JP2007311244A - Induction-heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent uncomfortable beat sounds for a user from occuring from a load such as a cooking pan during use of an induction heating cooker by interference caused on an inverter circuit and a heating coil by switching noises generated at a switching power supply. <P>SOLUTION: This induction-heating cooker is provided with the body unit 6 having a heating coil 1, a rectifying circuit 5, the inverter circuit 2 which is connected to the rectifying circuit 5 and which generates a high-frequency current in the heating coil 1, and a control circuit 8 for controlling heating by the heating coil 1, and with a sub-unit 7 having the switching power supply 3 for supplying a DC constant voltage to the control circuit 8, a first noise filter 4a connected between a commercial power supply 13 and the rectifying circuit 5, and a second noise filter 4b connected between the commercial power supply 13 and the switching power supply 3. The main body unit cabinet 11 to constitute the body unit 6 is constituted of a conductive magnetic body to prevent noise interference between the body unit 6 and the sub-unit 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an induction heating cooker, in particular, an induction circuit including a commercial power source as an input and an inverter circuit that generates a high-frequency current in a heating coil, and a switching power source that receives a commercial power source and supplies a DC constant voltage to a control circuit or the like. It relates to a cooking device.

The induction heating cooker in the prior art includes an inverter circuit that inputs a commercial power source and generates a high-frequency current in a heating coil, and a switching power source that inputs a commercial power source and supplies a DC constant voltage to a control circuit or the like. It was.
In such a configuration, switching noise generated by the switching power supply interferes with the inverter circuit and the heating coil, and an unpleasant beat sound is generated from the load such as the cooking pan when the induction heating cooker is used.

In a microwave oven, it has already been proposed to provide a noise filter case separately from the microwave oven body and to provide a noise filter inside the case (see, for example, Patent Document 1).
However, this prior art is not a technique related to the switching noise of the induction heating cooker, and cannot solve the above-described problems with the induction heating cooker.

Japanese Utility Model Publication No. 5-43498

  The present invention is intended to prevent switching noise generated in a switching power source from interfering with an inverter circuit and a heating coil, and to reduce an unpleasant beat sound generated from a load when the induction heating cooker is used. .

  In the induction heating cooker according to the present invention, a main body having a heating coil, a rectifier circuit, an inverter circuit that is connected to the rectifier circuit and generates a high-frequency current in the heating coil, and a control circuit that controls heating by the heating coil. A unit, a switching power supply for supplying a constant DC voltage to the control circuit, a first noise filter connected between a commercial power supply and the rectifier circuit, and a second connected between the commercial power supply and the switching power supply And a noise shielding means for preventing noise interference between the main unit and the subunit.

  According to the present invention, switching noise generated in a switching power supply can be prevented from interfering with an inverter circuit and a heating coil, and unpleasant beat noise generated from a load when using an induction heating cooker can be reduced. .

Embodiment 1 FIG.
A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the induction heating cooker in the first embodiment.

FIG. 1 shows the configuration of an induction heating cooker according to Embodiment 1 of the present invention. In FIG. 1, the induction heating cooker includes noise filters 4a and 4b connected to a commercial power supply 13, and a rectifier circuit 5 connected to the noise filter 4a. The inverter circuit 2 connected to the rectifier circuit 5, the heating coil 1 connected to the inverter circuit 2, the switching power source 3 connected to the noise filter 4b, the control circuit 8, the operation unit 9, and the display unit 10 And have.
The noise filters 4 a and 4 b prevent switching noise generated in the inverter circuit 2 or switching noise generated in the switching power supply 3 from leaking to the power supply line of the commercial power supply 13.
The rectifier circuit 5 converts alternating current of the commercial power supply 13 into direct current. The inverter circuit 2 switches the switching element at several tens of kHz and generates a high frequency current in the heating coil 1. By causing the heating coil 1 to generate a high-frequency current, an induction current is generated at the bottom of the load such as a cooking pot, and the load is heated.
The switching power supply 3 generates a DC constant voltage to be supplied to the control circuit 8 from the commercial power supply voltage by switching the switching element at about 100 kHz. The control circuit 8 controls the heating of the induction heating cooker based on information from the operation unit 9 and information from the inverter circuit 2. The user operates the operation unit 9 to adjust the heating power during cooking. The display unit 10 displays thermal power based on information from the operation unit 9 or the control circuit 8.

  A high frequency current of several tens of kHz is generated in the heating coil 1 by the inverter circuit 2. When other high-frequency components are superimposed on this high-frequency current, a roaring sound uncomfortable for the user may be generated from a load such as a cooking pan. Here, since the switching power supply 3 is also switched at a high frequency, the switching noise may interfere with the inverter circuit 2 and the heating coil 1 and may be superimposed on a high-frequency current of several tens of kHz flowing through the heating coil 1.

  The induction heating cooker according to the first embodiment includes a main unit 6 having a main unit casing 11 and a subunit 7 having a subunit casing 12. The main body unit 6 includes a main body unit housing 11 provided with an inverter circuit 2, a heating coil 1, a control circuit 8, an operation unit 9, and a display unit 10. The subunit 7 has a subunit housing 12 provided with a first noise filter 4a, a second noise filter 4b, and a switching power supply 3. Here, the main unit housing 11 includes a conductive magnetic material such as an iron alloy or an aluminum alloy, and is connected to a ground as a ground potential portion.

Considering the interference path of the switching noise generated in the switching power supply, two paths can be considered.
The first interference path is a path that passes through the current lines of the second noise filter 4b, the first noise filter 4a, the rectifier circuit 5, the inverter circuit 2, and the heating coil 1. As described above, the noise filters 4a and 4b are for blocking switching noise, and the high frequency components of the switching noise can be significantly attenuated by passing through the noise filters 4a and 4b. Further, since the first interference path includes the first noise filter 4a and the second noise filter 4b, the switching noise generated in the switching power supply 3 hardly reaches the inverter circuit 2 and the heating coil 1. .
The noise blocking ability of the noise filter may be reduced due to the influence of heat and leakage magnetic flux generated by other components. There are a heating coil 1 and an inverter circuit 2 as heat-generating parts of the induction heating cooker.
However, in the configuration according to the first embodiment, the heating coil 1 and the inverter circuit 2 are arranged in separate units from the first noise filter 4a and the second noise filter 4b, and thus are not affected by heat.
There is a heating coil 1 as a component that generates a leakage magnetic flux that lowers the noise blocking ability of the noise filter (because the leakage flux of other components is small, the noise blocking ability of the noise filter hardly decreases).
However, since the main unit housing 11 includes a conductive magnetic material and is connected to the ground as a ground potential portion, the leakage magnetic flux generated in the heating coil 1 is shielded by the main unit housing 11 and is used as the ground potential portion. Absorbed by earth. For this reason, the noise filters 4a and 4b are not affected by heat and leakage magnetic flux generated by other components, so that the noise blocking ability is not lowered.

The second interference path is due to electromagnetic waves emitted from the switching power supply 3 to the surrounding space. In order to prevent this second interference path, the conventional induction heating cooker requires a shield plate, or restrictions have been placed on the arrangement of the switching power supply.
However, in the configuration according to the first embodiment, electromagnetic noise generated from the switching power supply 3 disposed in the subunit 7 is shielded by the main unit unit housing 11 in which the inverter circuit 2 and the heating coil 1 are disposed. The circuit 2 and the heating coil 1 are not reached. The main unit housing 11 made of a conductive magnetic body functions as noise shielding means for preventing noise interference between the main unit 6 and the subunit 7.

  As a result, switching noise generated by the switching power supply 3 is prevented from interfering with the inverter circuit 2 and the heating coil 1, and unpleasant beat noise generated from a load such as a cooking pan when the induction heating cooker is used is reduced. can do.

  According to the first embodiment of the present invention, the heating coil 1, the rectifier circuit 5, the inverter circuit 2 connected to the rectifier circuit 5 and generating a high-frequency current in the heating coil 1, and the heating by the heating coil 1 are controlled. A main unit 6 having a control circuit 8 for performing the operation, a switching power supply 3 for supplying a constant DC voltage to the control circuit 8, a first noise filter 4a connected between the commercial power supply 13 and the rectifier circuit 5, A main unit housing that includes a subunit 7 having a power source 13 and a second noise filter 4b connected between the switching power source 3 and constitutes the main unit 6 and houses the heating coil 1 and the inverter circuit 2. The body 11 is formed of a conductive magnetic body connected to the ground potential portion, and noise that prevents noise interference between the main unit 6 and the subunit 7 Since the shielding means is provided, switching noise generated by the switching power supply is prevented from interfering with the inverter circuit and the heating coil, and an unpleasant beat sound generated from a load such as a cooking pan when the induction heating cooker is used. Can be reduced.

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a block diagram showing the configuration of the induction heating cooker in the second embodiment. FIG. 3 is a perspective view illustrating the configuration of the induction heating cooker according to the second embodiment. FIG. 4 is a block diagram showing another configuration of the induction heating cooker in the second embodiment.
In the second embodiment, the configuration other than the specific configuration described here has the same configuration contents as the configuration in the first embodiment described above, and exhibits the same operation. In the drawings, the same reference numerals indicate the same or corresponding parts.

  In FIG. 2 which shows the structure of the induction heating cooking appliance in Embodiment 2 by this invention, a different point from Embodiment 1 is that the main body unit 6 has several inverter circuits 2a and 2b and several heating coils 1a and 1b. It is. The first inverter circuit 2a is connected to the rectifier circuit 5 and generates a high-frequency current in the first heating coil 1a. The second inverter circuit 2b is connected to the rectifier circuit 5 and generates a high-frequency current in the second heating coil 1b. The first heating coil 1a heats a first load such as a cooking pot, and the second heating coil 1b heats a second load such as another cooking pot, or the first heating coil and the second heating coil. Heat the same load, such as a common cooking pot, with a heating coil.

As described above, in the conventional induction heating cooker, in order to prevent the switching noise generated by the switching power supply 3 from interfering with the inverter circuit and the heating coil, there are restrictions on the arrangement of the switching power supply, the inverter circuit, and the heating coil. It was. In particular, in an induction heating cooker having a plurality of heating coils and a plurality of inverter circuits, the restriction is very large.
Therefore, as in the second embodiment, the inverter circuits 2a and 2b, the heating coils 1a and 1b, the control circuit 8, the rectifier circuit 5, the operation unit 9, and the display unit 10 are provided, and the conductive magnetism is provided. By constituting the induction heating cooker with the subunit 7 having the body unit 6 covered with the body 11 having the body, the first noise filter 4a, the second noise filter 4b, and the switching power supply 3. The restrictions on the arrangement of the switching power supply 3, the inverter circuits 2a and 2b, and the heating coils 1a and 1b are significantly reduced.

FIG. 3 is a perspective view for explaining a case where the variation of products having different arrangements of the plurality of heating coils 1 is increased. As a product in which the arrangement of the plurality of heating coils 1 is different, a case where the heating coils 1 are arranged side by side, a case where the heating coils 1 are arranged side by side, a case where the sizes of the plurality of heating coils 1 are different, and the like can be considered.
Thus, in the product in which the arrangement of the plurality of heating coils 1 is different, the variation of the main body unit 6 in which the arrangement of the plurality of heating coils is different is increased and combined with one type of subunit 7. Since the switching power supply 3 is a separate unit from the main unit 6 having the inverter circuit 2 and the heating coil 1, there are less restrictions on the arrangement of the inverter circuit 2 and the heating coil 1, and the main units differ in the arrangement of the plurality of heating coils 1. Variations of the unit 6 can be easily increased.

  In the above embodiment, the second inverter circuit 2b is connected to the rectifier circuit 5 similarly to the first inverter circuit 2a. However, as shown in FIG. 4, the second inverter circuit 4b is connected to the second rectifier circuit. The second rectifier circuit 5b may be connected to the third noise filter 4c, and the third noise filter 4c may be connected to the commercial power supply 13.

  According to the second embodiment of the present invention, in the configuration of the first embodiment, the main body unit 6 includes a plurality of heating coils 1a and 1b and a plurality of inverter circuits 2a and 2b. Even in a multi-mouth induction heating cooker capable of heating, the switching noise generated by the switching power supply 3 can be prevented from interfering with the inverter circuits 2a, 2b and the heating coils 1a, 1b, and a load such as a cooking pan when using the induction heating cooker It is possible to reduce the unpleasant beat noise generated by the user, and to reduce the restrictions on the arrangement of the heating coil and the inverter circuit, making it easy to increase product variations.

Embodiment 3 FIG.
A third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of the induction heating cooker in the third embodiment.
In the second embodiment, the configuration other than the specific configuration described here has the same configuration as the configuration in the first embodiment or the second embodiment described above, and exhibits the same operation. It is. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 5 which shows the structure of the induction heating cooking appliance in Embodiment 3 by this invention, a different point from Embodiment 1 and Embodiment 2 is that surge absorption circuit 14 is connected between a commercial power source and a noise filter. It is.
The surge absorbing circuit 14 is for preventing the product from being broken when a steep voltage surge occurs in the power line of the commercial power supply 13. The inverter circuit 2 that generates a large voltage and a large current is likely to malfunction due to the steep voltage surge and malfunction.

In the third embodiment, since the surge absorption circuit 14 is connected immediately after the commercial power supply 13 and the noise filters 4a and 4b are connected thereafter, the steep voltage surge generated in the power supply line of the commercial power supply 13 is the inverter circuit 2. This does not occur in the main unit 6 that arranges.
Therefore, a stable operation that is not affected by a steep voltage surge generated in the power supply line of the commercial power supply 13 is possible. Further, failure due to a steep voltage surge generated in the power line of the commercial power supply 13 is mainly in the subunit 7, so that replacement and repair are easy.

  According to the third embodiment of the present invention, in the configuration in the first or second embodiment, the subunit 7 is provided between the commercial power source 13 to which the induction heating cooker is connected and the noise filters 4a and 4b. Since the surge absorbing circuit 14 is provided, stable operation is possible without being affected by the surge generated in the commercial power supply, and replacement and repair are facilitated.

It is a block diagram which shows the structure of the induction heating cooking appliance in Embodiment 1 by this invention. It is a block diagram which shows the structure of the induction heating cooking appliance in Embodiment 2 by this invention. It is a perspective view explaining the structure of the induction heating cooking appliance in Embodiment 2 by this invention. It is a block diagram which shows the other structure of the induction heating cooking appliance in Embodiment 2 by this invention. It is a block diagram which shows the structure of the induction heating cooking appliance in Embodiment 3 by this invention.

Explanation of symbols

1, 1a, 1b Heating coil, 2, 2a, 2b Inverter circuit, 3 Switching power supply, 4, 4a, 4b Noise filter, 5, 5a, 5b Rectifier circuit, 6 Main unit, 7 Sub unit, 8 Control circuit, 9 Operation Part, 10 display part, 11 body unit case, 12 sub unit case, 13 commercial power supply, 14 surge absorption circuit, 15 ground.

Claims (4)

  A main body unit having a heating coil, a rectifier circuit, an inverter circuit connected to the rectifier circuit and generating a high-frequency current in the heating coil, a control circuit for controlling heating by the heating coil, and a DC constant current in the control circuit. A subunit having a switching power supply for supplying a voltage, a first noise filter connected between a commercial power supply and the rectifier circuit, and a second noise filter connected between the commercial power supply and the switching power supply. An induction heating cooker comprising a noise shielding means for preventing noise interference between the main unit and the subunit.   The induction heating cooker according to claim 1, wherein the noise shielding means is a casing made of a conductive magnetic material connected to a ground.   The induction heating cooker according to claim 1 or 2, wherein the main unit has a plurality of heating coils and a plurality of inverter circuits. The induction heating cooker according to any one of claims 1 to 3, wherein the subunit has a surge absorption circuit between a commercial power source to which the induction heating cooker is connected and a noise filter.

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