JPH02244606A - Core for small-sized transformer - Google Patents

Abstract

PURPOSE:To reduce the distance between the right and left legs without lowering the efficiency of a transformer by utilizing the space of the gap formed in the small-sized transformer. CONSTITUTION:In the cores 11 and 12 of a small-sized transformer, the yoke 11a and the right and the left legs 11c and 11d are swelled up in such a manner that they are bending toward outside, and the curved face is corresponded to the gaps 26a and 26b formed between a bobbin 24 and a coil 23. The leg faces, which come in contact with the upper side 11b1 and the lower side 11b2, of the above-mentioned legs are formed in curved shape so that they are buried in the gaps 26a and 26b through the intermediary of the bobbin 24. As a result, the lateral length of the transformer can be made short, and the transformer can be made small in size.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention is applicable to flash discharge light emitting devices for photography, cameras, televisions, small electronic dividers, and other general electric equipment and communication equipment. This article relates to cores used in small transformers.

[Prior Art] Although there are various types of small transformers, the most widely known small transformer is one using an E-E type core.

FIG. 8 is a longitudinal sectional view showing an example of this type of small transformer;
FIG. 9 is a perspective view of the core of the small transformer shown in FIG. 8.

In the figure, 21.22 indicates an E-shaped core, which is formed into the same shape by firing ferrite powder, and each has a yoke portion 21a, 22a, a central leg 21b,
22b, left and right #21c, 22C121, d, and 22d, and the end surfaces of these legs are joined and fixed to form a closed magnetic path.

That is, the E-shaped core 21.22 has central legs 21b, 2
2b has a long rectangular cross section in the left and right leg direction, and is offset so that its lower side is flush with the lower sides of the rectangular yoke parts 21a and 22.1.

Further, the left and right legs 21c, 22e, 21d, and 22d extend from both ends of the yoke portions 21-a and 22a.

These are formed to have the same width and thickness as the yoke portions 21a and 22a.

FIG. 10 shows a cross section of the core 21, in which the central leg 21b has a vertical length of 21L and a horizontal length of 21. The core 21 has a vertical length of 21M and a horizontal length of 21N, and the cross-sectional area S1 of the central leg 21b is the sum of the cross-sectional area S2 of the left leg 21e and the cross-sectional area S1 of the right leg 21d. It has an equal cross-sectional area.

Note that the core 22 also has the same configuration as the core 21 described above.

The cores 21 and 22 configured as above are at the center #2.
1b and 22b are inserted into the rectangular tube part from both sides of the bobbin 24 on which the coil 23 is wound, and the left and right legs 21e, 22c, 2
id and 22d are projected outside the coil 23, and each end face is bonded and fixed.

The coil 23 is previously wound around a bobbin 24 as shown in FIG. 11, and slight gaps 26a and 26b are formed at the upper and lower sides of the bobbin 24. In addition, coil 2
The end of 3 is implanted in the bobbin 24 and fixed to the terminal pin 25.

[Problems to be Solved by the Invention] This kind of small transformer explained above in the conventional example is always required to have a smaller and flatter outer shape, and in order to meet this request, the conventional example has a core 21 as shown in FIG. The central legs 21b and 22b of .22 are connected to the yoke portion 21. a, 22a has a cross-sectional shape that is long in the long side direction and has a wall thickness that is sufficiently smaller than the width in the short side direction.

In general, it is necessary for small transformers to be made smaller without reducing efficiency. For this reason, the center leg has an equal cross-sectional area as the entire left and right legs, and the area between the center leg and the left and right legs generates a specified output. It is necessary to secure the minimum necessary spatial distance for coil winding.

For this reason, it has become an extremely difficult problem to further downsize the conventional small transformer.

Therefore, the present invention focuses on the gaps 26a and 26b formed in conventional small transformers, and aims to develop a core for a transformer that can make use of this small space and further reduce the size of the transformer. .

"Means for Solving the Problems" In order to achieve the above object, the present invention provides a core for a small transformer in which a center leg, left and right legs, and a yoke are integrally formed of a ferrite material. , left and right legs extending from both ends of the yoke portion in the longitudinal direction;
It has a central leg extending parallel to the left and right legs, and the central leg is long in the long side direction of the yoke part width and has a wall thickness sufficiently smaller than the width in the short side direction. We propose a core for a small transformer, characterized in that at least one shoulder surface corresponding to the long side has a shape that bulges out in a curved manner toward the outside of the leg.

``Function'' The central leg of the core for a small transformer has a cross-sectional shape that is long in the long side direction of the yoke part width and has a wall thickness sufficiently smaller than the width in the short side direction, and the shoulder surface corresponding to the long side of the cross-sectional shape is long. Since at least one surface of the leg is curved outward, the width of the long side of the cross-sectional shape of the central leg is shortened by the amount of increase in the core due to the curved shape.

As a result, the length between the left and right legs can be shortened without reducing the efficiency of the small transformer.

"Example" Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a small transformer using a ferrite core showing a first embodiment, and FIG. 2 is a sectional view of the core of the small transformer shown in FIG. 11.

This small transformer consists of a core 11.12 of the same shape made of ferrite material and a coil 13. Bobbin 14, terminal bin 1
It is composed of 5.

The cores 11, 12 are of substantially the same construction as the cores 21, 22 described in FIGS. 8-10, except for the central leg.

Note that since the cores 11 and 12 have the same shape, only the core 11 will be described.

That is, as can be seen from FIG. 9, the core 11 has the same configuration as the yoke lla, the left and right legs 11c, and the lid, and the shoulder surfaces corresponding to the upper side 11b1 and lower side 11b2 of the central leg 11b are curved outward. It has a bulging shape.

The upper side 11b□ and the lower side 11b of the center #11b.

The curved surfaces are formed to correspond to the gaps 26a and 26b formed between the bobbin 24 and the coil 23 shown in FIG.

As shown in FIG. 3, the bobbin 14 is curved so that the central leg 11b can be inserted therein, and the coil 13 is wound around the circumferential surface of the bobbin 14.

In a small transformer constructed as in Kitagi, the central leg 11. of the core 11. Since the cross-sectional area of the central leg 1.1b is expanded in the vertical direction, the lateral length of the central leg 1.1b can be reduced in accordance with the amount of expansion, and the entire small transformer can be downsized.

This will be explained with reference to the conventional core 21 shown in FIG.

Generally, in order to reduce the size of this type of small transformer without sacrificing operational performance, the center leg should have an equal cross-sectional area as the entire left and right legs, and a predetermined output should be generated between the center leg and each of the left and right legs. It is designed to provide the minimum space distance that allows the coil to be wound.

Therefore, the present invention focuses on the gaps 26a and 26b between the bobbin 24 and the coil 23 shown in FIG. The peripheral surface corresponding to the lower side 11b2 is curved, and the length of the central leg 11b in the horizontal direction is reduced by the increase in the amount of iron in the vertical direction. However, the center leg 11b is the center leg 2 of the core 21 shown in FIG.
, L b have equal cross-sectional areas.

In other words, the longest length in the vertical direction of the center 11111b is 11-7,
Assuming that the lateral length is 11R1 and the cross-sectional area is 84, the cross-sectional area S4 of the central leg 11b is made equal to the cross-sectional area S1 of the central leg 21b of the core 21 shown in FIG. 26b is filled through the bobbin.

Therefore, the length in the vertical direction is ILL>21L, and the length in the horizontal direction is 1.1. Since R<21R, the center leg 11b can be reduced in lateral length by 21R-11R.

On the other hand, the cross-sectional areas of the left and right l111c and lid are Ss and SG
Then, these are the cross-sectional areas S2 of the left and right legs shown in FIG.
．． Let the cross-sectional area be equal to S.

As a result, the longitudinal length IIM of the core 11 and the longitudinal length 21M of the core 21 are equal, but the lateral length IIN of the core 11 is smaller than the lateral length 21N of the core 21, resulting in a small size. The shape of the transformer is made smaller.

FIG. 4 is a vertical sectional view of a small transformer using a ferrite core showing a second embodiment, and FIG. 5 is a perspective view of the core shown in FIG. 4.

The small transformer of this embodiment is composed of cores 16 and 17 of the same shape made of ferrite material, a coil 18, a bobbin 19, and a terminal pin 20.

The cores 16 and 17 are rectangular plate-like yoke parts i6a, 17
a, central legs 16b, 17b protruding from the center of these yoke parts 16a, 17a, and these yoke parts 16a, 17a.
Left and right legs 16c, 17e, 16d, and 17d extending parallel to the center legs 16b and 17b from both ends thereof are integrally formed.

FIG. 6 shows a cross section of the core 16, in which a fitting groove 16e formed on the long side of the yoke portion 16a passes through from the inside toward the outside.

As shown in the figure, the central leg 16b has a circumferential surface corresponding to its upper side 16bi and lower side 16b that is curved so as to bulge outward, and its left and right sides have a constant slope,
The overall cross-sectional shape is trapezoidal.

The diagonal sides of left and right legs 1.6e and 16d are the center leg 16b
It forms a nearly triangular cross section that faces parallel to the inclination of.

The core 16 configured as described above has the upper side 1 of the central leg 16b.
6b1 and the lower side 16b2 are curved outward, which is different from the core 11 of the first embodiment shown in FIG.
Similarly, the gaps 26a and 26b shown in FIG. 11 are formed so as to be filled through the bobbin.

As a result, compared to a core in which the peripheral surface corresponding to the upper and lower sides of the center leg is flat, the amount of iron in the horizontal direction increases by an increase in the amount of iron of 16L in length in the vertical direction, as in the case of the first embodiment. length 16
Since R is reduced, the lateral length 16N of the core 16 can be reduced while the vertical length 16M remains unchanged. The same applies to the core 17.

Therefore, if the central legs 16b and 17b of these cores 16 and 17 are inserted into the bobbin 19 on which the coil 18 is wound, the coil 18 will come into contact with the periphery of the bobbin 19 as shown in FIG. The entire small transformer is reduced in size by winding.

Note that the present invention applies to the first embodiment if the core has a cross-sectional shape of the central leg that is longer in the horizontal direction than the length in the vertical direction.

The present invention is not limited to the core shown in the second embodiment, and can be implemented in the same manner, and can also be implemented in a similar manner to a transformer in which a coil is wound directly around the central leg of the core.

"Effects of the Invention" As explained above, the core according to the present invention has a cross-sectional shape in which the central leg is long in the long side direction of the yoke width, has a wall thickness sufficiently smaller than the width in the short side direction, and By making at least one side of the shoulder surface corresponding to the long side of the leg curved outward, the amount of iron can be effectively increased. The directional length is reduced, and as a result, the transformer configuration is reduced compared to conventional products.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a small transformer using a ferrite core showing a first embodiment of the present invention, FIG. 2 is a sectional view of the core shown in FIG. 1, and FIG. 4 is a longitudinal sectional view of a small transformer using a ferrite core showing a second embodiment of the present invention, FIG. 5 is a perspective view of the core shown in FIG. 4, and FIG. Cross-sectional view of the core shown in Figure 7
The figure is a sectional view taken along line B-B in Fig. 4, Fig. 8 is a longitudinal sectional view of a small transformer showing a conventional example, Fig. 9 is a perspective view of the core of the small transformer shown in Fig. 8, and Fig. 10 is a longitudinal sectional view of a small transformer shown in Fig. 8. FIG. 9 is a sectional view of the core, and FIG. 11 is a sectional view taken along the line CC in FIG. 8. 11.12...Core 11a...Yoke portion 11b...Central leg 1c...Left leg 1d...Right leg 3...Coil 4...Bobbin 5...Terminal pin 6.17 ...Core 6a, 17a...Yoke part 6b, 1.7' b...Central leg 6c, 17c...Left leg 6d, 17d...Right leg 8...Coil 9...Bobbin O...Terminal Bin 1m Figure 2 Figure Patent Applicant Kijima Co., Ltd. Agent Rishi Ii Hiroharu Koike Figure Figure Figure Figure Figure Figure Figure

Claims (1)

[Claims] In a core for a small transformer in which a center leg, left and right legs, and a yoke part are integrally formed of ferrite material, the yoke part is a rectangular plate shape, and the left and right legs extend from each end in the long side direction of this yoke part, and the left and right legs are made of a ferrite material. The central leg extends parallel to the legs, and the central leg has a cross-sectional shape that is long in the long side direction of the yoke part width, and has a wall thickness that is sufficiently smaller than the width in the short side direction. A core for a small transformer, characterized in that at least one of the leg surfaces corresponding to the sides has a shape that bulges out in a curved manner toward the outside of the leg.