JPH0447967B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface-shielded molded transformer that is safe even if a human body touches the surface of the molded coil during energization, and particularly to a terminal structure for grounding the shield layer of the molded coil.

The surface of the molded coil is covered with an insulating resin layer, but because of the capacitance that exists between the resin layer and the ground, generally when a molded transformer is energized, the surface of the molded coil will have a considerable high voltage. It has a potential and there is a risk of electric shock if the body touches it. As a countermeasure, a shield layer made of a sprayed metal coating of aluminum, zinc, etc., which has good adhesion to the resin layer and is chemically stable, is provided on the surface of the resin layer except for the area around the terminals of the molded coil. It was previously proposed to ground the
−179670).

Figures 1 to 3 are diagrams showing this surface shield type molded transformer, where 1 is an iron core, 2 is a molded coil combined with this, 3 is a coil conductor, 4 is an insulating resin layer, and 5 and 6 are coils. Terminals, 7 are a shield layer made of a metal spray coating coated on the surface of the insulating resin layer 4 except for the periphery of these terminals, 8 is a grounding terminal fitting, and 9 is a grounding wire connected to this, The other end of the wire 9 is a core fastener 10 at ground potential.
etc., and ground the shield layer 7.

In such surface-shielded molded transformers, the second method for grounding the shield layer is
A method of connecting a grounding wire 9 to a terminal fitting 8 soldered to a shield layer 7 as shown in FIGS.
Alternatively, a method of directly soldering the ground wire 9 to the shield layer 7 is usually considered. However, with these methods, the metal spray coating that forms the shield layer is
Since it is extremely thin at ~200 μm, there is a risk that the shield layer will peel off when external force is applied to the grounding wire, making it unsuitable for surface-shielded molded transformers that require grounding reliability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a surface-shielded molded transformer that improves the reliability of grounding of the shield layer and ensures safety.

In order to achieve the above object, the present invention provides a molded transformer having a shield layer formed on the surface of an insulating resin layer and a ground wire terminal for grounding the shield layer, and a terminal for connecting the ground wire terminal. One end of the metal fitting is embedded in the insulating resin layer, and the other end of the terminal metal fitting has a first surface that adheres to the shield layer and a second surface that protrudes from the first surface with a step. and the ground wire terminal is fastened and connected to the second surface so as to press the shield layer through a washer.

Embodiments of the present invention will be described below with reference to FIGS. 4 to 9.

As shown in FIGS. 4 and 5, when making a molded coil 2 by covering a coil conductor 3 with an insulating resin layer 4 by casting, a terminal seat 11, which is a part of the grounding terminal fitting, is pre-plated with metal. It is set in a mold, resin is injected around it, cured, and embedded and fixed in the insulating resin layer 4. The best place to embed the terminal seat 11 is near the coil terminals 5 and 6, which have thick resin layers, and at the bottom of the coil where the ground wire can be easily connected.

As shown in FIG. 8, the terminal seat 11 has a portion embedded in the resin layer 4 and a portion exposed from the surface of the resin layer 4. The portion exposed from the surface has a step, and the first surface 11a and It consists of a second surface 11b.

Next, as shown in FIGS. 6 and 7, a metal such as aluminum or zinc is thermally sprayed onto the surface of the molded coil 2, except around the coil terminals 5 and 6, to form a shield layer with a thickness of about 20 to 200 μm. form 7.
At this time, the first surface 11a of the terminal seat 11 exposed from the insulating resin layer 4 is also coated with a metal spray coating to connect the terminal seat 11 and the shield layer 7. As shown in FIG.
connected to. The second surface 11b exposed from the resin layer 4 of the terminal seat 11 is flush with the resin layer 4 except for the central protrusion 14 where the screw hole 13 is provided, and a metal spray coating is applied to this portion and the surface of the resin layer 4. A shielding layer 7 is applied. The surface of the portion of the terminal seat 11 to be embedded in the resin layer is roughened by shot blasting to improve adhesion to the resin layer, and the same treatment is applied to the portion to which the shield layer 7 is attached. It's good to keep it.

As shown in detail in FIG. 8, it is most desirable for the terminal seat 11 to have a circular cross section in terms of cost and to prevent stress concentration in the resin layer 4. It is sufficient if the shape is such that stress does not concentrate on it.

FIG. 9 shows the connection state of the ground wire. The ground wire terminal 16 has a tightening bolt 1 screwed into the screw hole 13.
2 and spring washer 15 to secure the terminal seat 11.
However, since the metal spray coating forming the shield layer 7 is very thin at 20 to 200 μm and does not have sufficient strength, the shield layer 7 is fixed to the first surface 11a of the terminal seat 11. By interposing a washer 18 that is slightly thicker than the height of the protrusion 14 of the terminal seat between the ground wire terminal 16 and the ground wire terminal 16, and tightening it so as to press down the shield layer, damage to the shield layer 7 can be prevented and the grounding can be improved. Reliability can be improved.
As the grounding wire 9, it is desirable to use a highly flexible braided wire in order to avoid applying excessive force to the molded coil. The other terminal 17 of the ground wire is fixed to a ground terminal provided on the core fastener 10, as shown in FIG. 1, and the shield layer 7 is grounded.

As explained above, according to the present invention, one end of the terminal fitting for connecting the ground wire terminal is embedded in the insulating resin layer, and the other end of the terminal fitting is connected to the first surface attached to the shield layer. The protruding portion that protrudes from the surface with a step has a second surface, and the grounding wire terminal is fastened and connected to the second surface by crimping the shield layer via a washer, so that the grounding wire terminal can be used for grounding. The terminal fitting is firmly fixed to the molded coil, and even if an external force is applied to the grounding wire, the shielding layer will not peel off and the grounding can be established reliably, so a highly safe surface-shielded molded transformer can be obtained.

[Brief explanation of the drawing]

Figures 1a and b are front and side views of a surface-shielded molded transformer, Figure 2 is a perspective view of a shielded molded coil according to the prior art, Figure 3 is its A-A' cross-sectional view, and Figure 4. is a perspective view of the molded coil according to the present invention before thermal spraying, and FIG.
B′ sectional view, FIG. 6 is a perspective view of the molded coil according to the present invention after thermal spraying, FIG. 7 is a C-C′ sectional view thereof, FIG. 8 is a detailed view of the ground terminal portion, and a is a sectional view. , b is a side view, and FIG. 9 is a sectional view showing the connection state of the ground wire. 1: Iron core, 2: Molded coil, 3: Coil conductor, 4: Insulating resin layer, 5, 6: Coil terminal, 7:
Shield layer, 9: Grounding wire, 11: Terminal seat which is part of the grounding terminal fitting, 11a: First surface, 11b:
Second surface, 12: Ground wire terminal tightening bolt, 16,
17: Ground wire terminal, 18: Washer.

Claims (1)

[Scope of Claims] 1. In a molded transformer having a shield layer formed on the surface of an insulating resin layer and a grounding wire terminal for grounding the shielding layer, one end of a terminal fitting connecting the grounding wire terminal is connected to the grounding wire terminal. embedded in an insulating resin layer, the other end of the terminal fitting has a first surface that adheres to the shield layer and a second surface that is a protruding portion that projects from the first surface with a step difference; A surface shield type molded transformer, characterized in that the grounding wire terminal is fastened and connected to two surfaces through a washer so as to press the shield layer.