JPH02214103A - Molded coil and manufacture thereof - Google Patents

Abstract

PURPOSE:To efficiently obtain a molded coil in which a crack is hard to cause, whose resin layer is thin and which is lightweight by a method wherein a rectangular-parallelepiped-shaped pressboard whose density and inorganic fiber content have been specified is filled into a synthetic resin with which a periphery of a raw coil has been covered. CONSTITUTION:A sheet winding 2 is formed on an FPP bobbin 1 in order to prevent an end part of a sheetlike insulator from being fixed in a state that the end part directly penetrates into an inner-periphery resin layer 3. When pressboards 5 whose cross-sectional area is rectangular, whose thickness is definite, whose density is 0.5 to 1.8g/cm<2> and whose inorganic fiber content is 50wt.% or higher are filled into synthetic resin layers 3, 4; thereby, a casting resin is impregnated completely. Thereby, it is possible to obtain a molded coil in which a crack is hard to cause, whose resin thickness is comparatively thin and uniform, in which an interface does not exist, whose insulation strength is excellent and which is lightweight.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a molded coil for a molded power distribution transformer and a method for manufacturing the same.

2. Description of the Related Art Conventional molded coils are made by connecting a sheet conductor and one or more windings made by winding a sheet insulator wider than the width of the conductor. It is formed by being coated with a layer of cured resin.

The conventional method for manufacturing molded coils as described above is to first form a winding (coil) using a sheet-like conductor and a sheet-like insulator that is wider than the sheet-like conductor without a winding core, and then this winding is Connect one or more of them to form an elementary coil. After that, this raw coil is set in a casting mold consisting of a casting guard and an outer frame consisting of a bottom plate, side plates, terminal board, etc., and after preheating the mold and the raw coil, the epoxy resin compound etc. A synthetic resin was injected and cured to form a cured resin layer around the elementary coil.

Problems to be Solved by the Invention The synthetic resin layer of the molded coil has electrical insulation, heat dissipation medium,
It plays a role as a structural material for coils, but in rare cases where cracks occur in the solidified synthetic resin layer, it can cause a significant drop in insulation performance, so there is a need to improve the coil structure and resin so that they are less prone to cracking. . However, in conventional molded coils using sheet windings, the sheet insulator used to insulate between turns of the windings is wider than the conductor width.
The end of the insulator was fixed directly into the synthetic resin layer. Therefore, the ends of these sheet-like insulators exhibit an effect similar to that of a wedge driven into the resin layer, causing cracks in the inner peripheral resin layer. Furthermore, the ends of these sheet-like insulators form a kind of interface with the molding resin, which causes a decrease in insulation strength, and has a particularly large effect on the decrease in impulse strength.

Furthermore, if the sheet-like conductor is thin, deformation of the bare coil is likely to occur when the bare coil is removed from the winding core and set in a casting mold. This was difficult and resulted in a decrease in insulation strength. In order to solve this problem, methods such as attaching a cone-shaped cured resin between the bare coil and the mold have been used, but the occurrence of an interface cannot be avoided.
This also caused an increase in manufacturing man-hours.

An object of the present invention is to efficiently produce a molded coil that is less prone to cracking, has a thin resin layer, and is lightweight.

Means for Solving the Problems In order to achieve the above object, the molded coil according to the present invention is attached to an FRP bobbin made by impregnating and adhering a thermosetting resin to a base material such as glass cloth or glass tape and hardening the bobbin. An elemental coil is formed by penetrating one or more sheet windings formed by winding a sheet-like conductor and a sheet-like insulator on top, and a synthetic resin layer coated around this elemental coil has a density 0.5 g/cni' ~ 1,8 g/c
ry? , is made by embedding a rectangular parallelepiped press board with an inorganic fiber content of 50% by weight or more, and its manufacturing method is to impregnate and adhere a thermosetting resin to a base material such as glass cloth or glass tape and then harden it on an FRP bobbin. A sheet-like conductor and a sheet-like insulator are wound around the coil to form one or more sheet windings to form an elementary coil, and the elementary coil is set in a casting mold, and the mold and moeki The cross-sectional area between the coils is rectangular, and the density is 0.5 g/crn'~l, 8 g/c.
rd, a press board with an inorganic fiber content of 501n% or more is interposed, and a synthetic resin is injected and cured under conditions where the distance between the mold and the bare coil is maintained.

ing.

By forming the sheet winding on the FRP bobbin, it is possible to prevent the ends of the sheet-shaped insulator from being fixed directly into the inner peripheral resin layer, thereby improving crack resistance and impulse strength. It is possible to prevent a decrease in In addition, the synthetic resin layer has a rectangular cross-sectional area, a constant thickness, and a density of 0.5 g/cni' to 1.8 g.
/crrI', by embedding a press board with an inorganic fiber content of 50% by weight or more, the resin for casting is completely impregnated, it is possible to form a synthetic resin layer without an interface, and the thickness of the resin layer is made uniform. The reliability of insulation can be improved.

Further, by forming the sheet winding on the FRP bobbin, deformation of the elementary coil can be minimized, and a synthetic resin layer without an interface can be easily formed using the press board.

EXAMPLE Hereinafter, the structure of a molded coil according to the present invention will be explained with reference to the drawings. FIG. 1 is an external perspective view of a molded coil according to the present invention, FIG. 2 is a cross-sectional view taken along line A-A, and FIG. 3 is a cross-sectional view taken along a plane including the first winding from the top of the molded coil.
Figures 5 and 6 show the parts.

1 is an FRP bobbin, which is made by impregnating and adhering a thermosetting resin to a base material such as glass cloth or glass tape and hardening it (
Figure 4). A sheet winding 2 is formed by winding a sheet conductor and a sheet insulator. This sheet winding 2
A plurality of coils are formed through the FRP bobbin 1 to form an elementary coil (FIG. 5). Reference numeral 3.4 denotes resin layers on the inner and outer peripheries of the sheet winding 2, which cover the sheet winding with a synthetic resin such as an epoxy resin compound molded with resin.

5 is a press board in which a plurality of pieces are embedded in the resin layer 3.4, and the density is 0.5 g/crr+'~I, 8 g/crr
l', a rectangular parallelepiped with an inorganic fiber content of 50% by weight or more is cut into dimensions according to the placement position, placed in a position where the elementary coil is easily deformed in the resin layer 3.4, and resin molded. ing.

Next, a method for manufacturing the resin molded coil will be described.

FIG. 6 is a perspective view showing the center of a casting mold used in the method of the present invention, and FIG. 7 is a perspective view of a state in which a raw coil and a press board are set in the mold.

An elementary coil formed by forming a sheet winding 2 on an FRP bobbin 1 is set in a casting guard 6 shown in FIG. At this time, for example, place a lommXl 0mmX 20m on the bottom plate for pouring.
Several press boards 5 of size m are placed, and the ends of the FRP bobbin 1 of the bare coil are placed on these press boards 5 to adjust the resin thickness of the ends. After setting the remaining mold parts such as the outer frame 7 for casting, for example, 1.6mm x 10mm x 300mm
Press board cut to mm size and cast with 6 and FR
By sandwiching a plurality of coils between the P bobbins 1 and between the outermost periphery of the sheet winding 2 and the casting outer frame 7, the distance between the coils and the mold can be kept constant (FIG. 7).

Next, preheat the mold and the coil at 80°C for 4 hours,
After drying, the epoxy resin compound is cast and cured to obtain a molded coil with excellent insulation properties.

Effects of the Invention Since the present invention employs the manufacturing method described above, it is easy to maintain a constant distance between the mold and the raw coil when the raw coil is set in the mold using the bobbin and the press board, and the sheet-shaped coil can be easily maintained. Work efficiency can be easily increased without deforming the conductor. In addition, the resin molded coil obtained by the method of the present invention has advantages such as being free from cracks, having a relatively thin resin thickness and uniformity, having no interface, excellent insulation strength, and being lightweight.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view of a molded coil according to the present invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, Fig. 3 is a sectional view of the main part of Fig. 1, and Fig. 4 is a perspective view of the molded coil used in the method of the present invention. FIG. 5 is a side view of the bare coil, FIG. 6 is a perspective view showing the center of the casting mold, and FIG. FIG. 3 is a perspective view of a state in which an elementary coil and a press board are set in a mold. l...FRP bobbin 2... Sheet winding 3...
Inner peripheral resin layer 4... Outer peripheral resin layer 5... Press board 6... Casting precautions 7''... Outer frame for casting Figure 3 Figure 4 Figure 1: FR, P bobbin

Claims (2)

[Claims] (1) One or more FRP bobbins formed by impregnating and adhering a thermosetting resin to a base material such as glass cloth or glass tape and hardening the bobbin, and winding a sheet-like conductor and a sheet-like insulator on the bobbin. A raw coil is formed by penetrating a plurality of sheet windings, and a synthetic resin layer coated around this raw coil has a density of 0.5 g/cm^3 to 1.8 g/cm^3.
A molded coil comprising a rectangular parallelepiped press board having an inorganic fiber content of 50% by weight or more. (2) One or more sheet windings are created by winding a sheet-like conductor and a sheet-like insulator on an FRP bobbin that is cured by impregnating and adhering a thermosetting resin to a base material such as glass cloth or glass tape. is formed into an elementary coil, and the elementary coil is set in a casting mold, and the cross-sectional area between the mold and the elementary coil is rectangular, and the density is 0.5 g/cm^3 to 1.
8 g/cm^3, a press board with an inorganic fiber content of 50% by weight or more is interposed, and a synthetic resin is injected and cured under conditions that maintain the distance between the mold and the bare coil. manufacturing method.