JP3030104B2 - Insulation method of annular core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for insulating a circular core used in a common mode choke coil for preventing electromagnetic noise in an electronic device.

[0002]

2. Description of the Related Art A conventional method of insulating a circular core in the case where two windings are separated and wound around one circular core when a common mode choke coil is formed, as shown in FIG. And an annular core 3 which is usually a toroidal type core or a frame type core is housed in an insulating cover made of an insulating resin divided into a cover plate 2 and an insulating resin. The main body 1 is provided with an annular bottom between the double cylinders to form a core storage space, and a required length from both end surfaces of the inner cylinder for equally dividing the inner cylinder space into two portions parallel to the axial direction. A projecting central partition plate 4 is provided integrally with the inner cylinder,
Further, the protruding portion of the central partition plate 4 is connected to a pair of lower partition plates 5 which are wider than the central partition plate 4 provided integrally with the annular bottom in the radial direction and have the same height as the protruding portion. The lid plate 2 is an annular plate fitted into the opening of the double cylinder of the main body 1, and has a pair of upper partition bases 6 corresponding to the lower partition base 5 of the main body 1 on the surface thereof.
Are provided integrally. The insulating cover insulated the two windings wound through the divided space of the inner cylinder and the annular core 3, and the center partition 4, the lower partition plate 5, and the upper partition 6 insulated the windings.

[0003]

In the case of an insulating cover divided into a main body and a cover plate, there is a gap between the substrate and the main body in a space for accommodating the annular core and another extra space for accommodating the core.
In order to secure a required insulation distance between the winding and the annular core, it is necessary to increase the thickness of the substrate, and the depth of the main body also needs to be increased. Also, while the insulating cover can be made with a small dimensional tolerance, it is difficult to make the size of the annular core accurately and inexpensively, and the dimensional tolerance becomes large. For this reason, there is a disadvantage that the annular core may rattle in the insulating cover, and the insulating cover may be distorted by winding. An object of the present invention is to provide a method of insulating a circular core used for a common mode choke coil, which is provided with a resin mold in which a circular core is integrally formed of resin.

[0004]

SUMMARY OF THE INVENTION The present invention focuses on the fact that an insulating cover of an annular core used for a common mode choke coil is provided with a central partition plate and a partition base for insulating windings from each other. The annular core is supported by contacting the tips of two or more pins on the outer peripheral surface corresponding to the partition of the annular core, and the annular core is buried in resin by injection molding. The method is characterized in that an insulating cover is directly formed on the substrate.

[0005]

The pin supports the annular core at a place where the trace does not impair the required insulation distance between the winding and the annular core, and makes the thickness of the insulating cover with respect to the annular core uniform to assure insulation characteristics.

[0006]

FIG. 1 is a perspective view showing an external appearance of an embodiment of an insulating cover showing an insulating method of an annular core for a common mode choke coil according to the present invention. FIG. 2 is a cross-sectional view taken along line AA of FIG. As shown in FIGS. 1 and 2, the annular core 3 covered with the insulating cover 7 is provided in the injection molding die at a position facing the inner wall of the injection molding die (not shown). 2 is provided to be able to come and go freely to position the annular core
The annular core is positioned by four pins in total, the annular core is supported in a suspended state in a mold, and the annular core 3 is buried with resin by injection molding. Figure 1,
In FIG. 2, a small hole 8 on the outer peripheral surface of the insulating cover 7 is a mark where the above-mentioned pin has been removed. Therefore, the surface of the annular core 3 is closely covered with the insulating cover 7 except for the small holes 8. The small holes 8 are formed together with the insulating cover 7 and are located at positions corresponding to the central partition plate 9 on the inner peripheral portion and the partition tables 10 on the upper and lower surfaces. Two windings (not shown) of the choke coil are wound around the insulating cover 7 through the spaces on both sides of the center partition plate 9 respectively, and are not wound around the outer peripheral surface indicated by the arrow in FIG. Since the small hole 8 is located at the center of the portion where the winding does not exist, the insulation distance between the annular core 3 and the winding can be secured to a predetermined dimension or more. Because of the small holes 8, it is not necessary to increase the thickness of the outer peripheral portion, and the minimum thickness that can be formed can be achieved. The annular core of the present embodiment may be a soft magnetic ferrite core or an annular core made of a wound core made of an amorphous material.

[0007]

According to the method of insulating the annular core according to the present invention, the insulating cover can be made small and the required amount of resin can be reduced. Since the annular core does not rattle in the insulating cover, no abnormal noise is generated during use, and no distortion occurs in the insulating cover due to winding, so that the finish of the coil is uniform and good, This has the effect of stabilizing quality. Further, the annular core wrapped with the insulating cover is easy to handle, and thus has an effect of improving the efficiency of the winding operation and the like.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view showing an example of a conventional annular core insulating method in a state where the annular core is housed in an insulating cover.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Cover plate 3 Annular core 4, 9 Center partition plate 5 Lower partition plate 6 Upper partition plate 7 Insulation cover 8 Small hole 10 Partition table

Claims (1)

(57) [Claims] 1. An insulating cover made of a resin having electrical insulation characteristics, comprising: a ring-shaped core; a central partition plate for insulating windings from each other; and a partition table provided integrally with the central partition plate so as to protrude up and down. An annular core insulating method for covering an annular core, wherein the annular core is positioned with a pin in a molding die at a position on an outer peripheral surface connecting the upper and lower partitions, and molded so as to be embedded in the resin. A method of insulating a circular core.