JP2757764B2 - Mold transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold transformer used for various video equipment, home appliances, communication equipment and the like.

[0002]

2. Description of the Related Art A conventional mold transformer will be described below.

FIG . 3 is a sectional view showing the internal structure of a conventional mold transformer. FIG. 4 is a perspective view of a conventional mold transformer.

A through-hole 2 is provided at the center, and flanges 8 are provided at both ends. A maker terminal 5 for winding wiring which is inserted into the lower end flange 4 of the flange 8 so as to be integrated with each other, and a user terminal used by a user Coil bobbin 1 provided with 6
Then, a transformer body in which a closed magnetic circuit is formed by winding a lead wire 3 such as a copper wire, winding a lead wire of the lead wire 3 around the maker terminal 5 and inserting the EE type or EI type ferrite core 7 in combination therewith is inserted. In this case, only the user terminals 6 are exposed and the exterior 9 is formed by molding with a molding resin.

[0005]

In such a conventional molded transformer, since the entire transformer body is molded with resin, an EE-type or EI-type ferrite core 7 which is a magnetic material used for the transformer is used. , A molding stress was applied, and a marked decrease in inductance occurred.

FIG. 5 is a perspective view of an EE type ferrite core 7 used in a transformer. When the transformer body is molded with a thermoplastic resin, the shrinkage of the resin causes the ferrite core used in the transformer to shrink. 7, a force due to resin molding shrinkage is applied to the common magnetic leg portion of the E-type core, the outer peripheral portion 7a of the I-type core, the outer peripheral portions 7b of both outer magnetic legs, the upper surface 7c of the ferrite core 7, and the like. Damage or application of stress to the ferrite core 7 causes magnetostriction to reduce the magnetic permeability, resulting in a reduction in inductance.

An object of the present invention is to improve the above-mentioned conventional problems, and an object of the present invention is to provide a molded transformer which reduces a decrease in inductance.

[0008]

In order to achieve this object, a molded transformer according to the present invention comprises a closed magnetic circuit by incorporating an EE type ferrite core into a coil bobbin in which a through hole is provided at the center and a conductive wire is wound around the outer periphery. And the transformer itself,
The entire body of the transformer body is formed by molding with a thermoplastic resin so as to expose a terminal portion used by a user of the transformer body, and a part of an outer peripheral portion of the ferrite core is exposed from the exterior, and is exposed from the exterior. Ferrite
In this configuration, a part of the outer magnetic legs is only the outer peripheral portions of both outer magnetic legs .

[0009]

When the transformer body is molded using a thermoplastic resin as described above, an EE type ferrite core is used.
While exposing a part of this ferrite core.
Part of the ferrite core exposed from the exterior.
Since only the outer peripheral portion of the outer magnetic leg is provided, molding stress due to molding shrinkage of the resin can be eliminated. Accordingly, since no stress is applied to the ferrite core, a reduction in magnetic permeability due to magnetostriction can be prevented, and a molded transformer with less characteristic deterioration such as a reduction in inductance can be manufactured.

Further, since only a part of the ferrite core is exposed, the ferrite core can be fixed with resin.

[0011]

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a mold transformer according to a first embodiment of the present invention. FIG. 2 shows a perspective view thereof. A through hole 22 is provided at the center,
A coil bobbin 21 is formed by implanting a wound wiring maker terminal 25 and a user terminal 26 used by a user, which are integrally formed by insert molding.

A conductor 2 such as a copper wire is connected to the coil bobbin 21.
The EE- type ferrite core 27 is inserted into the coil bobbin 21 around which the lead-out portions are wound around the maker terminal 25 and wired to form a closed magnetic circuit. This transformer main body is molded with a thermoplastic resin such as a liquid crystal polymer so as to expose the user terminals 26 to form an exterior 29.

At this time, only the outer peripheral portions 27b of both outer magnetic legs of the E-shaped core of the ferrite core 27 are exposed. This is an effective method for securing a withstand voltage between the user terminal 26 and the ferrite core 27. Therefore, it is possible to supply a molded transformer that does not cause a decrease in inductance due to a decrease in magnetic permeability due to cracks in the ferrite core or magnetostriction in the ferrite core and that ensures a high withstand voltage between the user terminal 26 and the ferrite core 27.

[0015]

As described above, the present invention eliminates stress due to molding shrinkage that occurs when molding a ferrite core type transformer body, eliminates cracks in the ferrite core, and reduces the magnetic permeability from the occurrence of magnetostriction in the ferrite core. Thus, it is possible to realize a molded transformer that does not have characteristic deterioration such as lowering of inductance due to lowering.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold transformer according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a mold transformer according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional mold transformer.

FIG. 4 is a perspective view of a conventional mold transformer.

FIG. 5 is a perspective view of the ferrite core.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Coil bobbin 22 Through-hole 23 Conductor 24 Lower end flange 25 Manufacturer terminal 26 User terminal 27 Ferrite core 28 Flange 29 Exterior

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-152144 (JP, A) JP-A-1-175710 (JP, A) JP-A-4-105523 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) H01F 27/32 H01F 27/26

Claims (1)

(57) [Claims] An EE- type ferrite core is incorporated into a coil bobbin having a through hole provided in the center and a conductor wound around the periphery to form a closed magnetic circuit to form a transformer body, and a terminal portion of the transformer body used by a user is exposed. the whole to form the exterior by molding a thermoplastic resin, Available from the exterior to expose the outer peripheral portion of the portion of the ferrite core
Part of the ferrite core exposed from the exterior
Mold transformer with only the outer periphery of the legs .