JPH088172B2 - Small transformer core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application" The present invention relates to a flash discharge emitter for photography, a camera,
The present invention relates to a ferrite core used for a small transformer used in a television, a small electronic computer, other general electric devices and communication devices.

"Prior Art" There are various types of small transformers, and the most widely used transformer uses an EE type core.

FIG. 13 is a vertical sectional view showing an example of this type of small transformer, and FIG. 14 is a sectional view taken along the line AA in FIG.

The E-shaped cores 1 and 2 are formed into the same shape by firing ferrite powder, and each has a central leg 1a, 2a and left and right legs 1b, 2b, 1c,
2c, and the end surfaces of these legs are joined and fixed to form a closed magnetic circuit.

As can be seen from the perspective view of FIG. 15, the E-shaped cores 1 and 2 have central legs 1a and 2a each having a rectangular cross section that is long in the left-right leg direction, and the lower side surface thereof is flush with the lower long side of the rectangular yoke portion. The left and right legs 1b, 2b, 1
The c and 2c are extended from both ends of the yoke portion and have the same width and wall thickness as the yoke portion.

In the E-shaped cores 1 and 2 described above, their central legs 1a and 2a are inserted into the rectangular tube holes of the bobbin 4 around which the coil 3 is wound.
The left and right legs 1b, 2b, 1c, 2c are joined and fixed to the end faces of the legs so as to project to the outside of the coil.

The coil 3 is formed by being wound around the bobbin 4 in advance, but the coil end portion is fixed to the terminal pin 5 embedded in the bobbin 4.

"Problems to be Solved by the Invention" It is an important problem to reduce the size of a small transformer without lowering its efficiency.

The compact transformer of the above-mentioned conventional example has a horizontal length L and a depth length W of 6 to 7 mm and a height H of about 5 mm. Although it has been put to practical use, there is still a demand for reduction in form.

However, if the size of such a small transformer is further reduced, it becomes extremely difficult to maintain the efficiency higher than a predetermined level, and the core may be damaged during the production or the wire may be disconnected during the winding process.

It is considered that the small transformer mentioned above can be reduced by designing the E-shaped cores 1 and 2 in a short size, but the thickness of the left and right legs of the core is about 0.8 mm, and it is thinner than this. That is, the core is often damaged during the production process and the transformer assembly work, and it is difficult to obtain a predetermined efficiency because the iron content is insufficient.

"Means for Solving Problems" The present invention was developed in view of the above problems, in which the central leg projects from the center of the yoke part, and the left and right legs project in parallel from both sides of the yoke part. A small transformer core in which the left and right legs and the yoke part are integrally formed of ferrite material, and the yoke part is a rectangular plate shape, and the central leg is a trapezoid consisting of upper and lower sides parallel to the long side of the yoke part and inclined sides on both sides. It has a cross-section and its wall thickness is smaller than the width of the yoke part. The inner surface of each of the left and right legs, which has the same width as the yoke part, is a right-angled triangle with diagonal sides that are parallel and parallel to the inclined side of the central leg. A small transformer core having a cross section and a wide fitting groove for fitting a part of the bobbin is formed by forming a notch so that the inside and outside of the yoke part communicate with each other on the lower surface side of the center leg. suggest.

[Examples] Next, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view of a small transformer using a ferrite core according to the first embodiment of the present invention, and FIG. 2 is a sectional view taken along line BB in FIG.

In these figures, 6 and 7 are cores of the same shape formed of a ferrite material, which have the shape shown in FIG. 3 (a) is a side view of the core 6 as seen from the leg end face direction, and FIG. 3 (b) is a cross-sectional view taken along the line CC of FIG. 3 (a). Although FIGS. 3 (a) and 3 (b) show only the core 6, the core 7 has the same shape as described above,
The same subscripts are attached to FIGS. 1 and 2 and the description thereof is omitted.

As shown, the core 6 has a rectangular plate-shaped yoke portion 6a.
And the central leg 6b protruding from the center of the yoke 6a.
And a left leg 6c and a right leg 6d extending in parallel with the central leg 6b from both ends of the yoke portion 6a are integrally formed.

The central leg 6b is formed as a trapezoidal cross section whose upper and lower sides are parallel to the long sides of the yoke portion 6a, as shown in the drawing. (Long side) is specified so that it does not protrude.

As shown in the drawing, the left and right legs 6c and 6d are formed in a cross section of a substantially right triangle whose diagonal sides are parallel to and oppose to the inclined side of the central leg 6b. Although the apex portion of the right triangle is cut out horizontally, the apex portion may be left as it is.

The yoke portion 6a has a laterally long fitting groove 6e on the inner surface below the base of the center leg 6b, and the bobbin portion is fitted into the fitting groove 6e.

Further, in FIGS. 1 and 2, 8 is a bobbin, 9 is a coil wound around the bobbin 8, 10 is a terminal pin to which a winding end portion of the coil 9 is fixed, and 11 is wound around the coil 9. It is insulating tape.

As shown in FIG. 4, the bobbin 8 has a rectangular tubular winding portion.
8a and collars 8b and 8c provided on both sides of the winding portion 8a are integrally formed of a synthetic resin material, and trapezoidal meat for implanting the terminal pin 10 on the lower portion of the outer surfaces of the collars 8b and 8c. The thick portions 8d and 8e are integrally formed with outwardly facing flanges 8f and 8g at the lower ends of the trapezoidal thick portions 8d and 8e.

4 (a) is a front view of the bobbin 8 and FIG. 4 (b) is a side view of the bobbin 8.

In the small transformer described above, the bobbin 8 is wound in advance and the coil 9 is wound, and then the central legs 6b and 7b of the cores 6 and 7 are inserted into the winding portion 8a of the bobbin 8 so as to face each other. Then
Secure the legs with their end faces joined. An adhesive is used for this fixing.

The central legs 6b and 7b should be slightly shorter than the left and right legs,
These central legs 6b, 7b when the cores 6, 7 are assembled
You may make it form a gap between the front-end surfaces of.

In the cores 6 and 7 assembled in this way, the trapezoidal thick portions 8d and 8e of the bobbin 8 are fitted in the fitting grooves 6e and 7e, so that the winding portion between the collars of the bobbin 8 should be wide. Moreover, since the lower end surfaces of the yoke portions 6a, 7a of the cores 6, 7 are joined to the upper surfaces of the flanges 8f, 8g, each terminal pin 10 (or the fastening portion at the winding end portion) and the cores 6, 7 are The above is electrically insulated by the flanges 8f and 8g.

In addition, the plate width of the yoke portions 6a, 7a is widened and the central legs 6b, 7b are located substantially in the center thereof, whereby the wall thickness of the yoke portions 6a, 7a can be reduced. 6c, 7c, 6
Since d and 7d have the same width as the yokes 6a and 7a, their cross-sectional areas are sufficient, and as a result, the lateral length L ₁ and depth length W ₁ of the small transformer are compared to the conventional small transformer. And shortened. The height H ₁ is about the same as in the conventional example in the case of this embodiment, but the slanted side of the trapezoidal cross section of the central legs 6a and 7a
Further flattening can be achieved by forming the diagonal sides of the triangular cross sections of 6c, 7c, 6d, and 7d so as to be more inclined.

In particular, in the cores 6 and 7 used in this small transformer, the left and right legs 6c, 7c, 6d, and 7d have a substantially right-angled triangular cross section, and as a result of the increase in the thickness of the bottom part, the left and right legs have high mechanical strength. It is advantageous in that they can be prevented from being damaged.

FIG. 5 shows a modification of the first embodiment, which is characterized in that the core 12 has curved surfaces 12f and 12g above the inner surfaces of the left and right legs 12c and 12d. The other parts are the same as the cores 6 and 7, and the same parts are represented by common subscripts.

In the core 12 thus implemented, the cross-sectional areas of the left and right legs 12c and 12d can be increased, and the curved surfaces 12f and 12g serve as reinforcing portions that prevent damage to the left and right legs.

Further, the small transformer using the ferrite core according to the present invention may be provided with an upper cover plate 13 as shown in FIGS. 6 and 7. The upper cover plate 13 is a quadrilateral plate member shown in FIGS. 8A and 8B, and is fixed to the upper surfaces of the cores 6 and 7 with an adhesive or the like.

When the upper cover plate 13 is made of a magnetic material, it is given to an external circuit,
Alternatively, it is possible to prevent a magnetic path induction failure received from an external circuit. The upper cover plate 13 may be made of a non-magnetic material and is effective for protecting the coil 3. Also, the upper lid plate described above
13 can be used as a nameplate for displaying a product name, a manufacturer name, and the like.

On the other hand, if the lower cover plate 14 similar to the upper cover plate 13 described above is provided, it is more effective for prevention of electromagnetic induction damage and coil protection.

6 is a vertical sectional view of the small transformer, and FIG. 7 is a sectional view taken along the line DD in FIG.

FIG. 9 is a vertical sectional view of a small transformer using a ferrite core according to the second embodiment of the present invention, and FIG. 10 is a sectional view taken along the line EE in FIG.

In these figures, 15 and 16 are cores of the same shape made of ferrite material, 17 is a bobbin, 18 is a coil, 19 is a terminal pin, and 20 is an insulating tape, which are assembled in the same manner as the small transformer of the first embodiment. There is.

The core 15 is, as shown in FIGS. 11 (a) and 11 (b),
The fitting groove 15e formed in the lower portion of the yoke portion 15a penetrates from the inside to the outside, which is different from the cores 6 and 7 described above. The same applies to the core 16.

FIGS. 12A and 12B show the bobbin 17. For such cores, 15, 16, the trapezoidal thickened portion 17 of the bobbin 17 is
Since d and 17e are fitted as shown in FIG. 9, the winding portion between the bobbin collars can be enlarged. The other structure is the same as that of the first embodiment, and the curved surfaces 12 of the left and right legs shown in FIG.
f, 12g, upper cover plate 13 and lower cover plate 14 shown in FIGS. 6 to 8
Can be similarly provided.

[Advantages of the Invention] As described above, the ferrite core according to the present invention is provided with the central leg of the trapezoidal cross section in the substantially central portion of the rectangular yoke portion, and the inner surface of the triangular cross section parallel to the inclined side surface of the central leg. Since the legs are provided, the mechanical strength of the left and right legs can be increased, damage to the core can be prevented during the core production process, transformer assembly process, etc., and the cross-sectional area of the left and right legs can be made effective. Since the number of cores can be increased, the core can be shortened according to the increase, so that the transformer configuration is reduced as compared with the conventional product.

Further, since the fitting groove for fitting a part of the bobbin is provided, the winding part of the bobbin can be enlarged, and the transformer efficiency does not decrease even if the transformer form is reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a compact transformer using a ferrite core according to the first embodiment of the present invention, and FIG.
3B is a cross-sectional view taken along the line B, FIG. 3A is a side view seen from the leg end surface direction of the ferrite core, and FIG. 3B is FIG. 3A.
FIG. 4 (a) is a front view of the bobbin used for the small transformer, FIG. 4 (b) is a side view of the bobbin, and FIG. 5 is a modified example of a ferrite core. 3A is a side view similar to FIG. 3A, FIG. 6 is a longitudinal sectional view of the small transformer provided with an upper cover plate and a lower cover plate, and FIG. 7 is a D-D line in FIG. Sectional view, FIG. 8 (a) is a front view of the upper cover plate, FIG. 8 (b) is a side view of the upper cover plate, and FIG. 9 is a small size using a ferrite core according to a second embodiment of the present invention. Fig. 10 is a longitudinal sectional view of the transformer, Fig. 10 is a sectional view taken along the line EE in Fig. 9, and Fig. 11 (a) is a side view of the ferrite core of the second embodiment as seen from the leg end face direction, Fig. 11 ( b) is a sectional view taken along line F-F in FIG. 11 (a), FIG. 12 (a) is a front view of the bobbin used in the small transformer of FIG. 9, and FIG. 12 (b) is a side surface of the bobbin. Figures and 13 are conventional Longitudinal sectional view of a compact transformer shown as, FIG. 14 is a sectional view along line A-A of the diagram 13, Fig. 15 is a perspective view showing a conventional example of a ferrite core. 6, 7 ...... Core, 6a, 7a ...... Yoke part 6b, 7b ...... Center leg, 6c, 7c ...... Left leg 6d, 7d ...... Right leg, 6e, 7e ...... Mating groove 8 ...... Bobbin, 8d, 8e …… Trapezoidal thick part 12, 15, 16 …… Core 15e …… Mating groove.

Claims (1)

[Claims] 1. A small transformer core in which a central leg protrudes from the center of a yoke portion in parallel with left and right legs extending from both sides of the yoke portion, and the central leg, the left and right legs, and the yoke portion are integrally formed of ferrite material. The yoke is a rectangular plate,
The center leg has a trapezoidal cross section consisting of upper and lower sides parallel to the long side of the yoke part and inclined sides on both sides, and its thickness is set smaller than the width of the yoke part. The inner surface has a substantially right-angled triangular cross-section with diagonal sides that face each other in parallel to the inclined side of the central leg, and a notch is formed so that the yoke portion on the lower surface side of the central leg communicates with the inside and outside of the yoke portion. Small transformer core with a wide fitting groove that fits a part of the bobbin.