JP2003282232A - Induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating device capable of heating metals with high conductivity and low permeability such as aluminum or copper, and improving the reliability of a control circuit. <P>SOLUTION: The induction heating device such as an induction heating cooker having equal to or more than two heating coils is provided with a heating coil 34 used to heat only the metals with high conductivity and low permeability. In this structure, it is not necessary to detect a load, to switch the inductance of the heating coil, and to switch the capacitance of a resonant capacitor, thus the control circuit is simplified, so that the reliability of the induction heating device is improved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating apparatus represented by an induction heating cooker, and more particularly to an induction heating apparatus capable of heating a metal having high conductivity and low magnetic permeability such as aluminum or copper. It is a thing.

[0002]

2. Description of the Related Art Various techniques for heating a metal having a high electric conductivity and a low magnetic permeability such as aluminum and copper have been introduced in an induction heating apparatus, and Japanese Utility Model Laid-Open No. 61-36987 is cited as an example. A brief description will be given with reference to FIGS.

Reference numeral 1 is a top plate on the upper surface of the main body, and heating coils 2 are arranged on the back surface of the top plate 1 so as to face each other with a space therebetween. The heating coil 2 is formed by stacking a plurality of spirally wound coils 2a and 2b on top of each other, and connecting the inner end of the coil 2a and the outer end of the coil 2b to each other, thereby increasing the number of turns. There is. FIG. 3 shows a control circuit, which has a resonance capacitor 15a having a small capacity and a resonance capacitor 15b having a large capacity, and the capacities thereof can be switched according to the detection result of the load detection circuit 21.

In the load detection circuit 21, the material of the object to be heated 4 is iron or non-magnetic stainless steel (in this conventional example, it is described as iron or non-magnetic stainless steel, but it goes without saying that it may include enamel or magnetic stainless steel. If it is determined that there is none, the switch 16 is turned off and the switch 17 is turned on. That is, the heating coil 2 (coil 2a) having a small number of turns and the resonance capacitor 15b having a large capacity constitute a resonance circuit, and the resonance circuit is excited by turning on / off the transistors 13 and 14.

When it is determined that the material of the object to be heated 4 is aluminum or copper, the switch 16 is turned on and the switch 17 is turned off. That is, the heating coil 2 (coil 2
b) and the resonance capacitor 15a having a small capacitance form a resonance circuit, and the resonance circuit is excited by turning on / off the transistors 13 and 14.

In this way, a high-frequency current flows through the heating coil 2, and the high-frequency magnetic field emitted from the heating coil 2 inductively heats the pan 4.

[0007]

However, in the above-mentioned conventional structure, since load detection, heating coil inductance switching, resonance capacitor capacity switching, etc. are required, the control circuit becomes complicated and reliability is lowered. was there.

The present invention solves the above-mentioned conventional problems, and in an induction heating device capable of heating a metal having a high conductivity and a low magnetic permeability such as aluminum or copper, an induction heating device having improved control circuit reliability. The purpose is to provide.

[0009]

In order to solve the above-mentioned conventional problems, an induction heating apparatus of the present invention is an induction heating apparatus such as an induction heating cooker having two or more heating coils.
A heating coil dedicated to heating a metal having high conductivity and low magnetic permeability is provided.

With this configuration, when heating an object to be heated such as aluminum or copper, load detection, heating coil inductance switching, resonance capacitor capacity switching, etc. are not required, and the control circuit is simplified and reliability is improved. It is possible to provide the induction heating device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 is an induction heating apparatus such as an induction heating cooker having two or more heating coils, in which a metal having high conductivity and low magnetic permeability is exclusively used for heating. By providing a coil, when heating an object to be heated such as aluminum or copper, load detection, heating coil inductance switching, resonant capacitor capacity switching, etc. are not required, simplifying the control circuit and improving reliability. It is possible to provide an induction heating device having improved temperature.

According to the second aspect of the invention, the heating coil on the low rated output side is dedicated to heating a metal having a high conductivity and a low magnetic permeability, so that an ordinary heating coil dedicated to heating an iron-based metal is used. (The object to be heated is iron, enamel, magnetic stainless steel, non-magnetic stainless steel, etc.) It is possible to suppress the heat generation of the heating coil that is exclusively used for heating a metal having a high electric conductivity and a low magnetic permeability, which has a large heat generation.

According to a third aspect of the present invention, a heating coil dedicated to heating a metal having a high conductivity and a low magnetic permeability and a heating coil dedicated to heating an iron-based metal are selectively used in one drive circuit. By driving, the occupied space does not increase because the drive circuit is shared, and the cost can be reduced.

According to a fourth aspect of the present invention, the rated output of a heating coil dedicated to heating a metal having high conductivity and low magnetic permeability is set lower than the rated output of a heating coil dedicated to heating an iron-based metal. This makes it possible to heat metals with high conductivity and low magnetic permeability that generate more heat than ordinary heating coils (iron, enamel, magnetic stainless steel, non-magnetic stainless steel, etc.) that are used exclusively for heating iron-based metals. The heat generation of the coil can be suppressed.

According to the fifth aspect of the present invention, the heating coil, which is exclusively used for heating the metal having the high conductivity and the low magnetic permeability, is arranged at the central rear portion of the main body, so that the heating coil is frequently used and is suitable for induction heating. The heating coil corresponding to the heating element is near the front and the frequency of use is low, and the heating coil corresponding to the object to be heated, which is not suitable for induction heating, is deep and the usability is improved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings, using an induction heating cooker as an example of an induction heating device.

(Embodiment 1) First, a schematic configuration of an induction heating cooker will be described with reference to FIG. Two heating coils 32 and 33 corresponding to iron, enamel, magnetic stainless steel, non-magnetic stainless steel, etc. are provided in front of the main body 31, and high conductivity and low magnetic permeability such as aluminum and copper are provided in the central rear part of the main body 31. A heating coil 34 dedicated to heating metal is provided. Further, the roaster 35, the drive circuits 36 and 37 of the heating coils 32, 33 and 34 arranged on the opposite side of the roaster 35, the cooling fan 38 at the back thereof, the intake port 40 behind the top plate 39, and the exhaust port. 41 is provided.

The heating coil 32 is driven by a drive circuit 36. Further, the heating coils 33 and 34 are driven by the drive circuit 37. In this case, a resonance capacitor matching each of the heating coils 33 and 34 is provided, and the resonance capacitor is switched according to the heating coil used. The heating coils 33 and 34 are driven by the drive circuit 37.
Since they are shared, they cannot be heated at the same time.

In the heating coil 34, the material of the object to be heated is made of a metal such as aluminum or copper having a high electric conductivity and a low magnetic permeability, but it is possible to induction heat a material unsuitable for such an induction heating. In addition, the current flowing through the heating coil 34 and the number of turns are increased to increase the strength of the magnetic field, and the drive circuit 37
The oscillation frequency is set to 40 kHz or higher to reduce the skin depth and facilitate induction heating of the object to be heated.

The heating coil 34 has the lowest rated output among the three heating coils. This is because the heating coil 34 has a large current and a large number of turns and a large amount of heat generation, and therefore, if the rated output is increased, the temperature rise of each part may exceed the limit.

In this structure, the heating coils 32, 3
A high-frequency magnetic field is generated from 3, 34, and this is given to a heated body (not shown) placed on the top plate 39 to generate an eddy current, and the heated body is induced by self-heating due to eddy current loss. Be heated.

With the above structure, when heating an object to be heated such as aluminum or copper, load detection and heating coil inductance switching (resonance capacitor capacity switching are not required), and the control circuit is simplified and reliability is improved. It is possible to provide an induction heating device having improved temperature.

Further, since the heating coil 34, which is exclusively used for heating a metal having high conductivity and low magnetic permeability, has a low rated output, heat generation of the heating coil 34 can be suppressed.

Further, by driving the heating coil 34 dedicated to heating a metal having a high conductivity and a low magnetic permeability and the heating coil 33 dedicated to heating an iron-based metal by one driving circuit 37, a driving circuit 37 is provided. Because the shared space does not increase,
Also, the cost can be reduced.

Further, by disposing the heating coil 34, which is exclusively used for heating a metal having a high conductivity and a low magnetic permeability, in the central rear portion of the main body 31, it is possible to cope with a heated object which is frequently used and suitable for induction heating. The heating coil is near the front and is used less frequently, and the heating coil corresponding to the object to be heated, which is not suitable for induction heating, is deep and the usability is improved.

In this embodiment, the heating coils 33 and 34 are used.
Although each is provided with a resonance capacitor, it is also possible to share the resonance capacitor and switch only the inductances of the heating coils 33 and 34. In this case, it is not necessary to detect the load and switch the capacitance of the resonance capacitor.
(Inductance switching of the heating coils is required.) In the present embodiment, the driving circuits 37 for the heating coils 33 and 34 are shared, and it is not possible to heat them at the same time. May be. In this case, heating can be performed simultaneously, and load detection, heating coil inductance switching, and resonance capacitor capacity switching are all unnecessary.

The number of heating coils is not limited to three, and it goes without saying that the number of heating coils is not particularly limited as long as the effects of this embodiment can be obtained.

[0028]

As described above, according to the present invention, in an induction heating apparatus capable of heating a metal having a high conductivity and a low magnetic permeability such as aluminum or copper, the induction heating apparatus having improved control circuit reliability. Can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an induction heating device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an induction heating cooker in a conventional example.

FIG. 3 is a diagram showing a connection state of heating coils in a conventional example.

FIG. 4 is a configuration diagram of a control circuit in an induction heating cooker in a conventional example.

[Explanation of symbols]

31 body 32, 33, 34 heating coils 37 Drive circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuyuki Aihara             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hiroo Izumi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 3K051 AB06 AC07 AC10 AD28 AD37                       CD17 CD43                 3K059 AA08 AB27 AC07 AC10 AD28                       AD40 BD13

Claims (5)

[Claims] 1. An induction heating apparatus having a heating coil having two or more ports, the induction heating apparatus having a heating coil dedicated to heating a metal having high conductivity and low magnetic permeability. 2. The induction heating device according to claim 1, wherein the heating coil on the low rated output side is dedicated to heating a metal having high conductivity and low magnetic permeability. 3. An induction heating device for selectively driving a heating coil dedicated to heating a metal having a high conductivity and a low magnetic permeability and a heating coil dedicated to heating an iron-based metal with a single drive circuit. 4. The induction heating according to claim 3, wherein the rated output of the heating coil dedicated to heating the metal having high conductivity and low magnetic permeability is lower than the rated output of the heating coil dedicated to heating the iron-based metal. apparatus. 5. A heating coil, which is exclusively used for heating a metal having a high electric conductivity and a low magnetic permeability, is arranged in the central rear portion of the main body.
[4] The induction heating device according to any one of [4].