JPH0130282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small transformer used in flashlights for photography, cameras, lighting equipment, small electronic computers, and other general telecommunications equipment.

Most of this type of transformers use an E-E type transformer core consisting of cores 1 and 2 of the same shape as shown in Figure 1, or an E-I type transformer core (not shown), and currently, Width length of iron core A1
A transformer with a diameter of 10.2 mm, a height B1 of 11 mm, and a width C1 of 2.4 mm has been implemented, but the present invention provides an effective method for downsizing and flattening such a transformer without impairing operating performance. Suggest a method.

The size of the transformer shown in Figure 1 is determined by the horizontal length and height of the iron core, and the length between the outer peripheral surfaces of the coils protruding from the front and back of the iron core.
It is conceivable to reduce the size of the entire transformer by reducing the size of the iron cores 1 and 2, but with such a configuration, problems arise in terms of mechanical strength and magnetic iron content. That is, since the cores 1 and 2 are made of ferrite material with high magnetic permeability, if the cross-sectional area of the legs, especially the cross-sectional area of the left and right legs 1a and 2a, is made too small, the cores and transformers will be damaged during the manufacturing process.
Therefore, the current limit is to products with a cross-sectional area of approximately 4.8 x 1.2 mm.

On the other hand, it is common for the central legs 1b, 2b as inner legs to have a cross-sectional area twice that of the left and right legs 1a, 2a, respectively.
A and 2a require the minimum space distance necessary to allow winding of the coil 3 that generates a predetermined output.

For this reason, there is a limit to how much the iron cores 1 and 2 can be reduced, and when the cross-sectional area of the central legs 1b, 2b, etc. is reduced in order to force downsizing, the amount of iron may be insufficient and the specified I can't get any output.

As mentioned above, there is a limit to the reduction in size of the transformer shape, so attempts are being made to incorporate the transformer shape into devices as flat as possible.

Therefore, an object of the present invention is to downsize and flatten the shape of the transformer without impairing operating performance.

In order to achieve this object, the present invention has an inner leg on which the coil-wound body is attached, and an outer leg that is connected to the inner leg by a yoke and is located outside the coil-wound body. A transformer core with two legs is provided which is integrally formed with a ferrite material, the outer leg is formed into a plate shape, and the inner surface is curved to follow the outer circumferential surface of the coil-wound body, and the inner leg is formed into a plate shape. is formed into a plate shape parallel to the outer leg, and the inner leg is thicker and narrower than the outer leg, and one side facing the outer leg is parallel to the inner side of the outer leg. The yoke is a plate-shaped body that is narrower than the width of the outer leg and slightly wider than the width of the inner leg, and has notches on both sides in the width direction. The base portions of the legs are integrally connected, and further, the winding cylinder portion into which the inner leg is inserted, and the outer leg are integrally connected to both ends of the winding cylinder portion with peripheral portions located within the inner surfaces of the outer leg. The transformer core is assembled by inserting the inner legs into the winding cylinder from both sides of the bobbin with wire wound around the winding cylinder, and the yoke surrounding including the notch. We propose a small transformer in which the end of the winding is fixed to a terminal pin fixed to the collar of the transformer.

Embodiments of the present invention will be described below, but prior to this description, the principle of the present invention will be described.

In the transformer cores 1 and 2 in Fig. 1, the central legs 1b,
Since the cross section of the coil 2b in the direction perpendicular to the leg center is square, the outer circumferential surface of the coil 3 to be wound is almost circular as shown in FIG. 1b.
Therefore, in a transformer using such iron cores 1 and 2, the external size is determined by the horizontal length A1 of the iron core, the height B1, and the length D1 between the outer peripheral surfaces of the wound coils. determined.

Next, the iron cores 4 and 5 in Fig. 2 are replaced with the iron cores 1 and 5 in Fig. 1.
This is an example in which the iron content is the same as in 2, and the shape is flattened. As can be seen from FIG. 2b, in these iron cores 4 and 5, the central legs 4b and 5b are plate-shaped, so that the coil 6 wound thereon has an elliptical shape. Therefore, if the length between the outer peripheral surfaces of the coils protruding from the front and back of the iron cores 4 and 5 is D2, then D2<D1, and
If the core width is C2, then C2<C1, and the transformer shape has been reduced from this point of view. However, both the horizontal length A2 and the height B2 of the iron core are A2>
Since A1, B2 > B1, the overall shape of the transformer is not small. Note that 4a and 5a are left and right legs.

Iron cores 7 and 8 in FIG. 3 are examples in which the iron content is the same as in iron cores 1 and 2 in FIG. 1, and the core width is increased. In the cores 7 and 8, the central legs 7b and 8b extend in the width direction of the core, so the wound coil 9
is an ellipse with its major axis in the core width direction. With this configuration, the lateral length A3 of the iron core and the height
B3 becomes A3<A1, B3<B1, but the length D3 between the outer peripheral surfaces of the coil protruding from the front and back of cores 7 and 8 and the core width C3 become D3>D1, C3>C1, and the overall shape of the transformer is small. I haven't gotten used to it. In addition, 7a, 8
a is the left and right legs.

Iron cores 10 and 11 in Figure 4 are iron cores 1 and 2 in Figure 1.
The iron content is the same and the iron core width is expanded compared to the center legs 10b, 11b, and the left and right legs 10.
It has a plate shape extending in directions a and 11a. With this configuration, the requirements for reducing the size of the transformer shown in FIGS. 2 and 3 can be met. In other words, the length of the outer circumferential surface of the coil D4=D2, D4<D1
Therefore, the height is B4=B3, B4<B1. Also,
The horizontal length is A4>A1, but in this case, A4
is quite close to A1. Therefore, by configuring the transformer core as shown in FIG. 4, it is possible to reduce the overall shape of the transformer.

Further, the coil 12 is not in close contact with the center legs 10b and 11b, and the inner peripheral surface of the coil 12 and the center leg 1
Since there is always a void 12a between the sides of 0b and 11b, the center leg 1 is inserted to fill this void 12a.
Let 0b and 11b be oval shapes. Central leg 10b,1
If 1b is made thicker in this way, the lateral length of the leg can be reduced by that much.

On the other hand, if the core width C4 is expanded as shown in Figure 4,
Since a space 12b is created between the inner surfaces of the left and right sides 10a, 11a and the outer peripheral surface of the coil, this space 12b
The left and right legs 10a and 11a are formed so as to fill in the space.

In this way, even if the center portions of the left and right legs 10a, 11a are made thin, the amount of iron does not decrease, so it is possible to shorten the lateral length A4 of the iron core.

The transformer cores 13 and 14 shown in FIG. 5 satisfy the above conditions, and according to the cores, A5<A1, B5<B1, D5<D1, and the first
Its shape is smaller than the transformer using the iron core shown in the figure.

However, as in the embodiment shown in FIG.
14b is oval, and the left and right legs 13a, 1
Curving the inner surface of 4a into a circular shape requires advanced production technology and is therefore unsuitable for increasing production efficiency.

Therefore, in the present invention, the transformer cores 13, 1
4 is improved, and a two-legged outer iron core using the center legs 13b, 14b and the left or right leg is used, and the condition of miniaturizing the transformer shape of the transformers 13, 14 is utilized as much as possible. It is unique in that it has developed a compact, flattened transformer.

Next, FIGS. 6 and 7 show a two-legged outer iron core used in the small transformer of the present invention, and these iron cores 21 and 22 have outer legs 21a and 22 formed in plate shapes.
A polygonal curved surface is formed on the inner surface of a. Further, the inner legs 21b and 22b are formed in a plate shape parallel to the outer legs 21a and 22a, and protrude in an angular shape so that one surface thereof is parallel to the inner surface of the outer legs.

Note that, as shown in the figure, the inner legs 21b and 22b are formed to have a larger wall thickness and a narrower plate width than the outer legs 21a and 22a.

In addition, the outer legs 21a, 22a and the inner legs 21b, 22
The yoke that integrally connects the base of b is the outer leg 21a,
The inner leg 22a is narrower than the inner leg 21b and has a slightly wider plate width than the inner leg 22b.
Notches 21c and 22c are provided in the yoke portions corresponding to the left and right sides of 1b and 22b to form mounting positions for terminal pins, as will be described later.

Figures 8 and 9 show the transformer cores 21 and 2.
2 is a perspective view of a small transformer which is an embodiment of the present invention using a transformer according to the present invention, in which reference numeral 23 is a terminal pin, 24 is a bobbin, 25 is a coil, and 26 is an insulating tape wrapped around the outer circumferential surface of the coil. be.

As shown in the figure, the bobbin 24 has flanges at both ends of the cylindrical winding portion, and the surrounding portions of these flanges form the outer legs 21.
These flanges are located around the yoke including the notches 21c and 22c, and a terminal pin 23 is implanted therein, as shown in the figure. Further, the terminal pin 23 may be provided in a direction perpendicular to the inner legs 21b, 22b as shown in FIG.

As described above, the small transformer of the present invention has two transformer cores of the same shape, and the inner surface of the outer leg formed in a plate shape is curved to follow the outer peripheral surface of the coil, and is provided parallel to the outer leg. One surface of the plate-shaped inner leg facing the outer leg is formed to protrude almost parallel to the inner surface of the outer leg, making it smaller and flatter than conventional small transformers of this type without sacrificing operational performance. be able to.

Furthermore, in the present invention, a notch is provided in the core yoke, and the terminal pins are fixed to the bobbin flange around the yoke including the notch, so many terminal pins can be provided without enlarging the transformer shape. can. In addition, the plate width of the yoke is narrower than the width of the outer leg and slightly wider than the width of the inner leg, and cutouts are formed on both sides of the yoke, so the cross-sectional area that becomes the magnetic path of the connection between the inner leg and yoke is reduced. This makes it possible to reduce the plate thickness of the yoke, which is also advantageous in reducing the size of the transformer shape.

[Brief explanation of drawings]

Fig. 1a is an enlarged front view showing the iron core of a basic small transformer, Fig. 1b is a sectional view taken along the line O-O in Fig. 1a, and Figs. 2 to 5 explain the principle of the present invention. Figure 2a is a front view of the flattened transformer core, Figure 2b is Figure 2a
The above sectional view taken along line P-P, Figure 3a is a front view of the transformer core with expanded core width, Figure 3b is Figure 3a
A sectional view taken along the line Q-Q above, FIG. 4a is a front view of the transformer core with the core width expanded and the central leg flattened, FIG. 4b is a sectional view taken along the line R-R in FIG. 4a,
Figure 5a is an enlarged front view of an ideal transformer core.
Fig. 5b is a sectional view taken along line S-S in Fig. 5a, Fig. 6 is an enlarged front view of the transformer core used in the transformer of the present invention, and Fig. 7 is a sectional view taken along line V-V in Fig. 6. figure,
Fig. 8 is a perspective view of a small transformer showing an embodiment of the present invention, Fig. 9 is a sectional view taken along the line W-W in Fig. 8, and Fig. 10 shows a state where the terminal pins have been installed in different positions. FIG. 9 is a sectional view similar to FIG. 9; 21, 22...Transformer core, 21a, 22a
...Outer leg, 21b, 22b...Inner leg, 21c, 2
2c...Notch, 23...Terminal pin, 24...
Bobbin, 25...coil.

Claims (1)

[Claims] 1. Two legs made of ferrite material, including an inner leg to which the coil-wound body is attached, and an outer leg connected to the inner leg by a yoke and positioned outside the coil-wound body. A transformer core with legs is provided, the outer legs are formed in a plate shape, and the inner surface thereof is curved to follow the outer peripheral surface of the coil wrapping body, and the inner legs are formed in a plate shape parallel to the outer legs. form,
In addition, the inner leg has a larger wall thickness and a narrower plate width than the outer leg, and one side facing the outer leg is formed with a bulge parallel to the inner side of the outer leg, and the yoke has a plate width of the outer leg. It is a plate-shaped body that is narrower and slightly wider than the inner leg plate width and has notches formed on both sides in the plate width direction, and this yoke is configured to integrally connect the bases of the outer leg and the inner leg, and further, A bobbin has a winding cylinder portion into which the inner leg is inserted, and a bobbin having a rectangular collar integrally provided at both ends of the winding cylinder portion with a peripheral edge portion located within the inner surface of the outer leg. Insert the inner legs into the winding tube from both sides of the bobbin around which the wire is wound, and assemble the transformer core.
A small transformer in which the ends of the windings are fixed to terminal pins fixed to the collar around the yoke including the notch.