JP2011103248A - Magnetic shielding device, and electromagnetic induction heating cooker equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic shielding device capable of responding to various shapes of protection object regions, and to provide an electromagnetic induction heating cooker equipped with the same. <P>SOLUTION: The magnetic shielding device S, which protects a plurality of electric components installed inside an electromagnetic induction heating cooker 1 from magnetic flux composed of a magnetic field generated by a heating coil 4, is equipped with one or more metal plates 19 which are respectively interposed between one or more first protection regions 25 out of a plurality of protection object regions, in which the electric components as protection objects are installed, and the heating coil 4, and one or more metal wires 20 which enclose a part or whole of the surrounding of other one or more second protection object regions 26 out of the plurality of protection object regions, and are arranged so as to interlink with the magnetic flux composed of the magnetic field. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic shield for protecting a plurality of electrical components provided in an electromagnetic induction heating cooker from a magnetic field generated by a heating coil, and electromagnetic induction heating cooking provided with the magnetic shield Related to the vessel.

  An electromagnetic induction heating type cooking device includes a heating coil that generates eddy current in a heating element (such as a pan) by electromagnetic induction, and a metal heating element (pan) that generates Joule heat when the eddy current flows. Prepare. In such an electromagnetic induction heating cooker, the magnetic field generated by the heating coil does not act only on the heating element to flow eddy current, but also acts on other conductive parts to generate eddy current. There is a possibility of flowing. For example, when a part of the casing that forms the outer shape of the electromagnetic induction heating cooker is formed of a metal material in order to give the appearance a clean feeling, the magnetic field generated by the heating coil is generated by the electromagnetic induction heating cooker. If it leaks into the case, there is a possibility that eddy currents are generated in the metal material portion and the case becomes hot.

  On the other hand, Patent Document 1 discloses a magnetic shielding device installed inside an electromagnetic induction heating cooker, particularly for preventing leakage of a magnetic field to a lower housing and a side housing of the electromagnetic induction heating cooker. A magnetic-shielding device is disclosed. Specifically, the magnetic-shielding device described in Patent Document 1 includes a ferrite core and a metal plate provided below the heating coil in order to prevent leakage of a magnetic field to the lower housing of the electromagnetic induction heating cooker, In order to prevent leakage of the magnetic field to the side housing of the electromagnetic induction heating cooker, a metal wire such as a covered electric wire provided on the side of the heating element is provided. Thus, the magnetic-shield apparatus provided in the conventional electromagnetic induction heating type cooking appliance is for preventing the leakage of the magnetic field to the lower housing | casing and side housing | casing of an electromagnetic induction heating cooking device.

Japanese Patent Laying-Open No. 2005-28020

  Rather than preventing leakage of the magnetic field to the lower housing and side housing of the electromagnetic induction heating cooker, a plurality of electrical components provided inside the electromagnetic induction heating cooker are generated by the heating coil. There is also a need to protect against magnetic fields. In response to such a requirement, a magnetic-shielding device for magnetic-shielding a specific electric circuit board housed in a part susceptible to the magnetic field generated by the heating coil inside the electromagnetic induction heating cooker Can also be assumed. For example, a magnetic-shielding device having a metal plate that is the same size as a specific electric circuit board and is interposed between the electric circuit board and the heating coil can be assumed. In this case, the electric circuit board is regarded as a protection target area where an electrical component to be protected is provided.

  However, the size of the electric circuit board (that is, the size of the protection target area to be protected by the magnetic shielding device) is changed accordingly when the size or number of electric components to be mounted is changed. In that case, in order to effectively shield the specific electric circuit board, the size of the magnetic shielding metal plate must be changed each time. Therefore, when trying to change the size or number of electrical components to be installed according to the type of electromagnetic induction heating cooker or when changing the model of an electromagnetic induction heating cooker, etc. Not only the effort and cost required to change the shape of the substrate, but also the effort and cost to change the shape of the magnetic shielding metal plate according to the shape change of the protection target area (for example, for processing the metal plate) New mold manufacturing costs, etc.) are also required. Such effort and cost should be reduced as much as possible.

  This invention is made | formed in view of said subject, The objective is to provide the magnetic-shielding apparatus which can respond to the protection object area | region of various shapes, and the electromagnetic induction heating type cooking appliance provided with the same.

In order to achieve the above object, the magnetic shield device according to the present invention is characterized by a magnetic shield device for protecting a plurality of electrical components provided in an electromagnetic induction heating cooker from a magnetic field generated by a heating coil. Because
One or more metal plates respectively interposed between one or more first protection target regions and a heating coil among a plurality of protection target regions provided with electrical components to be protected; and One or more metal wires that surround part or all of the periphery of one or more second protection target regions of the plurality of protection target regions and are respectively arranged so as to interlink with the magnetic flux generated by the magnetic field. In the point.

According to the above characteristic configuration, the protection target region can be protected from the magnetic field generated by the heating coil with the metal plate and the metal wire. Specifically, the first protection target area of the protection target area is effectively protected by the metal plate. In addition, the interlinkage magnetic flux is canceled out and weakened on the metal wires arranged in part or all of the periphery of the second protection target area so as to interlink with the magnetic flux generated by the magnetic field generated by the heating coil. An electromotive force (back electromotive force) that generates a magnetic field is generated. Therefore, the second protection target area surrounded by the metal wire is effectively protected by the metal wire from the magnetic field generated by the heating coil. That is, when there is a protection target region having a fixed shape, the protection target region (that is, the first protection target region) can be effectively protected by the metal plate formed in the fixed shape. In addition, even if a protection target area having a shape that cannot be effectively protected by a metal plate having a predetermined shape occurs, the shape of the metal wire is changed to surround part or all of the periphery of the second protection target area. Therefore, the protection target area (that is, the second protection target area) can be effectively protected with the metal wire.
Therefore, it is possible to provide a magnetic shield device that can deal with various shapes of protection target areas.

  Another characteristic configuration of the magnetic shielding device according to the present invention is to divide a substrate on which some of the electrical components to be protected are mounted into the first protection target region and the second protection target region, It is in the point which protects from the said magnetic field.

The shape of the substrate on which some of the electrical components to be protected are mounted can vary depending on the type, number, size, etc. of the mounted electrical components.
According to this characteristic configuration, even when the board on which some of the electrical components to be protected cannot be effectively protected only by the metal plate, the region that cannot be effectively protected by the metal plate (that is, the first 2 protection target area) can be effectively protected using a metal wire surrounding a part or all of the periphery of the second protection target area. That is, the entire substrate can be effectively protected from the magnetic field by the combination of the metal plate and the metal wire.

  Still another characteristic configuration of the magnetic shielding device according to the present invention is that the metal wire is disposed around the first protection target region and the second protection target region.

  According to the above characteristic configuration, the metal wire surrounds not only the second protection target region but also the first protection target region. That is, the magnetic flux interlinking the metal wires (that is, the magnetic flux acting on the first protection target region and the second protection target region) is weakened by the magnetic field generated by the metal wire in which the counter electromotive force is generated. As a result, the metal plate and the metal wire can double protect the first protection target area from the magnetic field generated by the heating coil.

  Still another characteristic configuration of the magnetic-shielding device according to the present invention is that the metal wire and the metal plate are electrically connected.

  According to the above characteristic configuration, since the metal wire and the metal plate are electrically connected, the metal plate is formed by the metal wire and is a portion of the portion surrounding the second protection target region that surrounds the whole or a part thereof. Part of it. That is, the metal plate acts as a part of the metal wire and can contribute to the protection of the second protection target region.

In order to achieve the above object, the characteristic configuration of the electromagnetic induction heating cooker according to the present invention is as follows:
The magnetic shielding device,
A metal heating element,
The heating coil for generating an eddy current in the heating element by electromagnetic induction;
A rectifier circuit that rectifies an alternating current supplied from an alternating current power supply;
An inverter circuit section that converts the current rectified by the rectifier circuit section into a predetermined high-frequency current and supplies it to the heating coil;
Provided in the middle of the electric circuit between the AC power supply and the rectifier circuit unit, and a filter circuit unit for removing noise in a predetermined frequency range,
The metal plate is located between the filter circuit portion serving as the first protection target region and the heating coil.

  According to the above characteristic configuration, since the filter circuit unit is effectively protected by the metal plate, it is possible to prevent new noise from being superimposed on the filter circuit unit. As a result, it is possible to provide an electromagnetic induction heating type cooking device in which noise in a predetermined frequency range is not output to the AC power source.

It is a longitudinal cross-sectional view of a rice cooker. It is a block diagram which shows the structure of a rice cooker. It is a longitudinal cross-sectional view about a part of rice cooker. It is a top view of a magnetic-shielding apparatus. It is a block diagram which shows another structure of a rice cooker. It is a block diagram which shows another structure of a rice cooker. It is a block diagram which shows another structure of a rice cooker. It is another top view of a magnetic-shielding apparatus.

<First Embodiment>
Hereinafter, a magnetic shield device according to a first embodiment and an electromagnetic induction heating cooker including the same will be described with reference to the drawings. In this embodiment, a rice cooker is illustrated as an electromagnetic induction heating type cooking device.
FIG. 1 is a longitudinal sectional view of a rice cooker. FIG. 2 is a block diagram showing the configuration of the rice cooker. FIG. 3 is a longitudinal sectional view of a part of the rice cooker. FIG. 4 is a plan view of the magnetic shield device.
The rice cooker 1 has a metal heating element (pan) 3 that generates heat. Inside the rice cooker 1, a protective material 2 for housing the heating element 3 is provided. The protective material 2 is formed of a nonconductive material. Outside the protective material 2 is provided a heating coil 4 that generates eddy currents in the heating element 3 by electromagnetic induction. Specifically, the heating coil 4 includes a bottom portion of the heating element 3, specifically, a protective material 2 and a ferrite core 5 installed for the purpose of preventing leakage of a magnetic field to the outside of the rice cooker 1. It is provided in between. When a high frequency current is passed through the heating coil 4, an eddy current is generated in the heating element 3 by the magnetic field generated by the heating coil 4, and the heating element 3 generates heat due to Joule heat generated by the flow of the eddy current. To do. Further, outside the protective material 2, main controls including a filter circuit unit 10, a rectifier circuit unit 12, an inverter circuit unit 13, an inverter drive circuit unit 14, and a microcomputer unit 15 as electrical components constituting the rice cooker 1. A circuit unit 7, a current transformer unit 17, a stabilized power circuit unit 16, an operation display circuit unit 8, a fan 6, a temperature sensor 11, and the like are provided. In the present embodiment, the filter circuit unit 10 and the current transformer unit 17 are mounted on the filter circuit board 18. The rectifier circuit unit 12, the inverter circuit unit 13, the inverter drive circuit unit 14, and the stabilized power circuit unit 16 are mounted on the IH substrate 22. The main control circuit unit 7 including the microcomputer unit 15 is mounted on the main control circuit board 21. The operation display circuit unit 8 is mounted on the operation display circuit board 9.

  The filter circuit unit 10 is provided in the middle of an electric circuit between an AC power source (for example, commercial power source) 23 and a rectifier circuit unit 12 that rectifies an AC current supplied from the AC power source 23, for example, an inverter circuit. Noise in a predetermined frequency range generated in the unit 13 or the like is removed. In the present embodiment, as illustrated in FIG. 4, the filter circuit unit 10 includes a circuit having a coil 10 a and a capacitor 10 b. The rectifier circuit unit 12 is configured by, for example, a diode bridge circuit. By providing the filter circuit unit 10 in the rice cooker 1, it is possible to suppress high-frequency noise in a predetermined frequency range generated in the electric circuit inside the rice cooker 1 from going toward the AC power source 23.

  The inverter circuit unit 13 converts the current rectified by the rectifier circuit unit 12 into a predetermined high-frequency current and supplies it to the heating coil 4. The inverter circuit unit 13 has a switching element such as an IGBT as a high-frequency switching element. The inverter drive circuit unit 14 performs on / off control of energization to the heating coil 4 by performing on / off control of the switching element included in the inverter circuit unit 13. The microcomputer unit 15 is connected to the input side of the inverter drive circuit unit 14, and the inverter circuit unit 13 is connected to the output side of the inverter drive circuit unit 14. The operation of the inverter drive circuit unit 14 is controlled by the microcomputer unit 15.

The current transformer unit 17 detects an input current from the AC power supply 23. The detection result of the current transformer unit 17 is transmitted to the microcomputer unit 15.
The stabilized power supply circuit unit 16 generates a predetermined stabilized power supply from the AC power supply 23. In the present embodiment, the stabilized power supply circuit unit 16 includes a voltage (for example, 20V) for operating the inverter drive circuit unit 14 and the fan 6, and a voltage (for example, operating the microcomputer unit 15 and the temperature sensor 11). For example, 5V) is generated. The fan 6 is provided to cool the inside of the rice cooker 1 and its operation is controlled by the microcomputer unit 15. A temperature sensor 11 including a detection unit 11 a and a circuit unit 11 b is provided to detect the temperature of the heating element 3, and the detection result is transmitted to the microcomputer unit 15.

As described above, the heating coil 4 is provided inside the rice cooker 1, and a plurality of electric components as described above are also provided. In addition, when these electric components are placed under the influence of a magnetic field generated by the heating coil 4, noise may be generated in the electric circuit inside the rice cooker 1.
So, in this embodiment, the magnetic-shielding apparatus S with which the rice cooker 1 is provided is one or more 1st 1st protection object area | regions 25 among the some protection object area | regions in which the electrical component made into a protection object is provided so that it may mention later. And one or more metal plates 19 respectively interposed between the heating coil 4 and the second protection target area around one or more second protection target areas 26 of the plurality of protection target areas. One or more metal wires 20 are provided so as to surround a part or all of the periphery of the region 26 and to be interlinked with the magnetic flux generated by the magnetic field generated by the heating coil.

Below, the structure of the magnetic-shielding apparatus S of this embodiment is demonstrated.
As shown in FIGS. 1 to 4, the filter circuit board 18 is mounted on the filter circuit board 18. The filter circuit board 18 is originally for mounting electrical components (coil 10a, capacitor 10b, etc.) constituting the filter circuit unit 10. Therefore, a metal plate 19 for protecting the filter circuit unit 10 from the magnetic field generated by the heating coil 4 is interposed between the filter circuit unit 10 and the heating coil 4. The predetermined shape of the metal plate 19 is a shape and size that can effectively protect at least the electrical components constituting the filter circuit unit 10 from the magnetic field generated by the heating coil 4.

  In the present embodiment, a current transformer unit 17 is also mounted on the filter circuit board 18. Since the coil 10a, the capacitor 10b, and the like constituting the filter circuit unit 10 and the current transformer unit 17 are relatively large components, it is possible to increase the storage efficiency in the rice cooker 1 by combining them on one substrate. . The filter circuit board 18 of the present embodiment that needs to mount both the filter circuit unit 10 and the current transformer unit 17 is larger than the conventional filter circuit board that only needs to mount the filter circuit unit 10. Therefore, the size of a predetermined metal plate 19 prepared in advance to protect the entire filter circuit board that only needs to be mounted with the filter circuit unit 10 is mounted with both the filter circuit unit 10 and the current transformer unit 17. It becomes smaller than the required filter circuit board 18 of this embodiment. That is, when the metal plate 19 manufactured to protect the entire filter circuit board that only needs to be mounted with the filter circuit unit 10 is used in the filter circuit board 18 of the present embodiment, the filter does not change in size from the conventional one. Although the area of the circuit unit 10 can be effectively protected by the metal plate 19, the area of the newly provided current transformer unit 17 cannot be effectively protected by the metal plate 19.

  By the way, the magnetic-shielding apparatus S of this embodiment is interposed between one or more 1st protection object area | regions 25 and the heating coil 4 of the some protection object area | region in which the electrical component made into protection object is provided. Surrounding all of the periphery of the second protection target region 26 and surrounding one of the one or more metal plates 19 to be mounted and one or more second protection target regions 26 of the plurality of protection target regions, and for heating One or more metal wires 20 are provided so as to be interlinked with the magnetic flux generated by the magnetic field generated by the coil 4. That is, in the filter circuit board 18 illustrated in FIGS. 3 and 4, the area where the filter circuit unit 10 is provided on the filter circuit board 18 is regarded as the first protection target area 25, and on the filter circuit board 18. The region where the current transformer unit 17 is provided can be regarded as the second protection target region 26.

  A metal plate 19 is interposed between the filter circuit unit 10 and the heating coil 4 so as to surround the entire periphery of the current transformer unit 17 and to interlink with the magnetic flux generated by the magnetic field generated by the heating coil 4. A metal wire 20 is arranged. That is, an electromotive force (back electromotive force) is generated in the metal wire 20 arranged so as to be linked to the magnetic flux generated by the magnetic field generated by the heating coil 4 so as to cancel and weaken the linked magnetic flux. Power). Therefore, the current transformer portion 17 (second protection target region 26) surrounded by the metal wire 20 is effectively protected by the metal wire 20 from the magnetic flux generated by the magnetic field generated by the heating coil 4. In this embodiment, although the metal wire 20 is arrange | positioned on the same surface as the metal plate 19, the metal plate 19 and the metal wire 20 do not need to be on the same surface. Moreover, in this embodiment, although the winding number of the metal wire 20 is about 2 times, the winding number can be changed suitably.

  That is, as illustrated in FIG. 3, the magnetic flux indicated by the broken line acting on the filter circuit unit 10 as the first protection target region 25 can be effectively shielded by the metal plate 19, and the current transformer unit as the second protection target region 26. The magnetic flux indicated by the alternate long and short dash line acting on 17 is weakened by the metal wire 20. Thus, in the magnetic-shielding device S of this embodiment, since the arrangement state of the metal wire 20 can be easily changed so as to surround the entire periphery of the second protection target region 26, the metal plate 19 is effective. Even if a protection target region having a shape that cannot be protected is generated, the protection target region (that is, the second protection target region 26) can be effectively protected by the metal wire 20. In particular, since the shape of the metal wire 20 can be freely deformed, even if the metal wire 20 can be installed in an appropriate space inside the rice cooker 1 while being bent, and the protection target area has various shapes. There is an advantage that the metal wire 20 can be installed after being appropriately deformed according to its shape.

  Furthermore, in this embodiment, the metal wire 20 surrounds not only the current transformer unit 17 (second protection target region 26) but also the filter circuit unit 10 (first protection target region 25). That is, the magnetic flux interlinking the metal wire 20 (all magnetic fluxes indicated by the broken line and the alternate long and short dash line in FIG. 3) is weakened by the magnetic field generated by the metal wire 20 in which the counter electromotive force is generated. As a result, the filter circuit unit 10 is double protected by the metal plate 19 and the metal wire 20. Furthermore, the metal wire 20 is electrically connected to the metal plate 19 by a crimp terminal 24 or the like. In particular, both ends of the metal wire 20 are electrically connected to different portions of the metal plate 19. As a result, the metal plate 19 constitutes a part of a portion that is formed by the metal wire 20 and surrounds the entire periphery of the second protection target region 26. That is, the metal plate 19 acts as a part of the metal wire 20 and can contribute to protection of the current transformer unit 17.

Second Embodiment
FIG. 5 is a block diagram illustrating a configuration of the rice cooker according to the second embodiment. The rice cooker of 2nd Embodiment is the same as that of the rice cooker of 1st Embodiment except the filter circuit part, the current transformer part, and the stabilization power supply circuit part being mounted in the filter circuit board. Although the structure of the rice cooker of 2nd Embodiment is demonstrated below, description is abbreviate | omitted about the structure similar to 1st Embodiment.

As shown in FIG. 5, in the present embodiment, the filter circuit board 18 includes a current transformer unit 17 and a stabilized power circuit unit 16 in addition to the filter circuit unit 10. Since the electrolytic capacitor (not shown) constituting the stabilized power supply circuit unit 16 is a relatively large component, the storage efficiency in the rice cooker 1 can be increased by collecting them on one substrate.
In the present embodiment, similarly to the example described in the first embodiment, the region on the filter circuit board 18 where the filter circuit unit 10 is provided is regarded as the first protection target region 25, and the current on the filter circuit substrate 18 is The region where the transformer unit 17 is provided can be regarded as the second protection target region 26, and the region where the stabilized power circuit unit 16 on the filter circuit board 18 is provided can be regarded as the second protection target region 26. Although not shown in the present embodiment, a metal plate 19 is interposed between the filter circuit unit 10 and the heating coil 4 as in the first embodiment.

  Further, a metal wire 20 is disposed so as to surround a part or all of the periphery of the current transformer unit 17 and to interlink with the magnetic flux generated by the magnetic field generated by the heating coil 4, and around the stabilized power circuit unit 16. The metal wire 20 is disposed so as to surround a part or all of the wire and to interlink with the magnetic flux generated by the magnetic field generated by the heating coil 4. In this case, the metal line 20 arranged around the current transformer unit 17 and the metal line 20 arranged around the stabilized power supply circuit unit 16 may be configured by the same metal line 20, or A separate metal wire 20 may be used. Further, when the metal wires 20 arranged around the current transformer unit 17 and the metal wires 20 arranged around the stabilized power supply circuit unit 16 are constituted by separate metal wires 20, the windings of the metal wires 20 are wound. The number can be appropriately set according to the magnitude of the shielding effect of the magnetic field required for each. For example, the metal wire 20 disposed around the current transformer unit 17 is configured by approximately two turns as illustrated in FIG. 4, and the metal wire 20 disposed around the stabilized power circuit unit 16 is approximately 3 turns. You may comprise by winding etc. As the number of turns increases, the counter electromotive force generated in the metal wire 20 increases, so that the magnetic field for canceling the interlinkage magnetic flux increases.

<Third Embodiment>
FIG. 6 is a block diagram showing the configuration of the rice cooker of the third embodiment. The rice cooker of 3rd Embodiment is 1st except that the microcomputer part and the circuit part of a temperature sensor are mounted in the main control circuit board 21, and in addition, the magnetic-shield apparatus is provided in the main control circuit board 21. It is the same as that of the rice cooker of embodiment. Although the structure of the rice cooker of 3rd Embodiment is demonstrated below, description is abbreviate | omitted about the structure similar to 1st Embodiment.

  As shown in FIG. 6, in the present embodiment, a circuit unit 11 b of the temperature sensor 11 is mounted on the main control circuit board 21 in addition to the microcomputer unit 15. For the purpose of downsizing the rice cooker 1 or the like, the main control circuit board 21 accommodated in the rice cooker 1 may be disposed close to the heating coil 4. In this case, it is necessary to protect the main control circuit board 21 and the like from the magnetic field generated by the heating coil 4. In the present embodiment, the area where the microcomputer unit 15 is provided on the main control circuit board 21 is regarded as the first protection target area 25, and the circuit part 11 b of the temperature sensor 11 on the main control circuit board 21 is provided. The area to be protected is regarded as the second protection target area 26. Although not illustrated in the present embodiment, a metal plate 19 is interposed between the microcomputer unit 15 and the heating coil 4 as illustrated in FIGS. 3 and 4 and the like. Further, the metal wire 20 is disposed so as to surround a part or all of the periphery of the circuit unit 11 b of the temperature sensor 11 and to interlink with the magnetic flux generated by the magnetic field generated by the heating coil 4. As a result, since the magnetic flux interlinking the metal wire 20 is weakened by the magnetic field generated by the metal wire 20 in which the counter electromotive force is generated, the circuit portion 11b of the temperature sensor 11 can be effectively protected by the metal wire 20. In particular, the arrangement location of the circuit unit 11b of the temperature sensor 11 may be changed as necessary. In such a case, it is difficult to predict the influence of the magnetic field generated in the heating coil 4 in advance. Therefore, the metal wire 20 is advantageous in that the shape can be easily changed or added in order to effectively protect the circuit portion 11b of the temperature sensor 11.

  In the example shown in FIG. 6, a metal plate 19 is installed to protect the filter circuit unit 10, and a metal wire 20 is installed to protect the current transformer unit 17. That is, the magnetic shield device S protects each of the filter circuit unit 10 and the microcomputer unit 15 with the separate metal plate 19 as the first protection target region 25, and the current transformer unit 17 and the circuit unit 11 b of the temperature sensor 11 are protected. Each is protected by a separate metal wire 20 as a second protection target region 26.

<Fourth embodiment>
FIG. 7 is a block diagram showing the configuration of the rice cooker of the fourth embodiment. The rice cooker of the fourth embodiment is different from the first embodiment in that a magnetic shielding device is provided for protecting an electrical component provided on an electrical circuit between the filter circuit unit and the AC power supply. ing. Although the structure of the rice cooker of 4th Embodiment is demonstrated below, description is abbreviate | omitted about the structure similar to 1st Embodiment.

  As shown in FIG. 7, in the present embodiment, a current fuse 27 and a varistor 28 as electrical components are provided on the electrical circuit between the filter circuit unit 10 and the AC power supply 23. The varistor 28 is an element whose electric resistance value varies greatly according to the applied voltage. For example, when a normal low voltage is applied to the varistor 28, the electric resistance value of the varistor 28 is large, so that no current flows through the varistor 28. On the other hand, when a large voltage is applied to the varistor 28, the electric resistance value of the varistor 28 is significantly reduced and a large current flows through the varistor 28. As a result, in the present embodiment, since a large current flows through the current fuse 27, the electric circuit is cut by the current fuse 27, and the downstream filter circuit unit 10 and the like are protected. The current fuse 27 and the varistor 28 are mounted on the filter circuit board 18 together with the filter circuit unit 10. In the present embodiment, the current transformer 17 is not mounted on the filter circuit board 18.

  Also in this embodiment, the region where the filter circuit unit 10 is provided on the filter circuit board 18 is regarded as the first protection target region 25. A metal plate 19 is interposed between the filter circuit unit 10 and the heating coil 4. In addition, the region where the current fuse 27 and the varistor 28 are provided on the filter circuit board 18 is regarded as the second protection target region 26. The metal wire 20 is disposed so as to surround a part or all of the periphery of the current fuse 27 and the varistor 28 and to interlink with the magnetic flux generated by the magnetic field generated by the heating coil 4. Therefore, the filter circuit unit 10 as the first protection target region 25 and the current fuse 27 and the varistor 28 as the second protection target region 26 are heated by the magnetic shield device S including the metal plate 19 and the metal wire 20. It is effectively protected from the magnetic flux generated by the magnetic field generated by the coil 4.

<Another embodiment>
<1>
In the said embodiment, the shape of the metal plate 19 and the metal wire 20 with which the magnetic-shielding apparatus S is provided can be changed suitably. For example, as shown in FIG. 8 as a modified example of FIG. 4, the filter circuit board 18 includes a first protection target region 25 in which the filter circuit unit 10 is provided and a second protection target region 26 in which the current transformer unit 17 is provided. The metal plate 19 is installed to protect the filter circuit section 10 as the first protection target area 25, and the metal wire 20 is installed only around the current transformer section 17 as the second protection target area 26. May be. Further, in FIG. 4, the metal wire 20 is shaped so as to surround the entire periphery of the current transformer portion 17 as the second protection target region 26, but as shown in FIG. 8, the metal wire 20 is formed in the second protection target region. The shape may surround a part of the periphery of the current transformer portion 17 as 26.

<2>
In the above-described embodiment, the shape of the metal wire 20 is not limited to the curved arcuate shape and the annularly bent shape as illustrated in FIGS. 4 and 8, and is a shape that is partially bent at an angle. It may be.
Further, the metal wire 20 may not be electrically connected to the metal plate 19. For example, only the metal wire 20 may be provided independently, or the metal wire 20 may be provided in a state of being connected to the ground or the like. Furthermore, only one end of the metal wire 20 may be electrically connected to the metal plate 19.

<3>
In the said embodiment, although the example of the magnetic-shielding apparatus S for protecting the electrical component mounted in several board | substrates from the magnetic field generate | occur | produced with the coil 4 for a heating was shown, it may protect other electrical components which are not mentioned above. A simple magnetic shield device S may be configured. Moreover, the installation positions of the plurality of electrical components described in the above embodiment can be changed as appropriate.
Furthermore, although the rice cooker 1 was illustrated as an electromagnetic induction heating type cooking device, you may provide the magnetic-shielding apparatus S with respect to another various electromagnetic induction heating type cooking device.

  The present invention relates to a magnetic shield for protecting a plurality of electrical components provided in an electromagnetic induction heating cooker from a magnetic field generated by a heating coil, and electromagnetic induction heating cooking provided with the magnetic shield It can be used for the vessel.

1 Rice cooker (electromagnetic induction heating cooker)
4 Heating coil 10 Filter circuit unit 11 Temperature sensor 11a Sensor unit 11b Circuit unit 12 Rectifier circuit unit 13 Inverter circuit unit 15 Microcomputer unit 16 Stabilized power supply circuit unit 17 Current transformer unit 18 Filter circuit board 19 Metal plate 20 Metal wire 21 Main control circuit board 23 AC power supply 25 First protection target area 26 Second protection target area S Magnetic shield

Claims (5)

A magnetic shielding device for protecting a plurality of electrical components provided inside an electromagnetic induction heating cooker from a magnetic field generated by a heating coil,
One or more metal plates respectively interposed between one or more first protection target regions and a heating coil among a plurality of protection target regions provided with electrical components to be protected; and One or more metal wires that surround part or all of the periphery of one or more second protection target regions of the plurality of protection target regions and are respectively arranged so as to interlink with the magnetic flux generated by the magnetic field. Magnetic shield.   The magnetic-shielding device of Claim 1 which divides the board | substrate with which some of the electrical components made into the said protection object are mounted into the said 1st protection object area | region and the said 2nd protection object area | region, and protects from the said magnetic flux.   The magnetic-shielding device according to claim 1 or 2, wherein the metal wire is disposed around the first protection target area and the second protection target area.   The magnetic shielding device according to any one of claims 1 to 3, wherein the metal wire and the metal plate are electrically connected. The magnetic-shield device as described in any one of Claims 1-4,
A metal heating element,
The heating coil for generating an eddy current in the heating element by electromagnetic induction;
A rectifier circuit that rectifies an alternating current supplied from an alternating current power supply;
An inverter circuit section that converts the current rectified by the rectifier circuit section into a predetermined high-frequency current and supplies it to the heating coil;
Provided in the middle of the electric circuit between the AC power supply and the rectifier circuit unit, and a filter circuit unit for removing noise in a predetermined frequency range,
The said metal plate is an electromagnetic induction heating type cooking appliance interposed between the said filter circuit part as said 1st protection object area | region, and the said heating coil.

Images