JPH059928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a core assembly for a leaky transformer used in a ballast for a discharge lamp or the like.

Conventionally, a primary coil and a secondary coil are wound around a bobbin or core so that the coil axes coincide, and a plate-shaped or rod-shaped core called a pass core or shunt core is placed between the primary coil and the secondary coil. A leaky transformer is known. However, the conventional core for this type of transformer is of a type in which silicon steel plates are laminated, which is difficult to manufacture, and the overall shape is relatively large, resulting in large iron loss. Particularly when used at high frequencies, the influence of iron loss is large, resulting in a reduction in efficiency.

In order to solve this problem, a transformer core assembly as shown in FIG. 1 has been proposed, which is entirely composed of a ferrite core. To briefly explain this configuration, E
The shaped ferrite core 1 has square outer legs 3 and 4 connected to both ends of a rectangular back column wall 2, and a cylindrical center leg 5 having approximately the same length as the outer legs 3 and 4 in the center of the back column wall 2. is formed. The hollow ferrite core or ring core 6 is a cylindrical core having a through hole 7 in the center. 2 E-type ferrite cores 1,
1' are combined into a Japanese character shape as a whole with their legs 3 and 3', 4 and 4', and 5 and 5' facing each other, and a ring core 6 is inserted near the tips of the central legs 5 and 5'. As shown in FIG. 2, primary coils 8 and 2 coils 9 are wound around each central leg 5 and 5', respectively, thereby forming a leakage transformer.

In order to construct the E-type ferrite core 1 as shown in FIG. 1 by molding, the core 1 as shown in FIG.
The material is placed horizontally and pressurized in the vertical direction by upper molds 10, 10'10'' and lower molds 11, 11'11'' to form each part. In this case, since the central leg 5 has a completely circular cross section, there is a risk that the tips 10a, 11a of the upper and lower molds 10', 11' of the central leg portion will interfere with each other when molding is completed, damaging the mold. However, there was a problem in that a dimensional error occurred in the cylindrical central leg 5.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a core assembly for a leaky transformer which eliminates the above-mentioned disadvantages and which is capable of holding a ring core attached to a central leg in a predetermined position.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a side view of the E-type ferrite core 1 according to the present invention as seen from the leg side, and FIG. 5 is a ring core 6 attached to the center leg 5 of the E-type ferrite core 1.
FIG. The plate-shaped outer legs 3 and 4 are connected to both ends of the plate-shaped back column wall 2, which is the same as the conventional example explained in FIG. 1, but in the embodiment shown in FIG. It is a cross section of a small coin. That is, both side portions facing the outer legs 3 and 4 are formed into flat surfaces 5a and 5b parallel to the plate surfaces of the outer legs.
The ring core 6 is also formed with a through hole 7 having a pair of flat surfaces 7a and 7b corresponding to the central leg 5, as shown in FIG. Fig. 6 shows a core assembly in which E-type ferrite cores 1 and 1' as shown in Fig. 4 are combined in a Japanese letter shape, and a ring core 6 as shown in Fig. 5 is installed between the central legs 5 and 5'. FIG. Flat surface 5a or 5b of central leg 5 or 5' and flat surface 7a, 7b of hole 7 of ring core 6
The ring core 6 does not rotate relative to the center leg due to the contact between the two parts, thereby preventing the ring core 6 from being misaligned.

FIG. 7 is a sectional view showing a mold for molding the E-type ferrite core 1 according to the present invention. In this case, since the central leg 5 has flat surfaces 5a and 5b, the tips 10b and 11b of the upper and lower molds do not interfere with each other, improving the shape and dimensional accuracy of the molded product.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional transformer core assembly;
FIG. 2 is a plan view of a leaky transformer using the core assembly shown in FIG. 1, FIG. 3 is a schematic diagram showing the molded state of the core assembly shown in FIG. 1, and FIG. 4 is an embodiment of the present invention. A side view of the E-type ferrite core seen from the leg side,
FIG. 5 is an end view of a ring core applied to an embodiment of the present invention, FIG. 6 is a plan view of a transformer core assembly according to the present invention, and FIG. 7 is a mold for an E-type ferrite core according to the present invention. FIG. 2 is a cross-sectional view showing the device in operation. 1, 1'...E type ferrite core, 3, 4...
Outer leg, 5...Central leg, 6...Ring core, 5
a, 5b, 7a, 7b...Flat surface, 7...Through hole, 10, 10', 10''...Upper mold, 11, 11',
11″…lower mold.

Claims (1)

[Claims] 1. It has a pair of ferrite cores in which two lateral legs and a roughly cylindrical central leg are connected by a dorsal wall, and a ring core into which the central legs are inserted, and the legs of the pair of ferrite cores face each other. In the core assembly for a leaky transformer, the ring core is arranged in a Japanese character shape, and the ring core is attached almost near the tip of the center leg, wherein both ends of the center leg are formed into flat surfaces, and the inner peripheral part of the ring core is A core assembly for a leaky transformer, characterized in that a partial flat surface is formed to match the outer peripheral shape of the central leg.