JP3241194B2 - Resin mold coil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded coil which is advantageous in realizing reliability and cost reduction.

[0002]

2. Description of the Related Art Conventionally, a molded coil of a molded transformer manufactured by a mold method is such that after the coil is housed in a mold, a resin is filled around the coil in a vacuum. However, cracks are likely to occur in the resin due to the difference in thermal expansion coefficient between the coil conductor and the mold resin, and consideration has been required for this. As a method generally used as a measure against the crack, a method of increasing the resin thickness or using a reinforcing material has been adopted.

The prior art will be described below with reference to FIGS. FIG. 4 is a partial schematic cross-sectional view of a conventional molded coil. In the drawings, reference numeral 1 denotes a coil conductor, which is a round wire or sheet of aluminum or copper. Reference numeral 2 denotes a mold resin layer which is usually formed by mixing an appropriate amount of an inorganic filler. The most frequently used resin is an epoxy resin. Further, silica, alumina, and the like are often used as the inorganic filler. In the figure, the resin layer thicknesses t1 and t2 are also about 510 mm.

FIG. 5 shows a case where a reinforcing material is used. In the figure,
21 is a coil conductor and 22 is a molding resin, and the contents are the same as those described above. Reference numeral 23 denotes a reinforcing material for the mold resin 22, and specifically, glass cloth or plastic cloth is often used. Although the resin layer can be made thinner by reinforcing with the glass cloth or the like, the thermal behavior of the resin and the thermal behavior of the glass cloth reinforced resin are significantly different from each other.

[0005] Further, in the case where a small fiber is twisted into a cloth, it is difficult to sufficiently impregnate the cloth with the resin because the cloth contains many fine voids. Consideration must be given to partial discharge during application.

[0006]

As described above, the conventional molded coil has a large resin thickness, large size, heavy weight and high cost in consideration of crack resistance. . Further, in the configuration using the reinforcing material, there is anxiety about resin impregnation and anxiety about crack resistance due to a difference in thermal behavior with the mold resin.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a resin mold coil which is excellent in reliability and can be manufactured at low cost.

[0008]

In order to achieve the above-mentioned object, the present invention provides a method of forming a resin layer on the inner and outer circumferences of a coil by using inorganic paper having a fiber density of 0.12 to 0.25 g / cm ^3. When reinforcing and using a plurality of the reinforcing members, a resin spacer is provided between the layers.

[0009]

According to the configuration of the resin mold coil of the present invention, the resin reinforcing material has a fiber density of 0.12 to 0.2.
Since the inorganic paper of 5 g / cm ³ is used, the impregnating property of the resin is good, and the thermal behavior of the reinforced insulating layer is similar to that of the resin.
Abnormal stress generation is reduced.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a partially schematic sectional view of one embodiment of the present invention, and FIG. 1B is a partially cutaway sectional view of one embodiment of the present invention. In the figure, 31 is a coil conductor as a component,
Reference numeral 32 denotes a mold resin, and reference numerals 33 and 34 denote reinforcing members of the mold resin which are features of the present embodiment. The reinforcing material is glass paper or other ceramic paper having a low fiber orientation, and has a density of 0.12 to 0.25 g / cm ³ . As shown in FIG. 2, when the density of the inorganic fiber (glass) paper is smaller than the above-mentioned value as shown by the solid line in FIG.
Also, if the value is large, resin impregnation becomes difficult,
In addition, the thermal behavior greatly differs from that of the resin, and the reliability with respect to crack resistance is reduced. The dotted line in FIG. 2 indicates the dielectric strength.

FIG. 3 shows the results of measuring their thermal behavior. In the figure, denotes a case of a single mold resin, denotes a sample reinforced with glass paper according to the present embodiment, and denotes a case where resin reinforcement is performed with a conventional glass cloth reinforcing material.
From this, it can be understood that the reinforcing material according to the present embodiment is close to the thermal behavior of the resin, and the thermal stress due to the temperature rise due to the heat generated during the actual operation of the molded coil is reduced.

Further, in the material composition of the present embodiment having the above-described thermal behavior, the conductor has a thermal expansion coefficient of 23 × 1.
In 0 ^-6 / ° C. or higher, the average thermal expansion coefficient of the molding resin 45
Particularly excellent results are obtained when the temperature is not higher than × 10 ^-6 / ° C.

In FIG. 1, reference numeral 35 denotes a resin spacer, which is preferably of the same quality as the mold resin 32. The resin spacer 35 can be formed by dropping resin directly onto the reinforcing members 33 and 34 and curing the resin. 36 is a terminal. When the terminal 36 protrudes as shown in FIG. 1 (b), when the coil portion is reinforced with a reinforcing material, the thermal behavior of the terminal 36 with the resin is different, and cracks occur in the terminal 36. Consideration must be given to the method of reinforcing the coil body.

[0014]

As described above, according to the present invention, the mold resin layer can be made thinner, and the reliability against high voltage and the reliability against cracks are improved.

[Brief description of the drawings]

FIG. 1A is a schematic cross-sectional view of a part of a molded coil according to an embodiment of the present invention; FIG.

FIG. 2 is a characteristic diagram of inorganic fiber (glass) paper.

FIG. 3 is a graph showing an experimental result of a thermal behavior of a material.

FIG. 4 is a partial schematic cross-sectional view of a conventional resin mold coil.

FIG. 5 (a) is a partial schematic cross-sectional view of another conventional resin molded coil, and FIG. 5 (b) is a plan view of the same resin molded coil.

[Description of Signs] 31 Coil conductor 32 Mold resin 33, 34 Reinforcement 35 Resin spacer 36 Terminal

Claims (6)

(57) [Claims] 1. A resin molded coil wherein the inner and outer resin layers of the coil are reinforced with an inorganic fiber paper reinforcing material having a fiber density of 0.12 to 0.25 g / cm ³ . 2. A resin mold in which a terminal portion of the coil protrudes from another portion, wherein the resin layer on the inner periphery of the coil and at least the outer periphery other than the terminal portion of the coil are reinforced by the reinforcing material according to claim 1. coil. 3. The resin-molded coil according to claim 1, wherein a plurality of reinforcing members are used, and spacers are provided between the layers. 4. The resin molded coil according to claim 3, wherein the spacer is a resin spacer bonded to a part of the reinforcing member. 5. The resin mold coil according to claim 1, wherein the inorganic fiber paper is glass fiber. 6. The conductor has a coefficient of linear expansion of 23 × 10 ⁻⁶ / ° C. or more and the average coefficient of linear expansion of the mold resin is 45 × 10 ⁻⁶ / ° C.
Claims 1, 2, 3, 4, 5 characterized by the following.
The resin molded coil according to any one of the above.