JPS63311712A - U-type ferrite core - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of inductance even when there is irregularity within dimensional tolerance by a method wherein the junction surface at the tip of a leg part is left in an unpolished state, and the junction surface at the tip of the leg part on the opposite side of a coil is formed in a tapered surface inclined toward the inside. CONSTITUTION:Tapered surfaces 1c and 2c which are inclined toward the inside are formed on the core junction surface on the tip part of the leg parts 1b and 2b on the opposite side of the coil 3 of the U-shaped ferrite cores 1 and 2 having an unpolished junction surface on the tip of the leg part. The leg parts 1a and 2a of the ferrite cores 1 and 2 are inserted into the coil 3, they are connected through the intermediary of a molding material 4, the tapered surfaces 1c and 2c of the leg parts 1b and 2b on the opposite side are opposingly positioned, they are clamped from the back using a clamping metal fitting 7, and inductance is adjusted by applying pressure using the pressure-bonded terminals 5 and 6 from the back of the leg parts 1a and 2a. As a result, the induction can be adjusted easily.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in flyback transformers (hereinafter referred to as FBT) for TVs and monitor displays having cathode ray tubes, or transformers for high-voltage power supplies in copying machines, etc. This article relates to U-shaped ferrite cores for transformers.

[Conventional technology]

Generally, the electromagnetic characteristics of a transformer core vary greatly depending on the state of the gap that blocks the magnetic flux inside the core. For this reason, in order to achieve specific electromagnetic characteristics in a transformer, it is necessary to set an appropriate gap. The desired electromagnetic characteristics have been achieved by inserting a spacer gap. However, with such dimensions, an increase in cost due to polishing is unavoidable, so recently a cheaper method in which the core is not polished has been adopted.

Figure 2 shows an F using a conventional unpolished U-shaped ferrite core.
In Figure 0, which is a cross-sectional view of BT, (1) and (2) are U
shaped ferrite core, (3) is a transformer coil, (4)
(5) and (6) are crimp terminals, and (7) is a clamp fitting.

Next, a method for assembling the FBT and adjusting the gap will be explained. First, insert one leg (2a) of the lower ferrite core (2) into the transformer coil (3), and then insert the coil (
3) Attach the molding material (4) to the internal core joint surface0
Next, the negative leg (1a) of the upper ferrite core (1)
from the other side of the transformer coil (3), and tighten the clamp fitting (7) so that the upper and lower cores (1) and (2) do not overlap.
) to temporarily fix the legs (1b) and (2b) of the cores (1) and (2) on the opposite side of the coil (3) from the back, using the clamping force of the clamp fittings (7). This is to prevent the material (4) from being compressed.

Next, the legs (la) of the cores (1) and (2) on the coil (3) side
), (2a) are gradually pressurized from the back using crimp terminals (5) and (6). At this time, the inductance between specific terminals of the transformer coil (3) is simultaneously measured, and when the inductance reaches the desired value, the crimp terminal (5), (
6) Stop pressurizing. The mold material (4) is semi-solidified to improve work efficiency, and the crimp terminals (5), (
After removing 6), complete solidification treatment is performed in the next step.

[Problem that the invention seeks to solve]

However, in such a conventional U-shaped ferrite core, when assembling and adjusting a transformer using an unpolished core, for example, as shown in Fig. 3, the ferrite core (1)
, (2) are within the dimensional tolerance, and if the legs (1b) and (2b) on the opposite side of the coil (3) are deformed outward due to the gap between the legs, etc., the crimp terminal (5) after adjusting the inductance ,(
6) is removed, the clamping force of the clamp fitting (7) applies a rotational force using the inner joint of the legs (1b) and (2b) as a fulcrum, which causes the leg (3) inside the coil (3) to rotate. There was a problem that the gap size of 1a) and (2a) increased, resulting in poor characteristics.

This invention was made to solve the above-mentioned problems, and even if the unpolished U-shaped ferrite core has some variation within its dimensional tolerance, it can easily and easily adjust the inductance without any trouble. The purpose is to provide a U-shaped ferrite core that can be formed with high precision.

[Means for solving problems]

The U-shaped ferrite core according to the present invention has a U-shaped ferrite core, and in the U-shaped ferrite core, in which two cores are formed facing each other so that one leg is inserted into a coil, each of the legs has a U-shaped ferrite core. The joint surface at the tip is unpolished, and the joint surface at the tip of the leg on the opposite side from the coil is a tapered surface that slopes inward.

[For production]

In the U-shaped ferrite core of this invention, the leg on the side where no tapered surface is formed is inserted into the coil and joined via a molding material, the tapered surface of the leg on the opposite side to the coil is opposed, and Clamp. Then, the inductance is adjusted by applying pressure to the coil-side leg from the back using a crimp terminal.

Even if the crimp terminal is removed after adjusting the inductance, the clamp applies rotational force to the ferrite core using the outer joint of the leg on the opposite side of the coil as a fulcrum, so no force is applied to pull the leg on the coil side apart. .

At this time, a force is applied to the leg on the coil side to compress the molding material, but this force is negligible compared to the pressure applied by the crimp terminal. Therefore, the gap dimension formed inside the coil is maintained stably.

〔Example〕

FIG. 1 is a sectional view of an FBT using an unpolished U-shaped ferrite core according to an embodiment of the present invention.

In the figures, (1) to (7) indicate the same or equivalent parts as in FIGS. 2 and 3. Ferrite core (1), (2
) is provided with an inwardly inclined taper surface (lc
).

(2c) is formed. The other configurations are the same as in FIG. 2.

In the U-shaped ferrite core configured as above, ferrite cores (1), (2)
The legs (1a) and (2a) of the coil (3) are inserted into the coil (3) and joined via the mold material (4),
), (2b) with the tapered surfaces (1c) and (2c) facing each other, clamp them from the back with the clamp fittings (7), and then clamp the legs (
The inductance is adjusted by pressurizing the backs of 1a) and (2a) with crimp terminals (5) and (6). Even if crimp terminals (5) and (6) are removed after adjustment, the ferrite core (1)
, (2) is subjected to a rotational force using the outer joint of the legs (1b), (2b) as a fulcrum by the clamp fitting (7), so the legs (1a), (2a) are separated. There is no
Ferrite cores (1) and (2) formed in the coil (3)
) is kept stable.

Therefore, as shown in Figure 3, ferrite cores (1) and (2)
Even if the legs (1b) and (2b) are deformed during firing, when the crimp terminal is removed after adjusting the inductance,
The dimensions of the gap do not change.

In this way, it is possible to improve the yield during the production of ferrite cores, and it is possible to provide inexpensive ferrite cores.

〔Effect of the invention〕

As described above, according to the present invention, since tapered surfaces are formed on the legs of the U-shaped ferrite core, it is possible to easily and accurately adjust a transformer using an unpolished ferrite core.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an FBT using a U-shaped ferrite core according to an embodiment of the present invention, and FIGS.
1 is a cross-sectional view of an FBT using a shaped ferrite core. In each figure, the same reference numerals indicate the same or corresponding parts. (1), (2) are ferrite cores, (la), (lb
), (2a), (2b) are legs, (1c), (2c) are tapered surfaces, (3) is a transformer coil, (4) is a molding material, (5), (6) are crimp terminals, ( 7) is a clamp fitting.

Claims (1)

[Claims] (1) In a U-shaped ferrite core that has a U-shape and is made by placing two pieces facing each other so that one leg is inserted into the coil to form a core, the joint surface at the tip of each leg is unpolished. A U-shaped ferrite core characterized in that the joint surface of the end of the leg on the opposite side from the coil is a tapered surface that slopes inward.