JPS63259991A - Induction heating cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field).

The present invention relates to an induction heating cooker that inductively heats a limb heating body by passing a high frequency current through a heating coil.

(Prior art) Conventionally, the heating coil of an electromagnetic cooker for heating an iron pot is made of a spiral Litz wire formed by twisting together about 20 insulated conductive wires with a wire diameter of about 0.5 mm. A coil wound around 20 tangs is used, but since the resistivity of the load is high when heating an iron pot, sufficient heating can be achieved by supplying a high frequency current of about 20 KHz, and the heating coil Losses were not an issue. However, when heating an aluminum pot used in general households, aluminum has a low resistivity and is a non-magnetic material, so the number of turns of the heating coil must be increased and the frequency of the high-frequency current must be increased. must be made higher. In this case, the number of turns of the heating coil is quadrupled to 80 turns, and the frequency of the high-frequency current is doubled! 'J 50 KHz is negative 6:j
It is known that the resistivity of iron is comparable to that of an iron pot.

(Problem to be Solved by the Invention) When the heating coil is manufactured by winding wires as described above, as the frequency of the supplied high-frequency current increases, the current flows near the surface of each cable wire. The concentrated skin effect increases, and as the number of turns increases, the magnetic flux density generated around the cable increases, so the interlinkage magnetic flux of each cable varies greatly depending on the positional relationship of the cable, and each This causes an imbalance in the amount of current flowing through the wires, increasing loss in the heating coil and significantly reducing efficiency, causing the heating coil itself to generate heat and making it impossible to properly heat the pot. be. Making the wire diameter of the litz wire thinner can alleviate the disadvantages mentioned in 1- to some extent, but reducing the wire diameter dramatically increases the price, and in order to obtain the same cross-sectional area, This has the disadvantage that the number of wires must be increased, which further increases the price. Furthermore, as mentioned above, when the wire diameter of the strands is reduced, the number of strands increases, so when connecting the lead wire or terminal to the terminal attachment part at the end of the litz wire, it is necessary to remove the insulation coating of each strand. This becomes very troublesome, and when removing the insulating coating using chemicals, capillarity tends to occur, which causes the insulating coating to be peeled off to unnecessary parts, making the work even more troublesome.

Therefore, an object of the present invention is to reduce the loss of the heating coil even when a high-frequency current is passed through the heating coil, thereby efficiently heating the object to be heated, which can be manufactured at low cost, and which allows terminal attachment at the terminal end. To provide an induction heating cooker that allows easy connection work at the parts.

[Structure of the Invention] (Means for Solving the Problems) The present invention is an apparatus for induction heating a heating element by passing a high frequency current of an audio frequency or higher through a heating coil. The heating coil is characterized in that the heating coil is wound around the body with an insulating layer interposed therebetween.

(Function) According to the two-legged means, since the ribbon-shaped conductor has a larger surface area than a litz wire, there is little increase in loss even when high-frequency, two-frequency current is passed through it, and it is possible to Because there is little elementalization of the interlinkage magnetic flux of each ribbon-shaped conductor, the unbalance of the current flowing through each ribbon-shaped conductor is minimized, and the loss of the heating coil is significantly reduced. Furthermore, the cost is lower than the conventionally used Litz wire, which is made by twisting together a large number of small diameter wires, and the connection work is easier. It is easy to manufacture and can be manufactured at low cost.

(Example) Examples of the TSL of the present invention will be described below with reference to FIGS. 1 to 4. In FIG. 1, 1 is a DC power supply circuit, which is composed of a bridge rectifier 3 for rectifying an AC power supply 2 and a 914 Namekawa capacitor 4. A high frequency inverter 5 for converting direct current into high frequency current is connected to this DC power supply l, and a heating coil 6 for induction heating a pot placed on a top plate (not shown) is connected to this high frequency inverter 5.

The heating coil 6 will be explained in detail below. 7 has a thickness of 35μ
The conductor is a ribbon-shaped conductor made of copper foil having a thickness of 1.5 mm, and an insulating layer 8 made of a heat-fusible insulating material is coated on one side of the conductor. This insulating layer 8 is, for example, an insulating face (
For example, Toshiba Chemical's TVC-3626) is used. In this way, a ribbon-shaped conductor 7 with an insulating layer 8 coated on the − side
For example, 7 pieces of
The heating coil 6 is formed by winding the coil in turns, removing it from the jig 9, and then heating it at a predetermined temperature to cause the insulating layer 8 and the ribbon-shaped conductor 7 to self-fuse and integrate with each other. As shown in FIG. 2, the ends of the heating coil 6 are aligned so that the ribbon-like conductor 7 is stepped, and the lead wires 10 and 11 are connected thereto by soldering. The heating coil 6 described above may be wound as is with a predetermined width, for example, 4 mm, but it may also be wound with a ribbon-shaped conductor having a width of 500 mm, for example, and then cut into a predetermined width with a cutting machine or the like after winding. .

In the above-mentioned embodiment configured in this way, since a plurality of ribbon-shaped conductors 7 coated with an insulating layer 8 are simply layered and wound around the jig 9, a large number of elements with small wire diameters can be used. Compared to the conventional method using litz wire made by twisting wires together, it is easier to manufacture and can be manufactured at a much lower cost. Since the ribbon-shaped conductor 7 can have a very large surface area, even if the skin effect is increased by supplying a high-frequency current to the heating coil 6 to heat an aluminum pot, it can be made of copper wire with a circular cross section. Unlike litz wires, there is no increase in loss, so aluminum pots can be heated efficiently. In addition, since the magnetic flux density is dense on the concentric circle of the heating coil 6, the magnetic flux interlinking in the width direction of each thin ribbon-shaped conductor is equal, and each ribbon-shaped conductor has a substantially uniform density. A high frequency current flows through the heating coil, and therefore the aluminum pot can be heated efficiently without increasing loss, unlike when a high frequency current is passed through a heating coil made of litz wire.

In the configuration described in [-], the heating coil 6 is integrated by melting the insulating layer 8, so that heat can be efficiently radiated from the heating coil 6. Temperature rise can be reduced by 1-1.

FIGS. 5 and 6 show a second embodiment of the present invention, and only the parts different from the first embodiment will be described below. That is, in this second embodiment, a tap or lead wire 12 is provided in the middle of the heating coil 6, and when an iron pot is heated by switching a switch 13, a high frequency current is applied between the lead wires 10 and 12 to heat the aluminum pot. When heating, use lead wire 1
A high-frequency current is applied between 0 and 11, and each strand of the lead wire 12 is connected to the ribbon-shaped conductor 7 at the tap portion as shown in FIG. The ribbon-shaped conductor 7 and the insulating layer 8 are sandwiched between them, and after the heating coil 6 is wound, solder is poured into the contact portion to connect them to each other.

7 and 8 show a third embodiment of the present invention, and only the parts different from the first embodiment will be explained. That is, a first heating coil 14 and a second heating coil 15 are connected to the high frequency inverter 5 via a switch 16, and the first heating coil 14 is a 20-turn litz wire spiral as in the conventional case. The second heating coil 15
was manufactured by winding the ribbon-shaped conductor 7 with 40 turns in the same manner as the heating coil 6 of the first embodiment, and the first and second heating coils 15 and 16 were stacked in two stages. It is configured to be installed below a top plate (not shown) on which a pot is placed. In this device, when heating an iron pot, the switch 16 is switched so that contacts c and a are closed, and a high-frequency current is applied only to the first heating coil 14 to heat the aluminum pot. switch 1 in case
6 contacts c and b are switched to close, and the first
A high frequency current is supplied to the DC circuits of the second heating coils 14 and 15.

In this case, when the second coil 15 heats the aluminum pot, the same effect as in the first embodiment is achieved.

In addition, in each of the embodiments described, the heating coil 6 and the second heating coil 15. Instead of the insulating layer 8, a heat-sealable insulating sheet 17 as shown in FIG.
They may be sandwiched between each other.

[Effects of the Invention] As is clear from the following description, the present invention applies a high frequency current higher than an audible frequency to a heating coil to inductively heat an object to be heated. Because it is characterized by being wound through an insulating layer to form a heating coil, it is easier to manufacture than conventional wires that use litz wires, which are made by twisting together a large number of wires with a small diameter. It is easy and very inexpensive to manufacture, and the ribbon induction 7 and body are thin and can have a very large surface area, so even if a high frequency current is supplied to the heating coil to heat an aluminum pot, the skin effect will increase. Unlike Litz wire, which is made of copper wire with a circular cross section, there is no increase in loss, so aluminum pots can be heated efficiently.Furthermore, the magnetic flux density is the same in the concentric circles of the heating coil, so it is thin. The magnetic flux interlinking in the width direction of each ribbon-shaped conductor is equal, and an approximately uniform high-frequency current flows through each ribbon-shaped conductor. Therefore, heating coils made of litz wire This method has various excellent effects such as being able to efficiently heat an aluminum pot without increasing loss unlike when a high-frequency current is passed through the aluminum pot.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is an electric circuit diagram, FIG. 2 is a perspective view of a heating coil,
FIG. 3 is a perspective view showing the relationship between the ribbon-shaped conductor and the insulating layer;
Fig. 4 is a perspective view showing the manufacturing process of the heating coil, Figs. 5 and 6 show a second embodiment of the present invention, Fig. 5 is an electric circuit diagram, and Fig. 6 is a diagram of the heating coil. partial perspective view,
7 and 8 show a third embodiment of the present invention, FIG. 7 is an electric circuit diagram, FIG. 8 is a side view showing the arrangement of heating coils, and FIG. 9 is a diagram of the third embodiment of the present invention. Third example showing another example
It is a figure equivalent figure. In the drawing, 1 is a DC power supply circuit, 5 is a high frequency inverter, and 6 is a DC power supply circuit.
is a heating coil, 7 is a ribbon induction body 7, 8 is an insulating layer, 1
5 is a second heating coil, and 13 and 16 are switches. Figure 1 Figure 2 Figure 3 Figure jP, Figure 4 Figure 5 Figure 6 Condolence 7 Figure also 8 Figure Pl 9 Figure

Claims (1)

[Claims] 1. In a heating coil that inductively heats a heated object by passing a high-frequency current higher than an audio frequency through a heating coil, the heating coil is made by winding a plurality of thin ribbon-shaped conductors with an insulating layer interposed therebetween. An induction heating cooker characterized by comprising: 2. Claims characterized in that a heat-fusible insulating material is used for the insulating layer, and the insulating layer and the ribbon-shaped conductor are fused and integrated with each other by heating after winding to form a heating coil. The induction heating cooker according to item 1.