high-frequency current IL 1 flowing through the bottom outside heating coil 4 and the bottom inside heating coil 5 is It also has about twice the frequency component, and a magnetic field having a frequency about twice that of the commercial power source 21 of the outside heating coil 4 and the inside heating coil 5 is generated. Since this magnetic field has a low frequency, it does not contribute to heating of the pan 2 and becomes a leakage magnetic field.

  FIG. 4 shows frequency characteristics of the inductance value and the resistance value when the pan 2 is placed on the heating coil. Curve (a) shows the inductance value, and curve (b) shows the resistance value. As shown in FIG. 4, as the frequency increases, the inductance value decreases and the resistance value increases. That is, the high-frequency magnetic field can heat the pan 2, but the low-frequency magnetic field cannot heat the pan 2, resulting in a leakage magnetic field.

  The operation and action of the above configuration will be described. When the pan 2 is set at a predetermined position of the rice cooker body 1 and the operation keys are operated, the control circuit 25 controls the operation of the bottom inverter circuit 24 so as to heat the pan 2 based on a preset rice cooking sequence. To do.

  When controlling the heating of the pan 2, the control circuit 25 sends a drive signal to the bottom inverter circuit 24, and the bottom inverter circuit 24 supplies the high frequency current IL1 to the outside bottom heating coil 4 and the inside bottom heating coil 5. At this time, the high-frequency current IL1 flows in the clockwise direction when viewed from the top of the rice cooker body 1 in the out-bottom heating coil 4, and flows counterclockwise in the bottom heating coil 5 when viewed from the top of the rice cooker body 1.

  That is, the same current flows in the out-of-bottom heating coil 4 and the in-bottom heating coil 5, and the magnetic field generated in the out-of-bottom heating coil 4 and the magnetic field generated in the in-bottom heating coil 5 are in opposite directions. Therefore, it is possible to reduce the leakage magnetic field leaking outside the rice cooker body 1 by canceling out the magnetic fields generated from each other.

  At this time, before the high-frequency magnetic field of the bottom outside heating coil 4 and the high-frequency magnetic field of the bottom-inside heating coil 5 cancel each other, the inner peripheral portion of the bottom-outside heating coil 4 and the bottom-inside heating are supplied so that the high-frequency magnetic field is supplied to the pan 2. The distance A of the outer peripheral portion of the coil 5 is separated from the distance B between the outside-bottom heating coil 4 and the pan 2 or the distance C between the inside-bottom heating coil 5 and the pan 2. Furthermore, since the path of the high frequency magnetic field is shifted by placing the outside bottom heating coil 4 higher than the inside heating coil 5, the high frequency magnetic field is efficiently supplied to the pan 2.

  In addition, as shown in FIG. 5, the ferrite 6 is disposed outside the bottom heating coil 4 and the ferrite 7 is disposed outside the bottom heating coil 5. Therefore, the leakage of the magnetic field to the in-bottom heating coil 5 can be suppressed. Further, the magnetic flux of the inner bottom heating coil 5 passes through the ferrite 7, and the leakage of the magnetic field to the outer bottom heating coil 6 can be suppressed.

  Therefore, the outside bottom heating coil 4 and the inside bottom heating coil 5 generate high-frequency magnetic fields in opposite directions, but can supply the high-frequency magnetic field to the pan 2 without canceling each other. At the same time, the magnetic flux concentrates on the end portion of the ferrite 6 and the end portion of the ferrite 7, so that the portion of the pan 2 facing the end portion of the ferrite 6 and the end portion of the ferrite 7 is intensively heated. Since the high temperature point can be increased more than when the outer bottom heating coil 4 and the inner bottom heating coil 5 are wound in the same direction, fine convection can be realized and heat can be efficiently transmitted to the rice.

  Further, by reducing the number of turns of the outer bottom heating coil 4 close to the side surface and the upper surface of the rice cooker to be less than the number of turns of the inner heating coil 5, the leakage magnetic fields on the upper surface side and the side surface on which humans are easily exposed to the magnetic field can be reduced. A rice cooker that can be suppressed and safe for the human body can be provided.

Further, by making the inductance value of the outer bottom heating coil 4 and the inductance value of the inner bottom heating coil 5 substantially the same at a low frequency, that is, twice the frequency of the commercial power source 21, as described in FIG. In a low frequency region such as twice the frequency of 21 (100 Hz and 120 Hz in Japan), the magnetic field does not contribute to the heating of the pan 2 and becomes a leakage magnetic field. If the inductance value of the bottom heating coil 5 is made substantially the same, and the current flowing through the heating coil in the series connection is also made the same, the low-frequency magnetic fields generated from the two heating coils will be almost the same, and cancel each other's magnetic field. Thus, the low frequency leakage magnetic field becomes almost zero. Therefore, a rice cooker safe for the human body can be provided.

  As described above, in the present embodiment, the out-of-bottom heating coil 4 is arranged at a position higher than the in-bottom heating coil 5, and the distance between the inner periphery of the out-of-bottom heating coil 4 and the outer periphery of the in-bottom heating coil 5. A is separated from the distance B between the outside heating coil 4 and the pan 2, or the distance C between the inside heating coil 5 and the pan 2, the outside heating coil 4 and the inside heating coil 5 are connected in series, and outside the bottom. Since the high-frequency current flowing in the heating coil 4 and the high-frequency current flowing in the bottom heating coil 5 are connected in opposite directions, the low-frequency leakage magnetic field generated from the bottom bottom heating coil 4 and the bottom heating coil 5 is reduced. Since the directions are opposite to each other, it is possible to cancel each other's low-frequency leakage magnetic field, and no leakage magnetic field canceling coil is required. Further, the heights of the outer bottom heating coil 4 and the bottom heating coil 5 are shifted, and the pot 2, the outer bottom heating coil 4, the pot 2, the inner heating coil, and the distance between the outer bottom heating coil 4 and the inner heating coil 5 are shifted. By making the distance 5 closer, the high frequency magnetic field can be supplied to the pan 2 before the high frequency magnetic fields of the outer bottom heating coil 4 and the inner bottom heating coil 5 cancel each other. Accordingly, the low frequency leakage magnetic field can be reduced without increasing the outer shape and lowering the heating efficiency.

  Moreover, it is provided with a plurality of ferrites 6 arranged radially on the outside heating coil 4 and a plurality of ferrites 7 arranged radially on the inside heating coil 5, and the ends of the ferrite 6 and the ferrite 7 face each other. Since the ferrites 6 and 7 can suppress the high-frequency magnetic field generated from each heating coil from leaking to the other heating coil, the magnetic flux concentrates on the ends of the ferrites 6 and 7. Can be increased, and the convection necessary for cooking rice can be reduced.

  Further, since the number of turns of the outside bottom heating coil 4 is smaller than the number of turns of the inside bottom heating coil 5, the high frequency leakage magnetic field from the outside bottom heating coil 4 that is more easily exposed to the human body than the inside heating coil 5 that is hard to be exposed to the human body is reduced. It is also possible to reduce the leakage magnetic field at a low frequency.

  Moreover, since the low frequency inductance value of the outside bottom heating coil 4 and the low frequency inductance value of the inside bottom heating coil 5 are made substantially the same, the leaking low frequency leakage magnetic field can be made substantially zero.

  In the present embodiment, the outside bottom heating coil 4 is wound so that the high-frequency current IL1 flows clockwise, and the bottom heating coil 5 is wound so that the high-frequency current IL1 flows counterclockwise. Even if each heating coil is wound in the opposite direction so that the high-frequency current flows in the opposite direction, the same effect is obtained.

(Embodiment 2)
FIG. 6: shows the principal part circuit diagram which made the rice cooker in Embodiment 2 of this invention a part block.

  As shown in FIG. 6, the bottom inverter circuit 24 is connected to a parallel circuit of the outside bottom heating coil 4 and the inside bottom heating coil 5, and the bottom inverter circuit 24 supplies a high frequency current IL2 to the outside bottom heating coil 4, A high frequency current IL3 is supplied to the inner heating coil 5.

Here, the bottom heating coil 4 and the bottom heating coil 5 indicate the direction in which the rice cooker body 1 is wound when viewed from above. That is, the outside bottom heating coil 4 is wound so that the high-frequency current IL2 flows clockwise. The high frequency current IL3 is wound around the bottom heating coil 5 so as to flow counterclockwise. Other configurations are the same as those of the first embodiment.

  The operation and action of the above configuration will be described. When the pan 2 is set at a predetermined position on the rice cooker body 1 and the operation keys are operated, the control circuit 25 operates the bottom inverter circuit 24 so as to heat the bottom portion of the pan 2 based on a preset rice cooking sequence. To control. The bottom inverter circuit 24 receives a signal from the control circuit 25 and supplies the high frequency current IL2 to the outside heating coil 4 and supplies the high frequency current IL3 to the inside heating coil 5.

  At this time, the high frequency current IL2 flows clockwise when the outside heating coil 4 is viewed from the top of the rice cooker body 1, and the high frequency current IL3 flows counterclockwise when the bottom heating coil 5 is viewed from the top of the rice cooker body 1. . That is, the current IL2 flowing through the out-of-bottom heating coil 4 and the current IL3 flowing through the in-bottom heating coil 5 flow in opposite directions, and the magnetic field generated by the out-of-bottom heating coil 4 and the magnetic field generated by the in-bottom heating coil 5 are Since it becomes a reverse direction, the magnetic field which mutually generate | occur | produces is canceled and the leakage magnetic field which leaks outside the rice cooker main body 1 is reduced.

  At the same time, in the present embodiment, by connecting the outside-bottom heating coil 4 and the inside-bottom heating coil 5 in parallel, the high-frequency current is divided into IL2 and IL3, so that the current flowing through one heating coil can be reduced, Since the self-heating of the coil is reduced, a low-loss rice cooker can be realized.

  As described above, in the present embodiment, the outer bottom heating coil 4 and the inner bottom heating coil 5 are connected in parallel, and the high frequency current IL2 and the high frequency current IL3 are wound in opposite directions. The respective low frequency leakage magnetic fields can be canceled out, and a new coil for canceling the leakage magnetic field is not required. Moreover, by connecting the outside bottom heating coil 4 and the inside bottom heating coil 5 in parallel, the current flowing through each heating coil can be suppressed, and the loss of the heating coil can be reduced. Therefore, it is possible to increase the heating efficiency and reduce the low frequency leakage magnetic field without increasing the outer shape.

  In the present embodiment, the bottom heating coil 4 is wound so that the high-frequency current IL2 flows clockwise, and the bottom heating coil 5 is wound so that the high-frequency current IL3 flows counterclockwise. Even if each heating coil is wound in the opposite direction so that the high-frequency current flows in the opposite direction, the same effect is obtained.

(Embodiment 3)
FIG. 7 shows the positional relationship between the heating coil and the magnetic body group of the rice cooker in Embodiment 3 of the present invention. In addition, FIG. 7 has shown the state which looked up at the heating coil from the rice cooker lower part.

  As shown in FIG. 7, the four ferrites 71 constitute a first magnetic body group and are arranged radially on the out-of-bottom heating coil 4, and the four ferrites 72 constitute a second magnetic body group to form an inner bottom. The heating coil 5 is arranged radially, and the end portions of the ferrite 71 and the ferrite 72 are arranged so as not to face each other. Other configurations are the same as those in the first or second embodiment.

  The operation in the above configuration will be described. The ferrite 71 is arranged radially on the outer bottom heating coil 4, the ferrite 72 is arranged radially on the inner bottom heating coil 5, and the ends of the ferrite 71 and the ferrite 72 are arranged so as not to face each other. In addition to suppressing the leakage magnetic field of each heating coil so as not to cancel the magnetic field from the other heating coil, the portion where the magnetic flux is concentrated most at the ferrite end can be formed with a small number of ferrites. Because it creates a lot of convection, it can efficiently transfer heat to rice.

  As described above, in the present embodiment, the ferrite 71 and the ferrite 72 are arranged so that the ends thereof are not opposed to each other, so that the high-frequency magnetic field generated from each heating coil leaks to the other heating coil. While being able to suppress by a body, since magnetic flux concentrates on the edge part of the ferrite 71 and 72, the point which becomes high temperature can be increased and the convection required for rice cooking can be made fine.

  As described above, the rice cooker according to the present invention eliminates the need for a new leakage magnetic field canceling coil because the outer bottom heating coil and the bottom heating coil cancel each other's low-frequency leakage magnetic field, and the outer shape is reduced. Since the low frequency leakage magnetic field can be reduced without increasing the heating efficiency of the pot outer peripheral part and the pot inner peripheral part, it is useful as a rice cooker for heating the pot by induction heating.

Sectional drawing of the rice cooker in Embodiment 1 of this invention. Main part circuit diagram of the rice cooker partially block Waveform diagram of the main part of the rice cooker Frequency characteristics diagram of inductance value and resistance value when a pan is placed on the heating coil of the rice cooker Arrangement relation diagram of bottom heating coil and magnetic substance group of rice cooker Part of the circuit diagram of the rice cooker according to Embodiment 2 of the present invention Arrangement relation diagram of bottom heating coil and magnetic substance group of rice cooker in embodiment 3 of the present invention

DESCRIPTION OF SYMBOLS 1 Rice cooker main body 2 Pan 4 Outside heating coil 5 Inside heating coil 24 Bottom inverter circuit (inverter circuit)

Claims (6)

A rice cooker body, a pot for storing rice and water stored in the rice cooker body, a first outside heating coil having a first magnetic body group for heating the bottom outer periphery of the pot, and the pot A bottom heating coil having a second magnetic body group for heating the bottom inner periphery, an inverter circuit for supplying a high frequency current to the outside heating coil and the bottom heating coil, an AC power source, and the inverter circuit An AC power supply is rectified, and a power supply having a frequency that is approximately twice as low as that of the AC power supply is provided, and the outer bottom heating coil is arranged at a position higher than the inner bottom heating coil , The distance between the inner peripheral part of the outer bottom heating coil and the outer peripheral part of the inner heating coil is the distance between the outer heating coil and the pan or the inner heating coil so that the high-frequency magnetic fluxes coming from the ends are not canceled out from each other. Heated outside the bottom away from the distance between the pan and RF flowing yl and the said bottom heating coils connected in series, and the high-frequency current flowing through the bottom outer heating coil so as to be able to leak the magnetic field of low frequency generated by the heating coil cancels said bottom heating coil Rice cooker connected so that the direction of current flow is reversed. A rice cooker body, a pot for storing rice and water stored in the rice cooker body, a bottom outer heating coil having a first magnetic body group for heating the bottom outer periphery of the pot, and a bottom inner periphery of the pot An inner bottom heating coil having a second magnetic body group for heating the inverter, an inverter circuit for supplying a high frequency current to the outer bottom heating coil and the inner heating coil, an AC power source, and an AC power source for the inverter circuit Rectifying and including a power supply having a frequency that is approximately twice as low as that of the AC power supply, the outer heating coil being arranged at a position higher than the inner heating coil, and the two magnetic substance groups The distance between the inner peripheral part of the outer bottom heating coil and the outer peripheral part of the inner heating coil is the distance between the outer heating coil and the pan or the inner heating coil so that the high-frequency magnetic fluxes coming from the ends are not canceled out from each other. Away from the distance between the pan and the bottom RF flowing the coil and the bottom heating coils connected in parallel, and a high-frequency current flowing through the bottom outer heating coil so as to be able to leak the magnetic field of low frequency generated by the heating coil cancels said bottom heating coil Rice cooker connected so that the direction of current flow is reversed. A plurality of first magnetic bodies arranged radially on the outside heating coil; and a plurality of second magnetic bodies arranged radially on the inside heating coil; 3. The rice cooker according to claim 1, wherein the magnetic body group is arranged so that the end portions thereof face each other. A plurality of first magnetic bodies arranged radially on the outside heating coil; and a plurality of second magnetic bodies arranged radially on the inside heating coil; The rice cooker according to claim 1 or 2, wherein the magnetic body group is arranged so that the end portions thereof do not face each other. The rice cooker according to any one of claims 1 to 4, wherein the number of turns of the outside bottom heating coil is smaller than the number of turns of the inside heating coil. The rice cooker according to any one of claims 1 to 5, wherein the low-frequency inductance value of the outside bottom heating coil and the low-frequency inductance value of the inside heating coil are substantially the same.