JPH02214102A - Resin-molded coil - Google Patents

Abstract

PURPOSE:To prevent an exfoliation from being caused at an interface between an inner periphery material and a molding resin by a method wherein an exposed part is formed at an inside corner part of a bobbin and this coil is united by a molding resin layer with which a whole part other than the exposed part is covered. CONSTITUTION:An inner-periphery-material exposed part 6 is exposed in such a way that a corner part of a glass-fiber-reinforced epoxy-resin inner periphery material 1 is not covered with a molding resin 5. When the inner-periphery-material exposed part 6 is resin-molded, an inner metal mold in which a position corresponding to a corner part at an inner periphery part protrudes is used; the corner part is brought into contact with the inner metal mold; a flat part keeps a gap between it and the inner periphery material 1 at a prescribed length; after that, the inner metal mold is coupled to an outer metal mold; a resin is injected and hardened. Accordingly, it is possible to resist a thermal stress by a difference in a coefficient of thermal expansion between the inner periphery material 1 and the resin-molded layer 5 at an overload during an operation of a transformer. Thereby, it is possible to prevent an exfoliation from being caused at an interface between the inner periphery material 1 and the resin-molded layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a resin molded coil for a molded transformer.

BACKGROUND OF THE INVENTION Conventional resin molded coils have several layers of glass fiber reinforced epoxy resin arranged around the inner circumference of the coil, with most of the inner circumference exposed, and the rest of the coil entirely molded with resin. The structure of the conventional molded coil thus obtained will be explained with reference to FIG. Reference numeral 8 denotes a glass fiber reinforced epoxy resin layer provided on the inner periphery of the coil. - For boat fishing, an amine-curing prepreg type material is used, and its curing is completed at the same time as the mold resin. Further, the resin content of the glass fiber reinforced epoxy resin is 40 to 50% by weight. 9 is an interlayer insulation material, which includes polyester film, polycarbonate film, polyphenylene sulfide film,
Kraft paper, polyester nonwoven fabric, etc. are used. 10
is a conductor, and in Fig. 2, it is a foil conductor, and aluminum foil (strip) or copper foil (strip) is used. Reference numeral 11 denotes a peripheral insulating material, which is made by winding several layers of interlayer insulating material, or is made of glass cloth, polyester nonwoven fabric, Nomex, glass fiber reinforced epoxy resin, or the like. 12 is a resin mold layer, and +3 is a terminal.

Problems to be Solved by the Invention In the conventional molded coil as described above, during practical use, especially due to temperature rise during overload, peeling occurs on the circumferential surfaces of the glass fiber reinforced epoxy resin layer 8 and the resin molded layer 12, resulting in electrical failure. This may cause insulation failure and damage to the transformer. This tendency is especially noticeable in areas other than corner areas.

Means for Solving the Problems In order to achieve the above object, the present invention involves winding a rectangular winding frame made of glass fiber reinforced epoxy resin to form a coil body, integrally molding the winding frame, and An exposed portion is provided at the inner corner portion, and a resin molded coil is constructed by integrating the coil with a molded resin layer that covers the entire area other than the exposed portion.

Function As mentioned above, only the corners of the rectangular inner peripheral material of the molded coil are exposed, and the other parts are molded, so the inner peripheral material and the resin molded layer will be damaged during overload during transformer operation. It can withstand thermal stress caused by a difference in coefficient of thermal expansion, and no peeling occurs at the interface between the inner peripheral material and the resin mold layer.

EXAMPLE An example of the present invention will be described below with reference to FIG.

Reference numeral 1 denotes an inner peripheral material of glass fiber reinforced epoxy resin, which forms a rectangular winding frame and contains 40 to 50% by weight of prepreg-like epoxy resin.

2 is an interlayer insulation material, which can be polyester film, polyester film, or polyester film depending on the heat resistance and insulation performance required by the coil.
The material is selected from among polyphenylene sulfide film, kraft paper, polyester nonwoven fabric, aromatic polyamide nonwoven fabric, and the like. 3 is a foil-like conductor, and the specific conductor material used is aluminum or copper. Further, the conductor is not limited to a foil-like conductor, and a magnet wire coated with an insulating film may be used as the conductor, but in this case, the interlayer insulating material 2 is not required. Reference numeral 4 is an outer peripheral insulating layer, which is formed by winding several layers of interlayer insulating material 2, or is made of glass cloth, polyester nonwoven fabric, Nomex, glass fiber reinforced epoxy resin, or the like. Reference numeral 5 denotes a molded resin layer, which covers the entire coil body formed by winding a wire around a rectangular winding frame. This mold resin layer uses an epoxy resin as a main ingredient and an acid anhydride such as methyltetrahydrophthalic anhydride (MeTIIPA), methylhexahydrophthalic anhydride (MetllPA), or hexahydrophthalic anhydride (uopA) as a curing agent.
Further, tertiary amine such as DMP-30 is used as a reaction accelerator, 0.2 to 0.5 PNP is mixed therein, and silica powder or the like is mixed in 50 to 60 PHR as a filler.

The resin mold layer is exclusively vacuum cast when the coil is used under high pressure, and is molded by normal pressure injection when used under low voltage. Reference numeral 6 denotes an exposed portion of the inner peripheral material, in which a corner portion of the glass fiber reinforced epoxy resin inner peripheral material 1 is exposed without being covered with the mold resin 5. When this inner peripheral material exposed portion 6 is molded with resin, an inner mold with protruding positions corresponding to the corner portions of the inner peripheral portion is used, and the corner portions and the inner mold are in contact with each other, and the rounded portions are formed in the inner mold. The gap with the surrounding material is maintained at about 2 to 3 m/m, and then it is combined with the outer mold and resin is injected and hardened. 7 is a terminal.

In the above embodiment, a prepreg-like epoxy resin with good workability is used as the glass fiber-reinforced epoxy resin inner peripheral material, but the material is not limited thereto. Moreover, the resin content is also 40~
Although the content is set at 50% by weight, the content is not limited to this and can be determined as appropriate in consideration of the influence on electrical insulation performance and mechanical properties.

Effects of the Invention As described above, the molded coil according to the present invention has an i
Since a reinforcing resin layer is formed on the V flat part, a transformer equipped with such a molded coil can withstand thermal stress caused by differences in thermal expansion coefficients, even if the coil temperature rises due to overload operation. Since peeling does not occur at the interface between the inner peripheral material and the mold resin, insulation reliability is increased.

Furthermore, since the exposed portions are formed at the corner portions of the inner peripheral material, the amount of molding resin used can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway schematic perspective view of a resin molded coil according to the present invention, and FIG. 2 is a partially cutaway schematic perspective view showing another embodiment. l...Epoxy resin inner circumference 3...Foil conductor 5.
...Mold resin 6...Inner peripheral material exposed part

Claims (1)

[Claims] (1) A coil body is formed by winding a rectangular winding frame made of glass fiber reinforced epoxy resin, and the coil body is integrally molded.
A resin molded coil characterized in that an exposed portion is provided at an inner corner portion of the winding frame and is integrated with a molded resin layer that covers the entire area other than the exposed portion.