JPH03235307A - Transformer - Google Patents

Abstract

PURPOSE:To improve work efficiency and quality by providing the magnetic core which forms a closed magnetic circuit, with an insulating film of specified height. CONSTITUTION:A U-type magnetic core 3c and an I-type magnetic core 3b are joined to form the closed magnetic circuit of a transformer. Providing this magnetic core 3a or 3b or both magnetic cores with insulating films 7 equal to a joining gap, the work efficiency and quality are elevated for a transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to transformers used in various power supply equipment, video equipment, audio equipment, industrial equipment, and the like.

BACKGROUND OF THE INVENTION Recent technical demands for transformers include higher frequency, smaller size, and higher efficiency, and in response to these demands, an increasing number of transformers are using ferrite cores for their magnetic cores. In order to prevent performance deterioration of the ferrite cores constituting the magnetic circuit due to magnetic saturation, an air gap is generally provided at the butt joint surfaces of the ferrite cores.

In the case of an ICI type magnetic core, the air gap can be constructed by making the middle leg of the E shape shorter than the legs on both sides, or by applying a film of polyester resin or polypropylene resin to an arbitrary thickness at the butt part of the magnetic core. It is constructed by intervening.

By the way, a conventional transformer having a ferrite magnetic core has a structure as shown in FIGS. 6 and 7.

That is, a bobbin 1 with a winding 2 is inserted into a U-shaped magnetic core 3a made of ferrite, and the abutting surfaces of the U-shaped magnetic core 3& and the shaped magnetic core 3b are joined so as to sandwich the bobbin 1. There is. At this time, in order to fix the U-shaped magnetic core 31L and the shaped magnetic core 3b with a gap paper 4 interposed between the abutting surfaces to provide an air gap effect, the U-shaped tightening is performed using the metal fitting 5. Also, adhesive 6 was used. When fixing with adhesive 6, the gap paper 4 is cut into a square shape and the adhesive 6 is applied to the exposed end of the U-shaped core 3a (see FIG. 6).

Problems to be Solved by the Invention However, with such a conventional transformer configuration,
Inserting the gap paper 4 takes time and effort, and sometimes defects occur due to the gap paper 4 not being inserted or being misaligned. In addition, in the case of a small type, the winding 2 and the U-shaped magnetic core 3 &
There was also a problem in terms of quality.

The present invention solves the above-mentioned problems, and aims to provide a transformer with good workability and no quality problems.

Means for Solving the Problems In order to solve the above problems, the present invention provides an alternative to gap paper by providing an insulating film with a thickness equivalent to gear paper on one side of the ferrite magnetic core instead of inserting the gap paper. The configuration is such that

The structure is such that the winding wire and the ferrite magnetic core are insulated with a film.

Effect of the present invention With the above-described configuration, the insulating film provided on the surface of the ferrite magnetic core does not ensure the same magnetic circuit as in the state where there is an air gap at the butt joint surface, and as a result, performance decreases due to magnetic saturation. In addition, the coating on the winding portion of the ferrite core serves to prevent direct contact between the winding and the ferrite core.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4. Note that the same numbers used in the description of the conventional example are used for the same components as in the conventional example.

In the figure, 3a is a U-shaped magnetic core made of ferrite,
In the U-shaped magnetic core 31L, a pobbin 1 provided with a winding 2 is inserted into one leg of the U-shaped magnetic core 3a.

The abutting surfaces of the U-shaped magnetic core 3& and the shaped magnetic core 3b are joined so that the bobbin 1 is sandwiched between them.As shown in Fig. 1, the shaped magnetic core 3b is coated with a mixture by electrostatic coating. An insulating film 7 having the same thickness as the gap paper is provided using an insulating non-magnetic material such as an acrylic resin or an epoxy resin without any compounding.

The thickness of the insulating film 7 can be arbitrarily controlled by the electrostatic time and electrostatic voltage.

Furthermore, in the above-mentioned electrostatic coating, it is provided on the entire surface of the molded magnetic core 3b, but it is only necessary to apply it to the joint surface of the UI molded magnetic core.
A screen printing method may be used, or a depping method may be used.

What is the thickness of the insulating film 7 applied as described above?

Since it has the same air gap as the gap paper, the same magnetic circuit can be secured without inserting the gap paper into the abutting surfaces as in the conventional case.

For fixing the U-shaped magnetic core described above, the metal fittings 6 may be used to tighten the magnetic core as in the past, but when fixing with the adhesive 6, since there is no gap paper 4, a mixture of the adhesive 6 is used. It is better to set the particle size to, for example, 5 μm or less (the particle size of the adhesive mixture creates an air gap, and the variation in the particle size causes variations in performance).

In the embodiment shown in FIG. 1, the insulating film 7 was formed on the U-shaped magnetic core 3b, but as shown in FIG.
The same effect can be obtained even if the insulating film 7 is provided on a. The same applies to IC-shaped magnetic cores.

Furthermore, U-shaped magnetic core 3I! If it is set to the L side, when miniaturization is achieved, there is a risk that the winding 2 will not be able to maintain a space distance from the wall on the winding 2 side of the U-shaped magnetic core 3&, and the winding 2 will come into contact with the wall. Since the insulating film 7 applied to the U-shaped magnetic core 3 acts as an insulator, the product can be made with high safety and reliability.

Effects of the Invention As described above, according to the transformer of the present invention, since an insulating film is provided on the surface of the magnetic core, it is possible to maintain the same magnetic circuit as when conventional gap paper is inserted, and it is possible to maintain the same magnetic circuit for each transformer. There is no need to insert the gap paper each time. Therefore, by eliminating the gap paper insertion process, we are able to have an advantage over conventional transformers in terms of cost and mass production capability, and also have the excellent effect of solving quality problems caused by contact between the winding and the magnetic core. It's what you get.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the transformer of the present invention, Fig. 2 is a sectional view showing the state in which the magnetic core is tightened with a metal fitting, and Fig. 3 is a -1 of the embodiment of the same place. # A cross-sectional view showing the installed state, FIG. 4 is an explanatory view showing the state in which the magnetic core is fixed with adhesive, and FIG. FIG. 6 is a side view showing the application of adhesive to the abutting portions of magnetic cores in a conventional example, and FIG. 7 is a sectional view showing the structure of a conventional transformer. 1...Bobbin, 2...Winding, 3&...
・U-shaped magnetic core, 3b...Engine-shaped 8 cores, 7...
・Insulating film.

Claims (1)

[Claims] A transformer in which two magnetic cores are joined to form a closed magnetic circuit, and an insulating film corresponding to an arbitrary gap thickness is formed on one or both of the magnetic cores.