JPH0534816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small transformer, and particularly proposes a small transformer suitable for a power transformer.

As is well known, most power transformers are equipped with a shielding device because power transformers receive electromagnetic interference from load circuits, and vice versa.

A first object of the present invention is to reduce the above-mentioned electromagnetic interference as much as possible.

Moreover, since small power transformers and the like are installed in a limited space together with other electrical components, they are susceptible to electrical damage due to contact with other electrical components.

A second object of the present invention is to provide an external structure with high electrical resistance and excellent nonflammability (also flame retardancy and self-extinguishing properties) in order to prevent such electrical disturbances.

Furthermore, a third object of the present invention is to propose a compact transformer that is flattened by limiting the height of the transformer as much as possible in order to facilitate installation.

A fourth object of the present invention is to provide a practical compact transformer with as many terminal pins as possible.

Therefore, the small transformer according to the present invention has a lower surface and one side surface open, an upper surface and another circumferential side surface as a peripheral core, and a horizontally elongated rectangular shape projecting from approximately the center of the other side surface to the above one side surface. A bobbin includes two box-shaped cores of the same shape having internal legs in cross section, a rectangular cylindrical winding portion with square flanges at both ends, and a terminal pin fixed to the lower end surface of these rectangular flanges. A coil is wound around the winding part and the coil end is fixed to the terminal pin, and the two box-shaped cores are assembled to the bobbin by inserting the internal legs from the outside of each of the square flanges of the bobbin. At the same time, one side of each box-shaped core is fixed against each other, and the outer periphery of the coil except for the lower surface side is surrounded by the box-shaped core.

Examples of the present invention will be described below to further clarify the content of the present invention.

FIG. 1 is a perspective view of a small transformer according to the present invention;
Figure 2 is a bottom view of the transformer, Figure 3 is a vertical sectional view of the transformer taken along line A-A in Figure 1, and Figure 4 is a cross-sectional view taken along line B-B in Figure 1. FIG. 3 is a vertical cross-sectional view of the transformer.

In these drawings, 1 and 2 are transformer cores of the same shape made of ferrite material, and these cores 1 and 2 are hollow hexahedrons having faces 1a to 1f and 2a to 2f. It is provided with internal legs 1g and 2g integrally formed with an octagonal cross section.

FIG. 5 is an exploded perspective view showing the transformer cores 1 and 2 in detail. As can be seen from this figure, the stepped portions 1h and 2h (2h (not shown) and stepped portions 1i and 2i formed along the lower edge of the core.

In addition, in FIGS. 1 to 4, reference numeral 3 denotes a bobbin around which at least two or more coils 4 are wound.
This bobbin 3 has the form shown in FIG. That is, the cylindrical portion 3a into which the internal legs 1g and 2g are inserted has a flange portion 3b at both ends, and a predetermined number of coils 4 are wound between the flange portions. Said cylindrical part 3
A is a polygonal cylinder that matches the cross-sectional shape of the internal legs 1g and 2g, and the upper and lower horizontal sides are sufficiently thinner than the other parts. (See Figures 4 and 5) Further, a thick terminal pin receiver 3c is formed at the lower part of the flange 3b, and a stepped flange 3d is formed at the lower end of the flange 3b. .

In addition, reference numeral 5 in the drawings indicates an insulating tape wrapped around the coil 4, 6 indicates a terminal pin, and 3 indicates a terminal pin.
e is a guide groove at the end of the coil.

In the small transformer having the above structure, first, a bobbin 3 is wound with a plurality of coils 4, and then each coil end is fixed to a terminal pin 6, and then the transformer cores 1 and 2 are connected from both sides of the bobbin 3. As each core is inserted, the joint surfaces of these cores 1 and 2 are fixed with adhesive.

The transformer assembled in this way is shown in Figure 1~
As can be seen from FIG. 4, there are the following effects.

(1) Since the entire outer periphery except the bottom surface is covered with a ferrite core, this outer periphery core forms a magnetic path as a transformer and at the same time functions as a magnetic shield.

(2) The lower end of the bobbin flange 3b is connected to the transformer cores 1 and 2.
Since it is located inside from the lower edge of the transformer, the soldering part that fixes the coil end to the base of the terminal pin 6 does not protrude from the bottom of the transformer. Electrically and mechanically stable when a transformer is installed.

(3) A stepped portion 1i formed by a stepped flange 3d provided on the bobbin 3 at the lower edge of the transformer cores 1 and 2,
2i, electrical insulation between the terminal pin 6 and the lower edge of the transformer cores 1 and 2 is ensured.

(4) The above-described transformer in which the internal legs 1g and 2g are horizontally elongated is a small flat transformer, but by making the horizontal side of the bobbin cylindrical portion 3a thinner, it can be made even more flat and effective. .

That is, the internal legs 1g and 2g have an octagonal cross section with each corner of a rectangle cut out,
A bobbin cylindrical portion 3a into which these internal legs 1g and 2g are fitted is formed into an octagonal cylinder to match the internal legs 1g and 2g. In this case, the horizontal side 3a1 of the bobbin cylindrical part 3a is the oblique side 3.
Since it is supported by a2, this horizontal side part 3
The wall thickness of a1 can be reduced.

When the bobbin cylindrical portion 3a is simply a square tube and the horizontal side portion 3a1 is made thin, the horizontal side portion 3a1 often breaks more than the vertical side portion 3a3 during the manufacturing process of windings and other transformers. .

As described above, by making the horizontal side portion of the bobbin cylindrical portion 3a thinner, the height of the transformer can be reduced by the thinner portion.

Further, the horizontal side portion 3a1 described above may be removed to form a through hole. Since the winding portion of the bobbin 3 is formed by the oblique side portion 3a2 and the vertical side portion 3a3, sufficient strength is maintained.

When the horizontal side portion 3a1 is formed as a through hole, an insulating tape may be wrapped around the winding portion of the bobbin 3, and the wire may be wound thereon.

The form of the small transformer mentioned above has a width L of approximately
25.9mm, depth width D is approx. 26.5mm, height H is approx.
21.8 mm, and the bobbin cylindrical portion 3a has a horizontal side portion 3a1 of approximately 0.4 to 0.5 mm and an oblique side portion 3a2.
And the vertical side portion 3a3 is formed to have a thickness of about 1 mm. Therefore, compared to the case where the bobbin cylindrical part 3a is formed with the same wall thickness, the height of the transformer is reduced by 1 mm.
In addition, if the horizontal side part 3a1 is removed and formed as a through hole, the height of the transformer can be reduced to 2 mm.
It can be done to a lesser extent.

The ability to reduce the height of the above-mentioned small transformer by 1 to 2 mm is an extremely large advantage.

(5) By making the internal legs 1g, 2g and the bobbin cylindrical portion 3a have an octagonal cross section as described above, the beveled surfaces 1b,
1d, 2b, and 2d can be formed. These beveled surfaces, together with the above-mentioned reduction in height, make the transformer even flatter.

(6) By using a core with horizontally elongated internal legs, the terminal pin receiver 3c of the bobbin 3 in which the terminal pins 6 are implanted can be formed wide, and thereby a large number of terminal pins 6 can be provided. With,
Since a sufficient width can be provided between each terminal pin, it becomes a safe and practical small transformer.

Next, FIGS. 7 and 8 show an embodiment in which a ferrite plate 7 is fixed to the bottom of the above-mentioned small transformer, and a small hole 7a provided in the ferrite plate 7 is filled with an insulating material, such as an epoxy material, inside the transformer. It is for filling.

According to this embodiment, since almost the entire periphery of the transformer is covered with the ferrite core, the magnetic shielding effect is greatly enhanced.

In the above embodiment, the ferrite plate 7 is fitted into the stepped portions 1i, 2i of the ferrite cores 1, 2, but as shown by the phantom lines in FIG. Alternatively, the ferrite plate 7 can be replaced with another magnetic plate such as a metal plate.

As mentioned above, the small transformer according to the present invention is
Since the outer periphery of the coil except for the bottom side is covered with a ferrite core, magnetic interference with or influence from external circuits can be effectively prevented. Because it is curved, it becomes a small transformer that is sufficiently flattened.

Furthermore, since many terminal pins can be provided on the square flanges formed at both ends of the winding portion, a practical small transformer can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a small transformer showing an embodiment of the present invention, FIG. 2 is a bottom view of the small transformer,
Figure 3 is a sectional view of the small transformer taken along line A-A in Figure 1, and Figure 4 is B in Figure 1.
-A cross-sectional view of the small transformer taken along line B, Figure 5 is an exploded perspective view of the ferrite core, and Figure 6 is an exploded perspective view of the ferrite core.
The figure is a perspective view of the bobbin, Figure 7 is a bottom view of a small transformer showing another embodiment of the present invention in which a ferrite plate is fixed to the bottom of the transformer, and Figure 8 is the same figure as Figure 4. FIG. 3 is a cross-sectional view of the transformer. 1, 2...Transformer core, 1g, 2g...Internal leg, 1i, 2i...Stepped portion, 3...Bobbin, 3a
... Cylindrical portion, 3b... Flange portion, 3d... Stepped flange, 4... Coil, 6... Terminal pin, 7... Ferrite plate.

Claims (1)

[Claims] 1. 2 of the same shape, which has an open bottom surface and one side surface, has an upper surface and another circumferential surface as a peripheral core, and has internal legs that protrude from approximately the center of the other side surface to the one side surface and have a horizontally long rectangular cross section. A bobbin has two box-shaped cores, a rectangular cylindrical winding portion with square flanges at both ends, terminal pins are fixed to the lower end surfaces of these square flanges, and a coil is wound around the winding portion of the bobbin. and a coil whose part is fixed to the terminal pin, and the internal leg is inserted from the outside of each square collar of the bobbin.
A small transformer characterized in that two box-shaped cores are assembled to a bobbin, one side of each box-shaped core is fixed against each other, and the outer periphery of the coil except for the bottom side is surrounded by the box-shaped core. .