JPH03116705A - Manufacture of molded transformer - Google Patents

Abstract

PURPOSE:To facilitate setting a fibrous reinforcing material in the gap between a low-voltage coil and a high-voltage coil by compressing the reinforcing material in the direction of its outside diameter being reduced, and besides keeping the compressed state with the encirclement of a released film. CONSTITUTION:A fibrous reinforcing material 7 is compressed in the direction of its outside diameter being reduced, and is put in the gap 12 between a low- voltage coil 3 and a high-voltage coil 11 in a state heat the above-mentioned compressed state is kept by the encirclement of a released film 9 through the medium of a high-voltage side shield 8. On this occasion, the setting in the gap 12 can be done easily as the fibrous reinforcing material 7 is in a compressed state. After that, the released film 9 is melted and cut off by electrifying a heating wire 10 before injecting resin into a metal mold, the heating wire 10 is extracted and removed, and the fastening force is removed. Consequently, the fibrous reinforcing material 7 expands by its resiliency, and fills in the gap 12. Then, the gap inside the high-voltage coil 11 disappears.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a molded transformer.

[Prior Art] A molded transformer can be divided into the following two types based on the structure of the molded resin body.

A: Resin such as epoxy resin filled with powder filler such as silica.

B. Resin such as epoxy resin filled with fibrous reinforcing material such as glass fiber.

The present invention is directed to the latter type B molded transformer.

A conventional B-type molded transformer has a low-voltage coil and a high-voltage coil placed coaxially in a casting mold with an air gap between them, and an air gap between the low-voltage coil and the high-voltage coil. was manufactured by injecting resin such as epoxy resin into a casting mold and molding the mold filled with fibrous reinforcing material such as glass fiber.

[Problems to be Solved by the Invention] However, filling the ring-shaped gap between the low-voltage coil and the high-voltage coil with a fibrous reinforcing material requires a lot of manpower and time, has poor workability, and is expensive. There was a problem with the high price.

An object of the present invention is to provide a method for manufacturing a molded transformer that allows easy setting of a fibrous reinforcing material in the gap between a low-voltage coil and a high-voltage coil.

[Means for Solving the Problems] A detailed explanation of the present invention for achieving the above object is as follows.

The invention according to claim (1) is characterized in that a low-voltage coil and a high-voltage coil are coaxially arranged in a casting mold, and a gap between the low-voltage coil and the high-voltage coil is provided with elastic fibrous reinforcement. In the method for manufacturing a molded transformer, in which a molded transformer is manufactured by injecting resin into the casting mold with the reinforcing material inserted, the fibrous reinforcing material is compressed in a direction to reduce its outer diameter; A compressed state is maintained in the gap between the low voltage coil and the high voltage coil while being surrounded by a release film, and the release film is cut before injecting the resin into the casting mold. The invention of claim (2) is characterized in that the fibrous reinforcing material in a compressed state is expanded by expanding the fibrous reinforcing material in a compressed state in claim (1). It is characterized in that it is attached in advance and set in the casting mold together with the low voltage coil.

[According to claim (1), the fibrous reinforcing material is compressed in a direction that reduces its outer diameter, and the compressed state is maintained by surrounding it with a release film, so that its wall thickness is thin. Therefore, it can be easily set in the gap between the low voltage coil and the high voltage coil.

Further, after setting, the release film is cut and the fibrous reinforcing material is expanded, so that the gap between the low voltage coil and the high voltage coil can be easily filled.

In claim (2), since the fibrous reinforcing material in a compressed state is attached to the outer periphery of the low-voltage coil in advance, the fibrous reinforcing material can be set in the casting mold together with the low-voltage coil, greatly improving workability. can. Furthermore, the fibrous reinforcing material can be attached and compressed after the winding of the low-voltage coil, and workability is improved in this respect as well.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a state in which the transformer is set in a casting mold in the method for manufacturing a molded transformer according to this embodiment. In the figure, 1 is the core of the casting mold, 2 is a fibrous reinforcing material such as glass fiber arranged around the outer periphery of the core 1, 3 is a low voltage coil arranged around the outer periphery of the fibrous reinforcing material 2, and 4 5 is a release film placed on the outer periphery of the fibrous reinforcing material 4; 6 is a low-voltage side shield placed on the outer periphery of the release film 5; Reference numeral 7 denotes an elastic fibrous reinforcing material such as glass fiber arranged around the outer periphery of the low-pressure side shield 6. The fibrous reinforcing material 7 is
It has a structure in which it is compressed in a direction to reduce its outer diameter, and its compressed state is maintained by surrounding it with a release film 9 via a high-pressure side shield 8. A heating wire 10 for cutting, such as a nichrome wire, is arranged in the axial direction on the inner surface of the release film 9 at at least one location in the circumferential direction. Reference numeral 11 denotes a high-voltage coil coaxially arranged outside the low-voltage coil 3 with a gap 12 interposed therebetween, and 13 and 14 denote fibrous reinforcing materials such as glass fibers arranged on the inner and outer peripheries of the high-voltage coil 11. As the release film 5.9, for example, a release-treated Mylar film, a fluorine-based film, or the like is used. As the low-voltage side shield 6 and the high-voltage side shield 8, for example, Cu, A° C. foil, carbon paper, or the like is used.

Further, the low voltage side shield 6 and the high voltage side shield 8 are connected to the fifth
As shown in the figure, an insulating sheet 15 is interposed between the wrap portions to prevent the formation of a closed circuit. Since the wrap portion of the high-pressure side shield 8 is reduced due to expansion of the fibrous reinforcing material 7, the wrap length is set in consideration of this. As shown in FIG. 6, the high-pressure side shield 8 has hollow portions 8a at multiple locations so that the circumference can be extended without obstructing the expansion of the fibrous reinforcing material 7.
is provided.

Therefore, in this embodiment, when manufacturing the molded transformer, the compressed fibrous reinforcing material 7 is placed in the gap 12 between the low voltage coil 3 and the high voltage coil 11. In this case, since the fibrous reinforcing material 7 is in a compressed state, it can be easily set into the void 12.

Thereafter, the heating wire 10 is energized to melt and cut the release film 9. After cutting, the heating wire 10 is pulled out and removed. In this way, the force that was tightening the elastic fibrous reinforcing material 7 is removed, and the fibrous reinforcing material 7 expands due to its elasticity, creating a gap as shown in FIGS. 2 and 3. 12, and the void inside the high voltage coil 11 disappears. If a material with good slippage is used as the release film 9, the expansion of the internal fibrous reinforcing material 7 will not be inhibited. On the other hand, the high-pressure side shield 8 between the release film 9 and the fibrous reinforcing material 7 also has a curved portion 8a which expands as the fibrous reinforcing material 7 expands, increasing the circumference. does not inhibit the expansion of

FIG. 4 is a wiring diagram showing the positional relationship of the electrical parts of the molded transformer formed by the method of this embodiment. In the figure, 3a and 3b are an inner outlet terminal and an outer outlet terminal of the low voltage coil 3, and 11a.

Reference numerals 11b denote an inner outlet terminal and an outer outlet terminal of the high voltage coil 11. The low voltage side shield 6 is connected to the outer outlet terminal 3b of the low voltage coil 3, and the high voltage side shield 8 is connected to the inner outlet terminal 11a of the high voltage coil 11.

The molded transformer thus formed is coated with a release film 5.
, 9 and the mold resin, after the resin hardens, there is a gap between the reinforced plastic layer made of the fibrous reinforcing material 4 and the resin and the release film 5, and between the reinforced plastic layer made of the fibrous reinforcing material 13 and the resin. Although minute gaps are created between the release film 9 and the release film 9, these areas are areas where the electric field between the low voltage coil 3 and the low voltage side shield 6 and between the high voltage coil 11 and the high voltage side shield 8 is extremely small. Therefore, no discharge occurs. Although a large electric field is applied between the low-voltage side shield 6 and the high-voltage side shield 8, there are no voids or unimpregnated parts in this area, and there is no peeling at the interface between the live part and the resin, so no discharge occurs. does not occur.

Note that the voltage Vε between the low voltage coil 3 and the low voltage side shield 6 and between the high voltage coil 11 and the high voltage side shield 8 needs to be small. For this reason, it is desirable that each coil β, 11 has a foil-wound structure. In this way,
■ε is a voltage range of O to 1 turn.

A portion 9A of the release film 9 on the high voltage coil 11 side that is cut by the heating wire 10 becomes a defective portion. The width of the missing part 9A is
Calculated m + 2πe (when the heating wire 10 is set at two locations, m
+πe). Here, m is the size of the melt due to heating, and e is the size of the bulge caused by the melt.

In order to compensate for such a defective portion 9A, as shown in FIG.
It is preferable to insert the local release film 17 through the tube 6. The heat insulating sheet 16 is for preventing the local release film 17 from being fused and cut when the heating wire 10 is heated, and is removed together with the heating wire 10 after the release film 9 is fused.

The fibrous reinforcing material 7 can also be provided as follows. That is, on the winding machine for manufacturing the low-voltage coil 3, after the formation of the low-voltage coil 3, the fibrous reinforcement 4. Release film 5
．． At the stage of winding the low-pressure side shield 6, the fibrous reinforcing material 7 is wrapped and compressed, or compressed while being wrapped,
Thereafter, a high-voltage side shield 8 is provided on the outer periphery with a hollow part 8a attached, and a release film 9 is wrapped around the heating wire 10 at one or more places on the outer periphery, thereby controlling the compressed state of the fibrous reinforcing material 7. to be maintained.

In the above embodiment, the release film 9 was cut by the heating wire 10, but as shown in FIG.
Alternatively, the tension strip 18 for cutting is integrally attached to the planned cutting location, the lower end thereof is folded back and raised upward, and the release film 9 is cut by pulling the tip 18A of the folded portion. good. In this case, the local release film 17 may be disposed between the cutting tensile filament 18 and the high-pressure side shield 8 without intervening the heat insulating sheet 16, unlike in FIG.

[Effects of the Invention] As explained above, according to the method for manufacturing a molded transformer according to the present invention, the following effects can be obtained.

In claim (1), the fibrous reinforcing material is compressed in a direction that reduces its outer diameter, and the compressed state is maintained by surrounding it with a release film, so that its wall thickness becomes thinner and lower pressure is achieved. This has the advantage that it can be easily set in the gap between the coil and the high voltage coil.

Further, after setting, the release film is cut and the fibrous reinforcing material is expanded, so that the gap between the low voltage coil and the high voltage coil can be easily filled.

In claim (2), since the fibrous reinforcing material in a compressed state is attached to the outer periphery of the low-voltage coil in advance, the fibrous reinforcing material can be set in the casting mold together with the low-voltage coil, greatly improving workability. can. Further, the fibrous reinforcing material allows installation and compression work to be carried out subsequent to the winding work of the low-voltage coil, which also has the advantage of improving workability.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 and 2 are cross-sectional views of main parts of a molded transformer in the order of steps in the method of manufacturing a molded transformer according to the present invention,
Figure 3 is a vertical cross-sectional view of one side of the molded transformer;
The figure is a wiring diagram of the molded transformer, Figure 5 is a cross-sectional view of each shield in the molded transformer, and Figure 6 is a cross-sectional view of the main part showing the folded state of the high voltage side shield used in the molded transformer. 7 is a cross-sectional view showing an improved example of the heating wire interposed part of the molded transformer, and FIG. 8 is a perspective view of the main part showing another example of the release film cutting means used in the molded transformer. be. DESCRIPTION OF SYMBOLS 1... Core, 2.4.7, 13.14... Fibrous reinforcement material, 3... Low voltage coil, 5.9... Peeling film, 6... Low voltage side shield, 8...・High pressure side shield,
10... Heating wire for cutting, 11... High voltage coil, 15
...Insulation sheet, 16...Insulation sheet, 17...
Release film for local area, 18... tensile filament for cutting,
18A...Tip. Figure 2 Figure 2 Figure 2 Figure 2

Claims (2)

[Claims] (1) A low-voltage coil and a high-voltage coil are arranged coaxially in a casting mold, and an elastic fibrous reinforcing material is inserted into the gap between the low-voltage coil and the high-voltage coil. In the method for manufacturing a molded transformer, in which the molded transformer is manufactured by injecting resin into the casting mold, the fibrous reinforcing material is compressed in a direction to reduce its outer diameter, and the compressed state is the same as that of the release film. the air gap between the low-voltage coil and the high-voltage coil in a state of being maintained in an enclosed state, and in a compressed state by cutting the release film before injecting the resin into the casting mold; A method for manufacturing a molded transformer, characterized by expanding a fibrous reinforcing material. (2) According to claim (1), the compressed fibrous reinforcing material is attached in advance to the outer periphery of the low-voltage coil, and is set in the casting mold together with the low-voltage coil. manufacturing method of molded transformer.