JP2021026819A - Induction heater - Google Patents

Abstract

To provide an induction heater capable of performing efficient air discharge (heat discharge) while performing sufficient magnetic shielding against a magnetic field generated from an induction heating coil.SOLUTION: An induction heater 100 comprises: a body 130 to be heated; a first induction heating coil 113a disposed so as to face the body to be heated; a second induction heating coil 113b disposed outside the first induction heating coil so as to face the body to be heated and be separated from the first induction heating coil; a first magnetic shielding part FC1 disposed on the opposite side of the first induction heating coil to the side of the body to be heated; and a second magnetic shielding part FC2 disposed on the opposite side of the second induction heating coil to the side of the body to be heated. The induction heater further comprises a third magnetic shielding part SP1, at least part of which is disposed between the outer periphery of the first induction heating coil and the outer periphery of the second induction heating coil in a plan perspective view.SELECTED DRAWING: Figure 6

Description

The present invention relates to an induction heater.

A rice cooker body whose upper surface has been opened in the past, an inner pot that is detachably stored in the rice cooker body, a protective frame that stores the inner pot in the rice cooker body, and a protective frame installed at the bottom of the protective frame. A high-frequency power is supplied to the first heating coil along the bottom surface of the inner pot, the second heating coil along the lower side surface of the inner pot, and the first and second heating coils to guide the inner pot. An inverter to be heated, a control means for controlling the inverter to control induction heating such as during rice cooking or heat retention, and prevention of leakage magnetic fields from the first and second heating coils during induction heating. A non-magnetic metal plate is provided, and the non-magnetic metal plate is installed on the bottom surface of the rice cooker body so as to face the first and second heating coils, and the end surface is the second heating coil. A rice cooker having a bent portion over the entire circumference and formed in a ring shape has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2010-240051).

Japanese Unexamined Patent Publication No. 2010-240051

By the way, usually, in an induction heater such as an induction heating type rice cooker, a magnetic shield member (for example, in Patent Document 1) is provided around the outside of the induction heating coil in order to prevent the magnetic field generated from the induction heating coil from leaking to the outside. Non-magnetic metal plate) is installed. Such a magnetic shield member generally has a bottomed cylindrical shape to cover the entire induction heating coil from below, and is installed above the bottom wall portion of the induction heater main body. However, in such a case, even if an exhaust port is formed on the bottom wall of the induction heater main body, there arises a problem that exhaust (exhaust heat) cannot be performed efficiently.

An object of the present invention is to provide an induction heater capable of efficiently exhausting (exhausting heat) while sufficiently shielding the magnetic field generated from the induction heating coil.

The induction heater according to the present invention
With the heated body,
A first induction heating coil arranged so as to face the heated body,
A second induction heating coil which is arranged outside the first induction heating coil so as to face the heated body and to be separated from the first induction heating coil.
The first magnetic shield portion arranged on the opposite side of the first induction heating coil on the side to be heated,
A second magnetic shield disposed on the opposite side of the second induction heating coil on the side to be heated,
With
Further, a third magnetic shield portion is further provided, at least a part of which is arranged between the outer circumference of the first induction heating coil and the outer circumference of the second induction heating coil in plan perspective.

According to the above configuration, the first magnetic shield is arranged on the opposite side of the first induction heating coil on the heated body side, and the second magnetic shield is arranged on the opposite side of the second induction heating coil on the heated body side. In a plan view, at least a part of the third magnetic shield is arranged between the outer circumference of the first induction heating coil and the outer circumference of the second induction heating coil. Then, in this induction heater, the first magnetic shield portion suppresses the magnetic field generated from the first induction heating coil from leaking to the outside, and the second magnetic field generated from the second induction heating coil leaks to the outside. The magnetically shielded portion suppresses, and further, the third magnetically shielded portion suppresses the magnetic field leaking between the first magnetically shielded portion and the second magnetically shielded portion from leaking to the outside. Therefore, in this induction heater, it is possible to sufficiently shield the magnetic field generated from the induction heating coil, and secure an exhaust space between the first magnetic shield portion, the second magnetic shield portion and the third magnetic shield portion. can do. Therefore, in this induction heater, it is possible to efficiently exhaust the magnetic field while sufficiently shielding the magnetic field generated from the induction heating coil.

Further, in this induction heater, the distance between the first magnetic shield portion and the second magnetic shield portion can be set relatively freely by providing the third magnetic shield portion, and the first induction heating coil and the first induction heating coil and the second magnetic shield portion can be set relatively freely. The distance from the second induction heating coil can be set relatively freely. Therefore, in this induction heater, the heating efficiency can be adjusted.

In the present invention
It is preferable that the third magnetic shield portion has an annular shape.

As a result of diligent studies by the inventor of the present application, it has been clarified that when the third magnetic shield member is made annular, the magnetic shielding effect is improved as compared with the case where the third magnetic shield member is made non-cyclic. Therefore, in this induction heater, it is possible to further suppress the leakage of the magnetic field generated from the induction coil to the outside.

In the present invention
A bottom wall portion on which an exhaust port is formed, which is arranged under the heated body, and
A fourth magnetically shielded portion disposed below the first magnetically shielded portion is further provided.
It is preferable that at least a part of the exhaust port is formed between the third magnetic shield portion and the fourth magnetic shield portion in plan perspective.

According to the above configuration, the exhaust space between the third magnetic shield portion and the fourth magnetic shield portion can be communicated with the exhaust port in a short distance, and flows between the third magnetic shield portion and the fourth magnetic shield portion. Exhaust can be efficiently guided to the exhaust port.

It is a front view of the rice cooker which concerns on embodiment of this invention. It is a top view of the rice cooker which concerns on embodiment of this invention. 1A and 2B are sectional views taken along the line II. FIG. 2 is a partial cross-sectional view of II-II of FIG. 2 (the main body of the rice cooker according to the embodiment of the present invention is cut along the ferrite core arrangement direction, and some members such as shoulder members are drawn. It is omitted.). FIG. 2 is a partial cross-sectional view taken along the line III-III of FIG. 2 (drawing of some members such as shoulder members is omitted). It is a bottom view of the state which the bottom wall was removed from the rice cooker which concerns on embodiment of this invention. It is a top view which shows the bottom wall, the horizontal shielding plate and the bottom shielding plate which constitute the rice cooker which concerns on embodiment of this invention. It is a magnetic field strength measurement result in the vertical direction of the rice cooker according to the embodiment of the present invention in the case where the horizontal shielding plate is not arranged. It is a magnetic field strength measurement result in the vertical direction of the rice cooker according to the embodiment of the present invention in the case where the horizontal shielding plate is arranged.

<Structure of Rice Cooker According to Embodiment of the Present Invention>
The rice cooker 100 according to the embodiment of the present invention is an induction heating type pressure rice cooker, and as shown in FIGS. 1 to 3, mainly the main body 110, the inner pot 130, the lid 140 and the hinge. It is composed of a mechanism 150. Hereinafter, these components will be described in detail.

1. 1. Main body As shown in FIGS. 1 to 3, the main body 110 mainly includes a housing 111, a handle 112, a heat insulating material (not shown), an induction heating coil 113, a ferrite core assembly 121, a thermistor 114, and a blower fan. It is composed of 115, a heat sink 116, an operation panel 117, a power supply circuit board 118, a control circuit board 119, and an automatic winding type power cord unit 120. Hereinafter, these components will be described in detail.

(1) Housing As shown in FIGS. 1, 3 and 6, the housing 111 is mainly composed of a side wall 111a, a bottom wall 111b, a shoulder member 111c and a protective frame 111d, and is a heat insulating material ( (Not shown), induction heating coil 113, ferrite core assembly 121, horizontal shielding plate SP1, bottom shielding plate SP2, thermistor 114, blower fan 115, heat sink 116, power supply circuit board 118, control circuit board 119 and automatic winding type. It houses the power cord unit 120 and the like. Further, an operation panel 117 is arranged on the upper side of the front side of the shoulder member 111c. Hereinafter, each component of the housing 111 will be described in detail.

The side wall 111a is an enclosure wall that exhibits a substantially rectangular shape in a plan view as shown in FIG. 6, and covers the side surface of the main body 110 as shown in FIGS. 1 and 3.

The bottom wall 111b is a substantially rectangular plate-like body, which is fitted under the side wall 111a as shown in FIGS. 1 and 3 to 5 and covers the opening under the side wall 111a. As shown in FIG. 7, the bottom wall 111b is mainly formed with a cover member accommodating portion 127a, an intake port Os, and an exhaust port Oe. The cover member accommodating portion 127a is a portion for accommodating the cover member 127 (described later) that supports the thermistor 114 (described later), and is formed in the central portion of the bottom wall 111b as shown in FIG. .. The intake port Os is a portion for sucking the air outside the housing 111 into the inside, and is formed in the front portion of the bottom wall 111b as shown in FIGS. 3 and 7. The exhaust port Oe is a portion for exhausting the air inside the housing 111 to the outside, and is formed on the rear portion and the left and right side portions of the bottom wall 111b as shown in FIG. 7. Here, as shown in FIG. 7, a part of the exhaust port Oe formed in the rear portion of the bottom wall 111b is between the horizontal shielding plate SP1 (described later) and the bottom shielding plate SP2 (described later) in plan perspective. It is formed. Further, the exhaust ports Oe formed on both the left and right sides of the bottom wall 111b are formed between the horizontal shielding plate SP1 (described later) and the bottom shielding plate SP2 (described later) in plan perspective. As shown in FIG. 3, a blower fan 115 is arranged directly above the intake port Os. When the blower fan 115 is driven, external air is sucked into the housing 111 through the intake port Os, and the heated air inside is discharged to the outside of the system from the exhaust port Oe by the air flow generated thereby. .. Further, a bottom shielding plate SP2 (described later) is arranged at the center of the upper surface of the bottom wall 111b.

Further, as shown in FIG. 4, an upper protrusion ST1 for preventing the second ferrite core FC2 from completely falling off from the ferrite core assembly 121 is provided inside (upper side) of the bottom wall 111b. Has been done.

The shoulder member 111c is a substantially rectangular frame, which is fitted on the upper side of the side wall 111a as shown in FIGS. 1 and 3, and covers the edge of the opening on the upper side of the side wall 111a. Then, as shown in FIG. 3, a protective frame 111d is attached to the lower side of the shoulder member 111c. As shown in FIG. 3, the protective frame 111d is attached to the shoulder member 111c by the protective frame flange portion FP (described later).

The protective frame 111d is a member that protects the outer circumference of the inner pot 130 and keeps the shape of the shoulder member 111c, and as shown in FIG. 3, mainly the inner pot accommodating portion PA and the protective frame flange portion. It is formed from FP. The inner pot accommodating portion PA is a bowl-shaped portion that covers the outer circumference of the inner pot 130. As described above, the protective frame flange portion FP is arranged on the lower side of the shoulder member 111c, and the shape of the shoulder member 111c is maintained by stretching the shoulder member 111c outward.

(2) Handle The handle 112 is a member provided for the user to carry the rice cooker 100 by hand, and is composed of a main body portion 112a and a shaft portion 112b as shown in FIG. The main body 112a has a U-shape as shown in FIG. The shaft portion 112b extends inward from both ends of the main body portion 112a as shown in FIG. In the rice cooker 100, the shaft portion 112b is a fitting portion (not shown) formed in the protective frame 111d through a hole (not shown) formed in the upper part of the center in the longitudinal direction of the side wall 111a. ) Is fitted.

(3) Insulation material The heat insulating material is wound around the side wall of the inner pot accommodating portion PA of the protective frame 111d and the outer circumference of the induction heating coil 113, and the heat generated from the inner pan 130 during rice cooking is generated outside the inner pot accommodating portion PA. It plays a role in suppressing the outflow to.

(4) Induction Heating Coil The induction heating coil 113 is an induction heating source that generates a magnetic field to induce and heat the inner pot 130, and as shown in FIGS. 3 to 6, mainly the first induction heating coil 113a. And a second induction heating coil 113b. As shown in FIGS. 4 and 5, the first induction heating coil 113a is arranged below the bottom wall portion of the inner pot accommodating portion PA of the protective frame 111d. As shown in FIGS. 4 and 5, the second induction heating coil 113b accommodates the inner pot outside the lower end of the side wall of the inner pot accommodating portion PA of the protective frame 111d so as to be separated from the first induction heating coil 113a. It is arranged along the curved surface of the portion PA.

(5) Ferrite Core Assembly 121 As shown in FIG. 6, four ferrite core assemblies 121 are arranged around the induction heating coil 113. As shown in FIG. 4, the ferrite core assembly 121 is composed of a first ferrite core FC1, a second ferrite core FC2, and a ferrite core holder 122. The first ferrite core FC1 and the second ferrite core FC2 are rectangular parallelepiped ferrite cores having the same dimensions. The first ferrite core FC1 plays a role of suppressing the magnetic field generated from the first induction heating coil 113a from leaking to the outside when energized, and faces the first induction heating coil 113a as shown in FIG. It is arranged so as to. The second ferrite core FC2 plays a role of suppressing the magnetic field generated from the second induction heating coil 113b from leaking to the outside when energized, and faces the second induction heating coil 113b as shown in FIG. It is arranged so as to. The first ferrite core FC1 and the second ferrite core FC2 are housed and fixed in the ferrite core holder 122 as shown in FIG. Further, between the first ferrite core FC1 and the second ferrite core FC2, an insulating adhesive (for example, curing at room temperature) that serves as an adhesive and a wall that prevents the first ferrite core FC1 from coming off downward. Mold silicone rubber, etc.) is injected.

The ferrite core holder 122 is formed with a first induction heating coil support portion (not shown) and a second induction heating coil support portion (not shown). The first induction heating coil support portion is a protrusion portion that serves to support the first induction heating coil 113a. The second induction heating coil support portion is a concave curved portion that serves to support the second induction heating coil 113b.

(6) Horizontal Shielding Plate The horizontal shielding plate SP1 is an annular member formed of a metal (for example, aluminum or the like), and a magnetic field leaking between the first ferrite core FC1 and the second ferrite core FC2 leaks to the outside. It plays a role of suppressing the. Here, as shown in FIG. 6, the central portion on the front side of the horizontal shielding plate SP1 is arranged so as to be located between the inner circumference and the outer circumference of the first induction heating coil 113a in the bottom view. .. Then, except for the central portion on the front side of the horizontal shielding plate SP1, as shown in FIG. 6, it is located between the outer circumference of the first induction heating coil 113a and the outer circumference of the second induction heating coil 113b in the bottom view. It is arranged in. Further, as shown in FIGS. 4 and 5, the lateral shielding plate SP1 is arranged so as to be located below the second induction heating coil 113b in the side view. The horizontal shielding plate SP1 is sandwiched between the bottom wall 111b and the ferrite core holder 122, as shown in FIGS. 6 and 7.

Here, in order to confirm the magnetic shielding performance of the horizontal shielding plate SP1, the magnetic field strength in the vertical direction with respect to the rice cooker 100 was measured by a loop antenna with three axes having a diameter of 2 meters. FIG. 8 shows the measurement results when the horizontal shielding plate SP1 is not arranged, and FIG. 9 shows the measurement results when the horizontal shielding plate SP1 is arranged. In FIGS. 8 and 9, the horizontal axis is frequency (MHz), the vertical axis is magnetic field strength (dB (μA)), and QP is the limit value of magnetic field strength in the vertical direction specified by the Radio Law. .. When the horizontal shielding plate SP1 was not arranged, as shown in FIG. 8, a margin of only +2.1 dB could be secured with respect to the limit value of the magnetic field strength in the vertical direction defined by the Radio Law. However, when the horizontal shielding plate SP1 was arranged, as shown in FIG. 9, it was possible to secure a margin of +6.3 dB with respect to the limit value of the magnetic field strength in the vertical direction specified by the Radio Law. ..

(7) Bottom shielding plate The bottom shielding plate SP2 has a role of suppressing leakage of the magnetic field generated from the first induction heating coil 113a to the outside and shielding heat. As shown in FIGS. 4 to 7, the bottom shielding plate SP2 is a plate-shaped member having a substantially rectangular shape and a central portion having a circular opening, and is formed of a metal (for example, aluminum or the like). As described above, the bottom shielding plate SP2 is arranged at the center of the upper surface of the bottom wall 111b. Further, the bottom shielding plate SP2 is arranged so as not to block the exhaust port Oe.

(8) Thermistor Thermistor 114 is a temperature sensor, and as shown in FIGS. 3 to 5, is upward through an opening formed in the central portion of the bottom wall portion of the inner pot accommodating portion PA of the protective frame 111d. It protrudes toward. The thermistor 114 is urged upward by an urging member such as a coil spring. That is, the thermistor 114 is in a state where it can freely appear and disappear along the vertical direction. Further, the thermistor 114 is incorporated in an inner pot detection sensor (not shown). The inner pot detection sensor is for determining whether or not the inner pot 130 exists in the rice cooker 100, and when the thermistor 114 is lowered to the lower end position, the detection signal is sent to the microcomputer of the control circuit board 119. Send. When the microcomputer receives the detection signal, it determines that the inner pot 130 exists in the rice cooker. If the microcomputer determines that the inner pot 130 does not exist in the rice cooker, the rice cooking operation is not started. By the way, the thermistor 114 is supported by a substantially disk-shaped cover member 127 as shown in FIGS. 3 to 6. The cover member 127 is screwed to the bottom wall of the inner pot accommodating portion PA of the protective frame 111d. Then, as shown in FIGS. 6 and 7, the cover member 127 is accommodated in the cover member accommodating portion 127a through the opening portion of the bottom shielding plate SP2.

(9) Blower fan As described above, the blower fan 115 is arranged directly above the intake port Os formed on the bottom wall 111b of the housing 111 so that the rotation axis is substantially along the vertical direction (FIG. FIG. 3). That is, when the blower fan 115 is driven, the outside air is sucked from the intake port Os, flows into the housing, and is sent upward as it is. The external air sent upward is supplied to the power supply circuit board 118, the control circuit board 119, and the like through the heat sink 116 to cool the members and the like.

(10) Heat sink The heat sink 116 is a component that efficiently exchanges heat with external air.

(11) Operation panel The operation panel 117 is for determining and executing the operation method of the rice cooker 100, and as shown in FIGS. 1 to 3, mainly the panel main body 117a, the pressing button BT, and the like. As described above, it is arranged on the upper side of the front side of the shoulder member 111c.

(12) Power Supply Circuit Board The power supply circuit board 118 is a board that constitutes a power supply circuit, and mounts some heat-generating components. As shown in FIG. 3, the power supply circuit board 118 is housed in the front space SPf of the housing 111 in the same manner as the control circuit board 119 described later.

(13) Control circuit board The control circuit board 119 is a board that constitutes a control circuit, and mounts electronic components such as a microcomputer. As shown in FIG. 3, the control circuit board 119 is housed in the front space SPf of the housing 111, and is arranged above the heat sink 116 and below the operation panel 117.

(14) Automatic winding type power cord unit The automatic winding type power cord unit 120 is composed of a power cord, an automatic winding mechanism (not shown), and the like, and is a casing as shown in FIGS. 3 and 6. It is housed in the space behind the body 111. The power cord consists of a plug OP and an electric wire (not shown). The plug OP is arranged at the tip of the electric wire. The electric wire is wound around an automatic winding mechanism so that it can be extended freely.

2. 2. Inner pot The inner pot 130 is a bowl-shaped pot that opens upward, is inserted through the opening of the shoulder member 111c, and is housed in the inner pot accommodating portion PA of the protective frame 111d with a predetermined gap. Here, the inner pot 130 is a multilayer body (clad material) of various aluminum alloys and stainless alloys, and can be induced and heated by the induction heating coil 113.

3. 3. Lid As shown in FIGS. 1 to 3, the lid 140 is mainly composed of an exterior body 141, an open / close button 142, a pressure adjusting mechanism 143, a reinforcing member (not shown), an inner lid 145, and a lever member 146. Has been done. It is rotatably attached to the main body 110 via a hinge mechanism 150.

As shown in FIGS. 1 to 3, the exterior body 141 is a substantially rectangular parallelepiped member, and houses an open / close button 142, a pressure adjusting mechanism 143, a lever member 146, and the like. Here, as shown in FIGS. 1 and 2, the open / close button 142 is arranged on the exterior body 141 so that the upper surface is exposed on the upper side of the exterior body 141. Further, here, the exterior body 141 is reinforced by a reinforcing member so as to be able to withstand the internal pressure during use. Further, an inner lid 145 is detachably arranged on the lower surface of the exterior body 141.

The open / close button 142 is a rectangular button with rounded corners for opening / closing the lid 140, and is arranged above the lever member 146. The open / close button 142 is urged upward by a coil spring (not shown).

The lever member 146 includes a contact plate portion (not shown), a pair of left and right extension plate portions (not shown) extending downward from the front side of the contact plate portion, and rearward from the lower portion of each extension plate portion. A metal plate member formed from a claw portion (not shown) extending toward the outside, which is pivotally supported by the exterior body 141 and is upwardly supported by a coil spring (not shown) at the rear end of the contact plate portion. Being urged towards. Here, when the open / close button 142 is pushed down by the user, the open / close button 142 comes into contact with a portion of the contact plate portion of the lever member 146 on the rear side of the rotation shaft.

Then, when the user intends to close the lid 140, the user does not need to operate the open / close button 142, and the lid 140 may be tilted toward the main body 110 as it is. At this time, the claw portion of the lever member 146 moves downward while contacting the inclined surface (not shown) formed on the shoulder member 111c. During this time, the lever member 146 rotates forward against the urging force of the coil spring. Then, when the claw portion reaches the claw receiving hole (not shown) formed in the shoulder member 111c, the claw portion is fitted into the claw receiving hole by the urging force of the coil spring. In this way, the lid 140 is closed. On the other hand, when the lid 140 is opened, the user pushes down the open / close button 142. Then, the lower end portion of the open / close button 142 abuts on the contact portion of the lever member 146, and the lever member 146 rotates forward against the urging force of the coil spring. At this time, the claw portion fitted in the claw receiving hole is pulled out from the claw receiving hole. Then, the lid 140 is lifted upward by the urging force of the hinge mechanism 150, and the lid 140 is opened.

The pressure adjusting mechanism 143 adjusts the pressure inside the inner pot 130 to 1.03 to 1.3 atm in a state where the lid 140 is closed and the pressure rice cooking operation is performed. Further, the pressure adjusting mechanism 143 regulates the rotation of the lever member 146 so that the lid 140 is not opened during the pressure rice cooking operation. In the present embodiment, the pressure adjusting mechanism is not particularly limited, and a conventional one may be adopted.

The reinforcing member is for increasing the strength of the lid 140. In the present embodiment, the reinforcing member is not particularly limited, and may be a metal plate itself or a metal plate having a complicated shape.

The inner lid 145 is a member for covering and sealing the upper part of the inner pot 130 as shown in FIG.

4. Hinge mechanism As described above, the hinge mechanism 150 attaches the lid 140 to the main body 110 so that the lid 140 is rotatable with respect to the main body 110. As described above, the hinge mechanism 150 urges the lid 140 toward the opening direction.

<Characteristics of Rice Cooker According to Embodiment of the Present Invention>
(1)
In the rice cooker 100 according to the embodiment of the present invention, the first induction heating coil 113a is arranged under the bottom wall portion of the inner pot accommodating portion PA of the protective frame 111d, and the second induction heating coil 113b is the first. It is arranged outside the lower end of the side wall of the inner pot accommodating portion PA of the protective frame 111d so as to be separated from the induction heating coil 113a. The first ferrite core FC1 that suppresses the magnetic field generated from the first induction heating coil 113a from leaking to the outside when energized is arranged so as to face the first induction heating coil 113a. The second ferrite core FC2 that suppresses the magnetic field generated from the second induction heating coil 113b from leaking to the outside when energized is arranged so as to face the second induction heating coil 113b. Further, at least a part of the lateral shielding plate SP1 that suppresses the magnetic field leaking between the first ferrite core FC1 and the second ferrite core FC2 from leaking to the outside is the outer periphery of the first induction heating coil 113a and the second induction heating. It is arranged so as to be located between the outer circumference of the coil 113b. Therefore, in this rice cooker 100, magnetic field shielding from the magnetic fields generated from the first induction heating coil 113a and the second induction heating coil 113b can be sufficiently performed, and the first ferrite core FC1 and the second ferrite core FC2 can be sufficiently shielded. An exhaust space can be secured between the side shielding plate SP1 and the lateral shielding plate SP1. Therefore, in the rice cooker 100, it is possible to efficiently exhaust the magnetic field generated from the induction heating coils 113a and 113b while sufficiently shielding the magnetic field.

(2)
In the rice cooker 100 according to the embodiment of the present invention, a metal annular member is adopted as the horizontal shielding plate SP1. Then, when the vertical magnetic field strength of the rice cooker 100 was measured with a three-axis loop antenna having a diameter of 2 meters, it was +6.3 dB with respect to the vertical magnetic field strength limit value specified by the Radio Law. It became clear that a margin could be secured. Therefore, in this rice cooker 100, magnetic shielding can be sufficiently performed against the magnetic field generated from the induction heating coil 113.

(3)
In the rice cooker 100 according to the embodiment of the present invention, the exhaust ports Oe are formed on the rear portion and the left and right side portions of the bottom wall 111b of the housing 111, but the exhaust gas formed on the left and right side portions of the bottom wall 111b. The mouth Oe is not blocked by the first ferrite core FC1, the second ferrite core FC2, the horizontal shielding plate SP1, and the bottom shielding plate SP2. Further, the exhaust port Oe formed at the rear portion of the bottom wall 111b is not blocked by the first ferrite core FC1, the second ferrite core FC2, and the bottom shielding plate SP2, and is slightly blocked by the horizontal shielding plate SP1. It's just that. Therefore, the exhaust space between the horizontal shielding plate SP1 and the bottom shielding plate SP2 can be communicated with the exhaust port Oe in a short distance, and the exhaust flowing between the horizontal shielding plate SP1 and the bottom shielding plate SP2 can be exhausted. It can be efficiently guided to the exhaust port Oe.

<Modification example>
(A)
In the rice cooker 100 according to the above embodiment, as a member for suppressing the magnetic field leaking between the first ferrite core FC1 and the second ferrite core FC2 from leaking to the outside, an annular metal (for example, aluminum) is used. Although the horizontal shielding plate SP1 which is a member has been adopted, for example, a metal lead wire may be adopted instead of the horizontal shielding plate SP1.

(B)
In the rice cooker 100 according to the previous embodiment, the central portion on the front side of the horizontal shielding plate SP1 is arranged so as to be located between the inner circumference and the outer circumference of the first induction heating coil 113a in bottom view. It was. However, the central portion on the front side of the horizontal shielding plate SP1 may be designed so that it can be located between the outer circumference of the first induction heating coil 113a and the outer circumference of the second induction heating coil 113b in the bottom view. In such a case, the entire horizontal shielding plate SP1 is arranged so as to be located between the outer circumference of the first induction heating coil 113a and the outer circumference of the second induction heating coil 113b in the bottom view.

(C)
In the rice cooker 100 according to the previous embodiment, the bottom shielding plate SP2 has a substantially rectangular shape. However, the shape of the bottom shielding plate SP2 is not particularly limited.

(D)
In the rice cooker 100 according to the above embodiment, at least a part of the exhaust port Oe formed in the rear portion of the bottom wall 111b of the housing 111 is between the horizontal shielding plate SP1 and the bottom shielding plate SP2 in plan perspective. It was formed. Further, the exhaust ports Oe formed on both the left and right sides of the bottom wall 111b were formed between the horizontal shielding plate SP1 and the bottom shielding plate SP2 in plan perspective. However, the exhaust port Oe may be formed on the outside of the bottom shielding plate SP2 in plan perspective.

(E)
In the rice cooker according to the previous embodiment, an annular member is adopted as the horizontal shielding plate SP1, but a partially annular member may be adopted as the horizontal shielding plate SP1.

(F)
In the rice cooker 100 according to the above embodiment, the second induction heating coil 113b is located outside the lower end of the side wall of the inner pot accommodating portion PA of the protective frame 111d so as to be separated from the first induction heating coil 113a. It was arranged along the curved surface of the accommodating portion PA. However, the second induction heating coil 113b may be arranged along the outer peripheral surface of the side wall of the inner pot accommodating portion PA.

(G)
In the previous embodiment, the present invention was applied to the rice cooker 100, but the present invention may be applied to other induction heating type heaters (induction heating type hot plate, electric kettle, electric kettle, etc.). ..

100: Rice cooker (cooking cooker)
111b: Bottom wall (bottom wall)
113: Induction heating coil 113a: First induction heating coil 113b: Second induction heating coil 130: Inner pot (heated body)
FC1: 1st ferrite core (1st magnetic shield)
FC2: 2nd ferrite core (2nd magnetic shield)
Oe: Exhaust port SP1: Horizontal shielding plate (third magnetic shield)
SP2: Bottom shield plate (4th magnetic shield)

Claims (3)

With the heated body,
A first induction heating coil arranged so as to face the heated body,
A second induction heating coil that is arranged outside the first induction heating coil so as to face the heated body and to be separated from the first induction heating coil.
The first magnetic shield portion arranged on the opposite side of the first induction heating coil on the side to be heated,
A second magnetic shield disposed on the opposite side of the second induction heating coil on the side to be heated,
With
An induction heater further comprising a third magnetically shielded portion that is at least partially disposed between the outer circumference of the first induction heating coil and the outer circumference of the second induction heating coil in plan perspective. The induction heater according to claim 1, wherein the third magnetic shield portion has an annular shape. A bottom wall portion on which an exhaust port is formed, which is arranged under the heated body, and
A fourth magnetically shielded portion disposed below the first magnetically shielded portion is further provided.
At least a part of the exhaust port is formed between the third magnetic shield portion and the fourth magnetic shield portion in plan perspective.
The induction heater according to claim 1 or 2.