JPH05307995A - Work coil for induction heater and induction heater using work coil - Google Patents

Abstract

PURPOSE:To improve heat efficiency and make the whole size compact. CONSTITUTION:An inverter 10 is connected to a work coil 30 through a current path 20. The work coil is put in solution to be heated Q and the inverter 10 is of resonant type. The work coil 30 is made of coil and heating plate. Heat generated in the work coil 30 is all used effectively to heat solution Q.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work coil for an induction heating device, which is provided in a liquid to be heated so as to obtain high thermal efficiency, and an induction heating device using the work coil.

[0002]

2. Description of the Related Art Cookers utilizing induction heating are becoming popular.

This one is capable of highly efficient cooking by exciting a work coil by a high frequency of about several kHz or more and inductively heating an iron pot via an alternating magnetic field generated in the work coil. An inverter is often used as the high frequency power supply at this time.

[0004] In addition, since the pot that contains the liquid to be heated generates heat, this product has good thermal efficiency and is clean as compared with a general cooker that uses a flame such as gas or kerosene or a heating wire as a heat source. In addition, since it does not use a high temperature heat source, it is safe and has good cooking quality. In particular, when used for processing deep-fried foods such as tempura and fries, high-precision temperature control is possible, and there is no risk of the oil temperature becoming excessive, so there is little deterioration of the oil, and there is less frying residue in the oil. There is an advantage that the product value of the product is less likely to be reduced by being carbonized and attached to the product.

[0005]

According to such a conventional technique, good heat efficiency can be obtained as compared with a conventional cooker using a flame, a heating wire, etc., but heating is performed by indirect heating through an iron pot. Therefore, the heat loss generated in the work coil cannot be effectively utilized, and in the iron pan, the outer surface side becomes the highest temperature due to the effect of the skin effect, so the loss due to heat dissipation cannot be avoided, and therefore However, there is a problem that there is still room for improvement in thermal efficiency. Note that this is a problem that can be generally and generally applied to not only the cooking device but also the induction heating device used for other purposes.

In view of the problems of the prior art, the object of the present invention is to make it possible to directly put the whole into the liquid to be heated, thereby further improving the thermal efficiency. And to provide an induction heating device using the same.

[0007]

The structure of the first invention according to the present application for achieving the above object is a coil formed by winding a coil wire in a flat plate shape, and heat generation arranged in the vicinity of the coil. The gist is that the plate and the plate are assembled together so that the whole can be put into the liquid to be heated.

The heating plate may have holes for adjusting the heat generation distribution.

The structure of the second invention comprises the work coil according to the first invention, a liquid tank into which the work coil can be put, and an inverter for exciting the work coil, and the inverter uses the inductance of the work coil for resonance. The main point is that it is a type inverter.

The inverter and the work coil can be connected to each other via an electric path composed of a pair of conductors that are closely contacted and parallel to each other.

[0011]

According to the structure of the first aspect of the invention, the coil can generate an alternating magnetic field interlinking with the heating plate by being excited by the high frequency current, and the heating plate correspondingly generates heat. However, at this time, since the whole is put in the liquid to be heated, the entire amount of heat generated on both sides of the heating plate can be effectively used for heating the liquid to be heated, and the heat loss in the coil is also reduced. , Can be effectively used.

When the heat generating plate has holes, the distribution of the eddy current generated in the heat generating plate changes, and the heat generation distribution of the heat generating plate can be adjusted arbitrarily.

According to the structure of the second invention, since the inverter is a resonance type inverter utilizing the inductance of the work coil, a maximum current due to resonance can be applied to the work coil, and therefore the entire structure is improved. It is possible to make it smaller.

By using an electric path made up of conductors that are in close contact with each other and are parallel to each other, the self-inductance of the electric path can be minimized and the circuit loss can be minimized.

[0015]

Embodiments Embodiments will be described below with reference to the drawings.

The induction heating device comprises an inverter 10 and a work coil 30 which is put into the liquid to be heated Q in a liquid tank 41 via an electric path 20 (FIG. 1).

The inverter 10 includes a rectifier circuit 11 for connecting a three-phase power source AC and a switching transistor TR1.
, TR2 and the control circuit 12 are the main members.
A smoothing capacitor Ca is provided on the output side of the rectifier circuit 11.
And a series circuit of transistors TR1 and TR2 are connected in parallel. Diodes D1 and D2 having opposite polarities are connected in parallel to the transistors TR1 and TR2, respectively. The connection point of the transistors TR1 and TR2 is connected to the output terminal T11, and a current detector CT is provided on the way to the output terminal T11. The capacitors C1 and C2 are connected to the collector side of the transistor TR1 and the emitter side of the transistor TR2, respectively, and the output sides of the capacitors C1 and C2 are both connected to the output terminal T12.

The output of the current detector CT is connected to the control circuit 12, and the bases of the transistors TR1 and TR2 are also connected to the control circuit 12.

The electric circuit 20 is connected to the output terminal T of the inverter 10.
11 and T12 are connected to the input terminals T41 and T42 of the work coil 30 installed in the liquid tank 41. The electric path 20 is formed by closely adhering a pair of conducting bands 21 and 22 in parallel via an insulating film 23 (FIG. 2), and the insulating film 23 is provided on both sides of the conducting bands 21 and 22 in order to increase the creepage distance. It is projected. It should be noted that, regardless of FIG. 2, the electric circuit 20 may have any specific structure as long as it uses a pair of conducting bands 21 and 22 that are closely attached and parallel to each other. For example, the conductors 21, 22 are
By insulating-molding the whole, the insulating film 23
Can be omitted.

The work coil 30 includes holding members 31, 3
The coil 33 and the heat generating plate 34 are integrally assembled via 2, 32, ... (FIGS. 3 and 4).

The coil 33 is obtained by twisting 10 or more copper wires having a diameter of about 0.5 mm and insulating them, and winding them in a spiral shape to form a flat plate. In addition,
The coil wire may be a copper pipe. Coil 33
Is the liquid to be heated Q by the appropriate varnish impregnation treatment.
It shall be insulated so that it can be put into

The holding member 31 includes a plurality of legs 31a, 31a.
It is a plate-like member that radially forms ... And has a large-diameter through hole 31b formed in the center thereof. Also, each leg 3
A screw hole 31c for fixing the holding member 32 is formed at the tip of 1a, and further, if necessary, the heat generating plate 3
An attachment hole 31d for fixing the No. 4 is formed. Further, the coil 33 is provided at the tip and the base of the specific leg 31a.
Through holes 31e, 31e for penetrating the coil wire corresponding to the winding start and winding end are formed.

The other holding members 32, 32 ...
It is provided corresponding to one leg 31a, 31a .... Each holding member 32 is a strip-shaped member having a hook 32a formed at one end and a leg portion 32b with a mounting hole 32b1 formed at the other end. In each holding member 32, the hook 32a is hooked on the through hole 31b of the holding member 31, and the leg portion 32 is pulled from the machine screw 32c.
The coil 33 is attached to the holding member 31 so that the coil 33 is sandwiched by screwing b.

The heat generating plate 34 is a plate material having its peripheral portion folded back in a frame shape, and has a hole 34a formed in the central portion. In addition, elongated holes 34b, 3 and 3 are formed around the hole 34a.
4b ... Are formed in a double circle shape. The heating plate 34
Are formed with mounting holes 34c, 34c ... Corresponding to the mounting holes 31d, 31d.

The heat generating plate 34 includes set screws 34d, 34d ...
And the holding member 31 and the coil 33 are integrally assembled with each other to form the work coil 30. The heating plate 3
4 is assembled close to and parallel to the coil 33. The heat generating plate 34 is preferably made of an iron plate material having high magnetic permeability so that it can efficiently generate heat by interlinking with the alternating magnetic field generated by the coil 33, and the holding members 31, 32, 32. It is preferable to use a stainless steel material, an aluminum material, or the like in order to suppress unnecessary heat generation.

The work coil 30 is installed in the liquid tank 41 of the main body casing 40 (FIG. 5) and put into the liquid Q to be heated in the liquid tank 41 for use. However, work coil 3
It is preferable that 0 is detachable from the liquid tank 41 for convenience of cleaning. The liquid to be heated Q is, for example, oil for processing deep-fried food, and the liquid tank 41 is provided with a deep-frying pan 41a with a discharge valve 41b. It should be noted that the inverter 10 may be incorporated in the main body housing 40, or may be installed separately from the main body housing 40.

The inverter 10 is controlled by the control circuit 12.
By alternately conducting the transistors TR1 and TR2, a high frequency current can be passed through the work coil 30. That is, when the transistor TR1 is turned on, a current in the direction of the transistor TR1, the output terminal T11, the input terminal T41, the work coil 30, the input terminal T42, the output terminal T12, and the capacitor C2 flows through the work coil 30, while the transistor TR2. When conducting
Because the current flows in the direction of the capacitor C1, the output terminal T12, the input terminal T42, the work coil 30, the input terminal T41, the output terminal T11, and the transistor TR2, the direction of the current flowing in the work coil 30 can be alternately inverted. is there.

The transistor T by the control circuit 12
The control frequency f of R1 and TR2 is set to about 20 to 50 kHz, and the capacitance C / 2 of the capacitors C1 and C2 and the inductance L of the coil 33 of the work coil 30 are f = 1 / (2π (LC ) ^1/2 ) shall be satisfied. That is, the inverter 10 is a resonance type inverter in which the capacitors C1 and C2 and the coil 33 of the work coil 30 are in a resonance state and the inductance L of the work coil 30 is utilized.

In this way, when a high-frequency current is applied to the coil 33 of the work coil 30, an alternating magnetic field is generated in the coil 33, so that the heat generating plate 34 interlinks with the alternating magnetic field to generate heat and generate heat. The heating liquid Q can be heated. The amount of heat generated by the work coil 30 depends on the inverter 1
0 output current. Therefore, the control circuit 12
Compares the output current detected by the current detector CT with a set value from a setter (not shown) and variably controls the conduction periods of the transistors TR1 and TR2.
The amount of heat generated by the work coil 30 can be arbitrarily changed, and the liquid temperature of the liquid to be heated Q can be optimally controlled.

In the above description, the holes 34a, 34b, 34b ... Formed in the heat generating plate 34 are for adjusting the heat generation distribution in the heat generating plate 34. That is, hole 3
4a, 34b, 34b ... make the heat generating plate 34 lose physical uniformity and make the distribution of the eddy current generated inside the heat generating plate 34 non-uniform due to the alternating magnetic field generated by the coil 33. Because you can. Therefore, the hole 34
a, 34b, 34b, etc. are arbitrary in shape, size, arrangement, etc. according to the use application such as realizing a uniform heat generation distribution over a wide area or locally achieving heat generation over a small area. Can be changed to.
Further, the specific shape of each member including the number of legs 31a, 31a ... Of the holding member 31 and the number of used holding members 32 is
Any change can be made as long as the coil 33 and the heat generating plate 34 can be integrally assembled into a predetermined shape.

[0031]

As described above, according to the first invention of this application, the coil and the heat generating plate are integrally assembled,
By allowing the whole to be put into the liquid to be heated, the heat generating plate can be made to generate heat by induction heating by the high-frequency current passing through the coil, and the heat at this time is heated from both sides of the heat generating plate. Since it can be transferred to the liquid and the heat loss generated in the coil can be effectively used, there is an excellent effect that the overall thermal efficiency can be maximized.

According to the second invention, by combining the work coil according to the first invention and the resonance type inverter, the thermal efficiency is extremely good, and as a whole,
The effect is that it can be made significantly smaller.

[Brief description of drawings]

[Figure 1] Overall circuit diagram

FIG. 2 is a perspective view of a main part configuration

FIG. 3 is an exploded perspective view of a work coil

FIG. 4 is a central sectional view of the work coil.

[Fig. 5] Schematic diagram of overall configuration

[Explanation of symbols]

 Q ... Liquid to be heated 10 ... Inverter 20 ... Electrical path 21, 22 ... Conductive band 30 ... Work coil 33 ... Coil 34 ... Heating plate 34a, 34b ... Hole 40 ... Main body case 41 ... Liquid tank

Claims (4)

[Claims] 1. A coil formed by winding a coil wire in a flat plate shape and a heat generating plate arranged in the vicinity of the coil are integrally assembled so that the whole can be put into a liquid to be heated. A work coil for an induction heating device. 2. The work coil for an induction heating device according to claim 1, wherein the heat generating plate has holes for adjusting a heat generation distribution. 3. The work coil according to claim 1 or 2, comprising: a liquid tank into which the work coil can be charged; and an inverter for exciting the work coil, the inverter comprising: An induction heating device characterized by being a resonant inverter that utilizes inductance. 4. The induction heating device according to claim 3, wherein the inverter and the heater element are connected to each other through an electric path formed of a pair of conducting bands that are closely contacted and parallel to each other.