JPS598296A - Coil for electromagnetic cooking device - 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 The present invention relates to a coil for an electromagnetic cooker. The present invention is particularly concerned with inserting seven pallets between the litz wires in a spiral electromagnetic cooking coil to further improve the reliability of the coil.

Conventionally, a coil for an electromagnetic cooker has been used by winding a Litz wire, which is made by twisting a plurality of enamelled wires, into a spiral shape. The present inventors have previously filed an application for a twisted wire obtained by blackening a twisted copper wire in a strongly oxidizing alkaline aqueous solution as an alternative to the Litz wire.

An electromagnetic cooker coil has the function of creating a magnetic field around the coil by passing a high-frequency current with a frequency of around 2010 (z), and creating an eddy current in a ferromagnetic material such as iron placed within the magnetic field. The present inventors have discovered that stranded copper wire can be formed with an oxide film to reduce the skin effect, and have used it in coils for electromagnetic cookers. We have also filed an application for stabilizing the quality of blackened copper stranded wire by applying and curing a strong impregnating varnish.The purpose of applying impregnating varnish is to prepare blackened copper wires or wind them into coils. In order to prevent damage caused by guides and coil winding jigs, we were able to provide highly reliable blackened litz wire.However, by applying impregnated varnish treatment, the reliability of the coil decreased. However, the process of impregnating varnish treatment was added, which caused an increase in cost.That is, the cost of impregnating varnish, application, and curing increased the cost.

Against this background, the present inventors have completed the present invention as a result of intensive development. The present invention will be explained in detail below.

In an electromagnetic cooker coil, a pulsed voltage is applied and the potential gradient between the litz wires is approximately 20V to 50V, and if the blackened coating peels off from the conductor, there is a possibility that a short circuit may occur and disconnection may occur. .

In order to prevent this short-circuit accident, the present invention is characterized in that a heat-resistant separator that can withstand temperatures of 170'C or more is interposed between the litz wires wound around the spiral coil. The heat-resistant separator may be present over the entire circumference of the lip wire, as shown in FIG. 1, or may be interposed only at the portion where the weld wire contacts. Further, the pallet may be partially interposed as shown in FIG.

The IAiJ heat 1 heat 1 beef separation used in the present invention is a film of polyimide, polyamideimide, polyamideimide ester, polyhydantoin, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, etc., or glass fiber, A film containing an inorganic substance such as glass powder can be used.

Furthermore, as the heat-resistant pallet, inorganic materials such as mica paper and glass fiber reinforced mica paper can be used.

In the blackened Litz wire used in the present invention, the following two methods can be used to form an oxide film on the copper wire. One is to form an oxide film on each copper wire before twisting it.
After that, there is a method of twisting the wire, and the other method is after making it into twisted copper wire,
There is a method of forming an oxide film. Either may be used. Here, a method for forming an oxide film on twisted copper wire will be described.

A strong alkali oxide aqueous solution can be used as the silver blackening treatment liquid for the oxidation treatment of the twisted copper wire. In other words, sodium chlorite, sodium nitrate, sodium nitrite, potassium dichromate, potassium permanganate, etc. can be used singly or in combination of two or more as acid arsenic agents in sumo wrestler alkaline and aqueous phosphate aqueous solutions. . Processing liquid temperature is 6
A temperature of 0 DEG C. to 100 DEG C. is sufficient, and the immersion time must be changed in consideration of the thickness of the copper oxide film and the degree of blackening treatment at the center of the stranded wire.

In addition, in order to lower the surface tension of the treatment liquid and improve the penetration of the treatment liquid into the inside of the stranded wire, water-soluble alcohols, polyhydric alcohols, or derivatives thereof may be added. I can do it.

Examples of organic solvents that improve the penetration of the treatment liquid into the inside of the stranded wires include ethanol, methanol, propatool isopropanol, n-butanol, isobutanol, amyl alcohol, pentanol, ethylene glycol, diethylene glycol, ethylene glycol monomethyl ether,
Ethylene glycol monomethyl ether acetate 1.
Diethylene glycol monomethyl ether and the like can be used. These organic solvents were added to the treatment solution: 11:
It is sufficient to add 3 to 20% by volume.

The blackened Litz wire produced in this manner has an oxide film with an insulation resistance of 106 to 108 Ω·m and an oxide film of 1.5 to 3.
0μnl is formed.

Therefore, it can sufficiently withstand the potential gradient between the respective strands constituting the litz wire.

However, when it is made into a coil, the potential gradient between the litz wires is 20V.
Since the voltage is about 50 V, peeling and falling of the blackened film causes a short circuit accident.

Incidentally, the separator according to the present invention can be installed between the litz wires at the time of coil forming. Alternatively, a method may be adopted in which the Litz wire is aligned with seven pallets during winding during the production of the Litz wire.

This will be explained below using examples.

(Example 1) 120 O, 18#IM annealed copper wires were twisted, and then a mixture of a sumo wrestler isoder aqueous solution (concentration 25%) and a sodium hypochlorite aqueous solution (20%) (however, 10vol 1% of isopropyl alcohol was added) ) containing a liquid tank (length 21+
) at a linear speed of m 7 m i n , followed by hot water washing and drying steps to obtain a blackened Litz wire.

When forming an electromagnetic cooker coil using this litz wire,
A 30 μin thick Kapton film was placed between the Litz wires as a separator over the entire coil. When voltage was applied to this coil to make it function, it was found that it could withstand long-term operation.

(Example 2) Everything except the following description is the same as Example 2.

When forming an electromagnetic cooker coil, mica pieces 1 (thickness x [IJ x height = 1 m x 5 m x 5 myn) were installed as block-shaped separators between the Litz wires, separated by 90 degrees. When voltage was applied to this coil to make it function, it was found that it could withstand long-term operation.

[Brief explanation of drawings]

Fig. 1 shows the case where the shield is used over the entire length between the Litz wires, and Fig. 2 shows the case where the wire is used partially between the Litz wires.
This shows the case where seven pallets are used. Figure 3 is a (yellow) cross-sectional view of the Litz wire and the Seven Valley Couple. In Figures 1, 2, and 3, 1.1' and Y' are blackened and .2', 2'' is a shibareku.

Claims (3)

[Claims] (1) An electromagnetic cooker coil made of a Litz wire obtained by blackening stranded copper wire in a strong oxidizing alkali aqueous solution, characterized in that seven pallets are provided between the Litz wires. (2) The coil for an electromagnetic cooker according to claim 1, characterized in that a polyimide, polyamitoimide, polyamitoimide ester, or polyesterimide film is used as the separator. (3) The coil for an electromagnetic cooker according to claim 1, characterized in that mica paper or glass fiber reinforced mica paper is used as the plater.