JP2003297643A - Transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the problem of individual components having irregularities in characteristics. <P>SOLUTION: A transformer is provided with a U-shaped core 1, in which both ends of a rod-like base part 11 are folded, up to a substantially right angle and are made first and second arm parts 12A and 12B respectively, and an I-shaped core 2 arranged between the first arm part 12A and the second arm part 12B. In the I-shaped core 2, notch parts 21A and 21B are formed at a corner part, where each edge part of the first arm part 12A and the second arm part 12B is positioned. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transformer having a core formed by combining a U core and an I core.

[0002]

2. Description of the Related Art A transformer having a core in which a U core and an I core are combined is often used as disclosed in, for example, Japanese Patent Laid-Open No. 2000-277342. The most popular transformer of this type is shown in plan view in FIG. 9A, and the core used in this transformer is shown in plan view in FIG. 9B.

The rod-shaped I-shaped core 81 is inserted into the bobbin 82, the rod-shaped base portion of the U-shaped core 83 is arranged in parallel with the I-shaped core 81, and the arm portion protruding from both ends of the rod-shaped base portion of the U-shaped core 83. The tip of 84 is positioned on both end faces of the I-shaped core.

A primary winding 85 and a secondary winding 86 are wound around the outer wall of the bobbin 82, and their ends are connected to any of the terminals 87 provided on the base of the bobbin 82.

[0005]

In the above-mentioned transformer, the I-shaped core 81 and the U-shaped core 83 are both ferrite cores and are made by firing at about 1000 ° C. 84 is deformed so as to warp outward toward the tip side. Therefore, when the tip of the arm portion 84 is positioned at both end surfaces of the I-shaped core, there is a problem that a gap is generated and a leakage magnetic flux is generated.

Further, the degree of warpage differs for each U-shaped core, which causes variations in the characteristics of parts. Further, there is a problem that the left and right arm portions 84 of one U-shaped core are deformed differently and it is difficult to adjust the gap.

The present invention has been made in order to solve the problems of the conventional transformer as described above, and an object thereof is to provide a transformer capable of suppressing the problem that the characteristics of individual parts vary.

[0008]

In the transformer according to the present invention, both ends of a rod-shaped base portion are bent substantially at right angles, and a U-shaped core having first and second arm portions, respectively, and the first In an I-shaped core arranged between the first arm and the second arm, the tip ends of the first arm and the second arm are positioned in the I-shaped core. A notch is formed at the corner.

A transformer according to the present invention has an I-shaped core having a substantially rectangular shape in plan view and having notches at a pair of corresponding longitudinal corners, and first ends from both ends of a rod-shaped base. , The second arm portion has an extended shape, and the first and second arm portions include a U-shaped core positioned in the cutout portion of the I-shaped core.

A transformer according to the present invention has an I-shaped core having a substantially rectangular shape in a plan view and having step portions at a pair of corresponding longitudinal corners, and a first end from each end of a rod-shaped base portion. , The second arm portion has an extended shape, and the first,
The second arm portion comprises a U-shaped core positioned on the stepped portion of the I-shaped core.

The transformer according to the present invention is characterized in that a magnetic gap is provided between the tip of each of the first and second arm portions of the U-shaped core and the I-shaped core.

In the transformer according to the present invention, a secondary winding is wound directly on the I-shaped core, and a bobbin is provided to cover the I-shaped core on which the secondary winding is wound. A primary winding is wound on the bobbin.

The transformer according to the present invention is characterized in that at least one of the primary winding and the secondary winding is formed by connecting a plurality of windings in parallel.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a transformer according to the present invention will be described below with reference to the accompanying drawings. In each drawing, the same constituent elements are designated by the same reference numerals, and duplicated description will be omitted. FIG. 1 shows a transformer according to the first embodiment, FIG. 2 is a perspective view of a core used in the transformer, and FIG. 3 is a plan view thereof. This core uses a U-shaped core 1 and an I-shaped core 2 in combination. The U core 1 has a shape in which both ends of a rod-shaped base portion 11 are bent substantially at right angles to form first and second arm portions 12A and 12B, respectively.

The I-core 2 has a rod shape arranged between the first arm 12A and the second arm 12B. I
The shaped core 2 includes a first arm 12A and a second arm 12A.
Notches 21A and 21B are formed at the corners where the respective tips of B are positioned. In other words, I
The shaped core 2 has a substantially rectangular shape in which the planar shape is long and slender, and has notches 21A and 21B at a pair of corresponding corners in the longitudinal direction.

In other words, the U-shaped core 1 has a rod-shaped base portion 11.
The first arm portion 12A and the second arm portion 12B respectively have a shape extending from both ends thereof. And the first
The arm portion 12A and the second arm portion 12B are positioned and brought into contact with the cutout portions 21A and 21B of the I-shaped core 2.

As is apparent from the comparison between FIG. 3 and FIG. 9, if the same magnetic path length is to be obtained, U in this embodiment will be used.
The first arm portion 12A of the core 1 and the second arm portion 12
It can be seen that the arm length of B can be made shorter than that of the conventional example. In other words, in the U-shaped core of the present embodiment, even if warping occurs during firing, it does not cause a large error due to the short length of the arm, and the gap between the cutout portions 21A and 21B of the I-shaped core 2 does not occur. It is possible to reduce the gap generated in the space much more than before.

The secondary winding 22 is directly wound around the I core 2 by a required number of turns. The I core 2 around which the secondary winding 22 is wound is inserted into the bobbin 3. 1 on the surface of bobbin 3
The next winding 23 is wound by a required number of turns. Terminals 31, 32, 33, and 34 are provided on the side of the bobbin 3 in the fixture, and the ends of the primary winding 23 and the secondary winding 22 are connected to the terminals 31, 32, 33. , 34.

The bobbin 3 in which the I core 2 is inserted and the winding is provided as described above has the first arm portion 12A and the second arm portion 12B with respect to the U core 1 fixed to the substrate 4.
Are placed so as to be positioned in the notches 21A and 21B of the I-shaped core 2 and fixed to the substrate 4.

According to such a transformer, the arm lengths of the first arm portion 12A and the second arm portion 12B are shorter than those of the conventional example, and depending on the warpage that occurs during firing, the I-shaped core A gap is unlikely to be formed between the two notches 21A and 21B, or the gap can be made much smaller than in the conventional case. Further, even when a magnetic gap is provided between the I-shaped core 2 and the cutouts 21A and 21B, the error due to each core can be suppressed.

Next, the transformer according to the second embodiment will be described. In the transformer according to the second embodiment, the U-shaped core 5 and the I-shaped core 6 shown in FIG. 4 are used as the core. The I-core 6 has a substantially rectangular shape in plan view, and has step portions 61A and 61B at a pair of corresponding corners in the longitudinal direction.

The U core 5 has a shape in which a first arm portion 52A and a second arm portion 52B respectively extend from both ends of a rod-shaped base portion 51, and the first arm portion 52A and the second arm portion 52B. Are positioned on the stepped portions 61A and 61B of the I-shaped core 6, respectively. In the first embodiment, the arm portions 12A and 12B have the same thickness as the base portion 11, whereas in the second embodiment, the first arm portion 52A and the second arm portions. The lower portion of the portion 52B is a space, and the lower portions of the stepped portions 61A and 61B of the I-shaped core 6 enter the lower space of the first arm portion 52A and the second arm portion 52B.

The other structure is the same as that of the first embodiment. That is, the secondary winding is directly wound around the I core 6 by the required number of turns. The I core 6 around which the secondary winding is wound is inserted into a bobbin (similar to the bobbin 3 in FIG. 1). The primary winding is wound on the surface of the bobbin by the required number of turns. On the side of the bobbin, a plurality of terminals are provided on the fixture similar to those shown in FIG. 1, and the ends of the primary winding and the ends of the secondary winding are connected to the above terminals. .

The bobbin in which the I-core 6 is inserted and the winding is provided as described above has a U-arm 5 fixed to a substrate similar to the substrate 4 of FIG. Second
Arm portion 52B of the I-shaped core 6 is a step portion 61A, 61B
Mounted on the substrate and fixed to the substrate.

Also in the transformer according to the second embodiment, the first arm portion 52A and the second arm portion 5 are also provided.
The arm length of 2B is shorter than that of the conventional example, and depending on the warp generated during firing, the stepped portions 61A, 61 of the I-shaped core 6 may be formed.
A gap between B and B is unlikely to occur, or it can be much smaller than before. Further, even when a magnetic gap is provided between the stepped portions 61A and 61B of the I-shaped core 6, an error due to each core can be suppressed to be small.

The magnetic gap is, for example, the first arm portion 5
It is provided between the lower portions of 2A and the second arm portion 52B and the surfaces of the step portions 61A and 61B of the I-shaped core 6, and can have the characteristics of a leakage flux type transformer.

Now, the primary winding and the secondary winding will be considered. In the following, the secondary winding 22 is taken as an example, but 1
The same applies to the next winding 23. 5 and 6
As shown in FIG. 1, one secondary winding 22 is wound around the I-shaped core 2 (6), for example, the winding start side end 22A is connected to the terminal 31, and the winding end side end 22B. Is connected to the terminal 34.

In the case of using one secondary winding 22 as described above, if the number of turns is increased, the length of the I-shaped core 2 (6) in the longitudinal direction is increased, and the transformer is enlarged. I have no choice. Further, when a large current needs to flow, the wire diameter of the secondary winding 22 needs to be increased in order to secure the current capacity, and the transformer is inevitably increased in size.

On the other hand, the following configuration is adopted. As shown in FIGS. 7 and 8, the I-shaped core 2 (6) has, for example, 3
The secondary windings 91, 92, 93 of the book are wound. The three secondary windings 91, 92, 93 have a circular cross section and have the same wire diameter, but the wire diameter is shorter than the wire diameter of the secondary winding 22 shown in FIG. 5 (for example, n 1/10). For example, the ends of the three secondary windings 91, 92, 93 on the winding start side are the terminals 3
1 and the end portion on the winding end side is connected to the terminal 34. That is, the secondary winding is a plurality of secondary windings 91, 92,
It is configured by connecting 93 in parallel.

With the above structure, the three secondary windings 91,
Assuming that the wire diameters of 92 and 93 are, for example, one-third of the wire diameter of the secondary winding 22 shown in FIG. 5, three secondary windings 91, 92 and 93 are one layer as shown in FIG. When they are stacked and wound one by one, the number of turns can be three times the number of turns in the example shown in FIG. That is, the number of turns can be increased without increasing the length of the I-shaped core 2 (6) in the longitudinal direction.

The wire diameter of the three secondary windings 91, 92, 93 is set to, for example, one third of the wire diameter of the secondary winding 22 shown in FIG. 5, and is the same as the example shown in FIG. To get the number of turns,
The length can be one third that of FIG. In such a case, since the diameter is 1/3, the increase in resistance is 9 times that in FIG. 5 in each winding, but since the three windings are connected in parallel, it remains only 3 times as a whole. Considering that the length can be reduced to one third, the resistance is the same as a whole. Thus, by connecting in parallel, it is possible to easily secure the current capacity when a large current needs to flow.

In the configuration examples of FIGS. 7 and 8, a plurality of windings are connected in parallel for the secondary winding.
A plurality of windings can be connected in parallel for at least one of the secondary winding and the secondary winding. In either case, a thin round wire is used as the winding wire without increasing the length of the I-shaped core 2 (6) in the longitudinal direction,
The number of turns can be set freely. In addition, it is possible to secure the current capacity by increasing the number of windings connected in parallel and substantially increasing the cross-sectional area of the windings.

[0033]

As described above, in the transformer of the present invention, the I-shaped core is provided with the notch or the stepped portion and the arm portion of the U-shaped core is positioned. It is possible to make the length shorter than that, and it is possible to reduce the influence of warpage or the like that occurs during manufacturing, and it is possible to suppress the problem that the characteristics of individual parts vary.

[Brief description of drawings]

FIG. 1 is a perspective view of a transformer according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a core used in the transformer according to the first embodiment of the present invention.

FIG. 3 is a plan view of a core used in the transformer according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a core used in the transformer according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view of essential parts showing an example in which a secondary winding is configured by one winding in the transformer according to the embodiment of the present invention.

FIG. 6 is a circuit configuration diagram showing an example in which a secondary winding is configured by one winding in the transformer according to the embodiment of the present invention.

FIG. 7 is a cross-sectional view of essential parts showing an example in which a secondary winding is configured by three windings in the transformer according to the embodiment of the present invention.

FIG. 8 is a circuit configuration diagram showing an example in which a secondary winding is configured by three windings in the transformer according to the embodiment of the present invention.

FIG. 9 is a plan view of a core used in a transformer according to a conventional example.

[Explanation of symbols]

1,5 U type core 2,6 I type core 3 bobbins 4 substrates 11,51 base 12A, 52A First arm portion 12B, 52B Second arm part 21A, 21B Notch 22 Secondary winding 23 Primary winding 61A, 61B step 91, 92, 93 Secondary winding

Claims (6)

[Claims] 1. A U-shaped core in which both ends of a rod-shaped base are bent substantially at right angles to form first and second arm portions, respectively, and between the first arm and the second arm. In the transformer having the I-shaped core arranged in, the notch is formed in the I-shaped core at a corner portion where the respective tip portions of the first arm and the second arm are positioned. A transformer that is characterized by being. 2. An I-shaped core having an elongated rectangular shape in plan view and having notches at a pair of longitudinally corresponding corners, and first and second arms from both ends of a rod-shaped base portion, respectively. And a U-shaped core positioned at the cutout portion of the I-shaped core, wherein the first and second arm portions have an extended shape. 3. An I-shaped core having a substantially rectangular shape in a plan view and having stepped portions at a pair of corresponding longitudinal corners, and first and second arms from both ends of a rod-shaped base portion, respectively. And a U-shaped core positioned at the step of the I-shaped core, wherein the first and second arm portions have an extended shape. 4. A magnetic gap is provided between the tip of each of the first and second arm portions of the U-shaped core and the I-shaped core. The transformer according to any one of items. 5. A secondary winding is wound directly on the I-shaped core, and a bobbin for covering the I-shaped core on which the secondary winding is wound is provided. The transformer according to any one of claims 1 to 4, wherein a secondary winding is wound. 6. The transformer according to claim 5, wherein at least one of the primary winding and the secondary winding is configured by connecting a plurality of windings in parallel.