JPS58162016A - Small sized tranformer - Google Patents

Abstract

PURPOSE:To make easy automatic assembling and make less eddy current by inserting a core into the center hole of a bobbin providing the primary and secondary coil and by winding the magnetic belt material at the circumference of the bobbin so that the both end surfaces of core are opposed. CONSTITUTION:An internal magnetic core 3 is inserted into the center hole of bobbin 2 providing the primary and secondary coil 1. The internal magnetic core 3 can be formed by laminating belt type ribbons such as permalloy or silicon steel plate and then baking it into a squarepillared shape. Both end surfaces of it are alined by the polishing and are extruded a little from the bobbin 2. Both external side surfaces of bobbin 2 are integrated with the winding guide frames 4, 4. The belt type ribbon 5 consisting of the same material as the internal magnetic core 3 is wound around the circumference of the bobbin 2 for the predetermined number of turns with said guide frame used as the guide. This belt type ribbon 5 becomes the external magnetic core and forms a closed magnetic circuit in cooperation with the internal magnetic core 3. Since the intenal magnetic core 3 is extruded a little from the bobbin 2, the belt type ribbon 5 is firmly wound to the internal magnetic core 3, not generating any gap at the contact area.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compact power transformer connected to various electronic circuits for voltage transformation.

In the conventional small transformer of this type, the iron core is It
,, It was made by combining I-shaped or L-shaped punched plates, butting them together, and then layering them. However, with this structure, assembly of the iron core is troublesome and requires automatic assembly, and a lot of material is wasted when punching out the core. Furthermore, even if rolled sheet metals, which are generally used as materials, have excellent magnetic properties in the rolling direction, their magnetic properties deteriorate significantly in the direction perpendicular to the rolling direction. For this reason, Kl type or L type
In iron cores of all shapes and sizes, there is always a part with inferior magnetic properties in the magnetic circuit, and this leads to a decrease in efficiency.

The present invention aims to eliminate the drawbacks of the above-mentioned prior art, and one embodiment thereof will be described below.

In FIGS. 1 and 2, an inner magnetic core 3 passes through the center hole of a bobbin 2 around which primary and secondary coils are wound. The inner magnetic core 3 of this embodiment is made by laminating strip-shaped ribbons such as permalloy or silicon plates and firing them into a prismatic shape. Both end surfaces thereof are uniformly rubbed by polishing or the like, and protrude slightly from the bobbin 2. bobi 42
Winding guide frames 4, 4 are integrally protruded from the inner and outer sides of the bobbin 2, and using the winding guide frames 4, 4 as a guide, a strip ribbon 5 made of the same material as the inner magnetic core 3 is wound around the outer periphery of the bobbin 2 for a predetermined number of turns. The strip ribbon 5 serves as an outer magnetic core and cooperates with the inner magnetic core 3 to form a closed magnetic circuit. The belt-shaped ribbon 5 of the outer magnetic iron core can be obtained by partially modifying a well-known automatic winding machine (not shown) used when winding the coil 1.
It can be wrapped around. Inner magnetic core 3 is slightly 'j' from bobbin 2! Since the belt-like ribbon 5 is extended, the inner magnetic core 3 is strongly supported, and this junction partial pressure gap does not occur. Note that the structure of the inner magnetic core 3 is not in the above embodiment.

According to the small transformer with this configuration, automatic assembly can be easily applied, and the material can be #'! There is almost no waste and therefore it can be manufactured at low cost. Furthermore, the easy magnetization axes of the inner magnetic core and the outer magnetic core are completely separated from the magnetic path, and the eddy current loss can be reduced compared to the conventional laminated plate structure, resulting in better characteristics. In addition, since the inner magnetic core is expelled from the bobbin and a ribbon is wrapped around it, the effect of MK is remarkable, such as no gap occurring at the joint between the inner magnetic core and the outer magnetic core.

[Brief explanation of the drawing]

The drawings relate to an embodiment of a small transformer according to the present invention.
41 is a partially sectional front view thereof, and FIG. 2 is a sectional view taken along the line T' in FIG. 1. 1... Carp 2... Bobbin 3, e, inner magnetic core 4... Winding guide frame 5...@Magnetic strip material (outer magnetic core) 1 Applicant Seikosha Co., Ltd. Daiichi □ □ 74- 5-5 1 2 1 ■ ~5

Claims (1)

[Claims] 1. Insert the iron core into the center hole of the bobbin around which the primary and secondary coils have been wound, and place a magnetic strip around the outer periphery of the bobbin once so that both end surfaces of the iron core face each other. A small transformer. 2. The small transformer according to claim 1, wherein the bobbin is integrally provided with a winding guide frame for the strip material on its inner and outer surfaces. 3. The small transformer according to claim 1, wherein the iron core slightly protrudes from the bobbin.