CN117751415A

CN117751415A - Transformer

Info

Publication number: CN117751415A
Application number: CN202280050358.8A
Authority: CN
Inventors: 西山睦夫; 大休寺新
Original assignee: Mitsumi Electric Co Ltd
Current assignee: Mitsumi Electric Co Ltd
Priority date: 2021-07-30
Filing date: 2022-03-28
Publication date: 2024-03-22

Abstract

The present invention relates to transformers. The core (11) has a hollow portion (11 a) extending in the front-rear direction. The conductive wire (12) is wound around the core (11). The first core and the second core are formed of a material containing a magnetic body. The first magnetic core has: a first inner part (131 a) extending from one end of the core part (11) in the front-rear direction into the hollow part (11 a); and a first outer part (131 b) which is opposite to the conductive wire (12) from at least the upper direction and the left-right direction. The second magnetic core has: a second inner portion (132 a) extending from the other end portion of the core portion (11) in the front-rear direction into the hollow portion (11 a); and a second outer part (132 b) which faces the conductive line (12) from at least the upper direction and the left-right direction. The front end of the first inner side portion (131 a) and the front end of the second inner side portion (132 a) are opposed in the front-rear direction. The diameter of the front end of the first inner side portion (131 a) is different from the diameter of the front end of the second inner side portion (132 a).

Description

Transformer

Technical Field

The present disclosure relates to a transformer.

Background

Japanese patent application laid-open No. 2019-153757 discloses a transformer provided with a core, a conductive wire, a first magnetic core, a second magnetic core, and a shielding member. The core has a hollow portion extending in a first direction. The conductive wire is wound around the core. The first core and the second core are each formed of a material containing a magnetic body. The first magnetic core has: a first inner portion extending from one end portion of the core portion in the first direction into the hollow portion; and a first outer portion opposed to the conductive line from a second direction orthogonal to the first direction. The second magnetic core has: a second inner portion extending from the other end portion of the core portion in the first direction into the hollow portion; and a second outer portion opposed to the conductive line from the second direction. The shielding member is formed by bending a conductive plate material. The shielding member has a portion facing the conductive line from the second direction and a portion facing the conductive line from a third direction orthogonal to the first direction and the second direction.

Disclosure of Invention

Problems to be solved by the invention

There is a need to improve the stability of the inductance of a transformer (first need).

There is a need to improve the noise resistance of transformers (second need).

Means for solving the problems

One embodiment of the present disclosure provided to address the first need described above is a transformer including:

a core portion having a hollow portion extending in a first direction;

a conductive wire wound around the core;

a first magnetic core having: a first inner portion extending from one end portion of the core portion in the first direction into the hollow portion; and a first outer portion facing the conductive line from at least a second direction orthogonal to the first direction and a third direction orthogonal to the first direction and the second direction, and formed of a material including a magnetic body; and

a second magnetic core having: a second inner portion extending from the other end portion of the core portion in the first direction into the hollow portion; and a second outer portion facing the conductive line from the second direction and the third direction and formed of a material including a magnetic body,

the front end of the first inner side portion and the front end of the second inner side portion are opposed in the first direction,

a maximum dimension of a front end of the first inner side portion is different from a maximum dimension of a front end of the second inner side portion in at least one of the second direction and the third direction.

The maximum dimension of the distal end of the first inner portion and the maximum dimension of the distal end of the second inner portion facing each other in the first direction are intentionally made different in at least one of the second direction and the third direction, so that even when the first magnetic core and the second magnetic core deviate from a desired positional relationship, a change in the cross-sectional area of the region through which the magnetic flux can pass in the first direction can be suppressed. Therefore, the stability of the inductance of the transformer with respect to various positional deviation factors can be improved.

One embodiment of the present disclosure provided to address the second need is a transformer including:

a core portion having a hollow portion extending in a first direction;

a conductive wire wound around the core;

a first magnetic core having: a first inner portion extending from one end portion of the core portion in the first direction into the hollow portion; and a first outer portion facing the conductive line from at least a second direction orthogonal to the first direction and a third direction orthogonal to the first direction and the second direction, and formed of a material including a magnetic body;

a second magnetic core having: a second inner portion extending from the other end portion of the core portion in the first direction into the hollow portion; and a second outer portion facing the conductive line from the second direction and the third direction and formed of a material including a magnetic body; and

and a shield case having a slit-free box shape surrounding the first and second magnetic cores from the first, second, and third directions, and formed of a material having conductivity.

The shield case is provided to suppress electromotive force that may be generated in the conductive wire due to a magnetic field that is noise coming from the outside of the transformer. In order to improve the noise resistance of the transformer, a countermeasure for preparing a thicker shield case is generally taken.

The inventors of the present application focused on the behavior of eddy currents flowing on the surface of the shield case due to an external magnetic field. The eddy current generates demagnetization, and the effect of reducing the influence of an external magnetic field is achieved. Thus, the following concept is obtained: if a structure that hardly blocks the flow of eddy current can be provided, the influence of external magnetic field can be effectively reduced even without increasing the thickness of the shield case. Moreover, it was found that: in a shield case formed by bending a part of a plate material, obstruction of the flow of eddy current is generated in a slit inevitably formed between adjacent bent plate materials.

As described above, the shield case has a box-like shape without a slit, thereby forming continuous conductive surfaces facing the first direction, the second direction, and the third direction. Thus, eddy current generated by the external magnetic field can smoothly flow on the conductive surface. Therefore, the size of the transformer can be suppressed from increasing with an increase in the thickness of the shield case, and the noise resistance can be improved.

Drawings

Fig. 1 is an exploded perspective view illustrating an external appearance of a transformer of an embodiment.

Fig. 2 illustrates an external appearance of a transformer of an embodiment.

Fig. 3 illustrates an external appearance of the transformer of fig. 1 as viewed from below.

Fig. 4 illustrates a cross section of the transformer as seen from the arrow direction along the line IV-IV in fig. 3.

Fig. 5 illustrates a cross section of the transformer as seen from the arrow direction along the line V-V in fig. 3.

Fig. 6 illustrates an external appearance of the shield case.

Fig. 7 shows another example of the structure of the shield case.

Fig. 8 illustrates an external appearance of a transformer provided with the shield case of fig. 7.

Fig. 9 is a perspective view illustrating an external appearance of the transformer of fig. 1 to 6.

Fig. 10 is a front view illustrating an exterior design of the transformer of fig. 9.

Fig. 11 is a rear view illustrating an exterior design of the transformer of fig. 9.

Fig. 12 is a plan view illustrating an exterior design of the transformer of fig. 9.

Fig. 13 is a bottom view illustrating an exterior design of the transformer of fig. 9.

Fig. 14 is a left side view illustrating an exterior design of the transformer of fig. 9.

Fig. 15 is a right side view illustrating an exterior design of the transformer of fig. 9.

Fig. 16 is a perspective view illustrating an exterior design of the transformer of fig. 7 and 8.

Fig. 17 is a front view illustrating an exterior design of the transformer of fig. 16.

Fig. 18 is a rear view illustrating an exterior design of the transformer of fig. 16.

Fig. 19 is a plan view illustrating an exterior design of the transformer of fig. 16.

Fig. 20 is a bottom view illustrating an exterior design of the transformer of fig. 16.

Fig. 21 is a left side view illustrating an exterior design of the transformer of fig. 16.

Fig. 22 is a right side view illustrating an exterior design of the transformer of fig. 16.

Fig. 23 shows another example of a cross section of the transformer as seen from the arrow direction along the line IV-IV in fig. 3.

Fig. 24 is a diagram illustrating the influence of the positional deviation of the core in the transformer of the comparative example.

Fig. 25 is a diagram illustrating the influence of the positional deviation of the core in the transformer of fig. 23.

Fig. 26 is a diagram showing a change rate of inductance due to positional displacement of the core.

Detailed Description

Hereinafter, examples of the embodiments will be described in detail with reference to the drawings. In the drawings, arrow F indicates the forward direction of the illustrated construction. Arrow B indicates the rearward direction of the illustrated construction. Arrow U indicates the upward direction of the illustrated construction. Arrow D indicates the downward direction of the illustrated construction. Arrow R indicates the right direction of the illustrated construction. Arrow L indicates the left direction of the illustrated construction. The expressions relating to these directions are used for convenience of description, and are not limited to the posture and direction of the illustrated structure in the actual use state.

The term "front-rear direction" used in the present specification means a direction along the above-described front direction and rear direction. The term "vertical direction" used in the present specification means a direction along the above-described upward and downward directions. The term "left-right direction" used in the present specification means a direction along the above-described left direction and right direction.

The expression "extending in the front-rear direction" as used in the present specification includes extending obliquely with respect to the front-rear direction, and means extending at an inclination closer to the front-rear direction than the up-down direction and the left-right direction.

The expression "extending in the up-down direction" as used in the present specification includes extending obliquely with respect to the up-down direction, and means extending at an inclination closer to the up-down direction than the front-back direction and the left-right direction.

The expression "extending in the left-right direction" as used in the present specification includes extending obliquely with respect to the left-right direction, and means extending at an inclination closer to the left-right direction than the front-rear direction and the up-down direction.

Fig. 1 is an exploded perspective view illustrating an external appearance of a transformer 10 of an embodiment. Fig. 2 illustrates an external appearance of the transformer 10 viewed from the upper right front direction. Fig. 3 illustrates an external appearance of the transformer 10 as viewed from below. Fig. 4 illustrates a cross-section of the transformer 10 as viewed from the arrow direction along the line IV-IV in fig. 3. Fig. 5 illustrates a cross section of the transformer 10 as viewed from the arrow direction along the line V-V in fig. 3.

As illustrated in fig. 1, 4, and 5, the transformer 10 includes a core 11 and a conductive wire 12. The core 11 has a hollow portion 11a extending in the front-rear direction. The conductive wire 12 is wound around the core 11 to form a coil. The front-rear direction is an example of the first direction.

The transformer 10 includes a first core 131. The first core 131 is formed of a material containing a magnetic substance. As an example of this material, ferrite is given.

The first magnetic core 131 has a first inner portion 131a and a first outer portion 131b. The first inner portion 131a extends from the front end portion of the core 11 into the hollow portion 11a. The first outer portion 131b is opposed to the conductive line 12 from the upper direction and the left-right direction. The tip end portion is an example of one end portion of the core 11 in the first direction. The upward direction is an example of the second direction. The left-right direction is an example of the third direction.

The transformer 10 includes a second core 132. The second core 132 is formed of a material containing a magnetic substance. As an example of this material, ferrite is given.

The second magnetic core 132 has a second inner portion 132a and a second outer portion 132b. The second inner portion 132a extends from the rear end portion of the core 11 into the hollow portion 11a. The second outer portion 132b is opposed to the conductive line 12 from the upper direction and the left-right direction. The rear end portion is an example of the other end portion of the core 11 in the first direction.

As illustrated in fig. 1 to 5, the transformer 10 includes a shield case 14. The shield case 14 is formed of a material having conductivity. As illustrated in fig. 2 and 6, the shield case 14 has a box shape without a slit. As illustrated in fig. 4 and 5, the shield case 14 surrounds the first magnetic core 131 and the second magnetic core 132 from the front-rear direction, the upward direction, and the left-right direction.

The shield case 14 is provided to suppress electromotive force that may be generated in the conductive wire 12 due to a magnetic field that is noise coming from the outside of the transformer 10. In order to improve the noise resistance of the transformer, a countermeasure for preparing a thicker shield case is generally taken.

The inventors of the present application focused on the behavior of eddy currents flowing on the surface of the shield case due to an external magnetic field. The eddy current generates demagnetization, and the effect of reducing the influence of an external magnetic field is achieved. Thus, the following concept is obtained: if a structure that hardly blocks the flow of eddy current can be provided, the influence of an external magnetic field can be effectively reduced even without increasing the thickness of the shield case. Moreover, it was found that: in a shield case formed by bending a part of a plate material, obstruction of the flow of eddy current is generated in a slit inevitably formed between adjacent bent plate materials.

As described above, the shield case 14 of the present embodiment has a box shape without a slit, thereby forming a continuous conductive surface facing in the upward direction, the front-rear direction, and the left-right direction. Thus, eddy current generated by the external magnetic field can smoothly flow on the conductive surface. Therefore, the size of the transformer can be suppressed from increasing with an increase in the thickness of the shield case, and the noise resistance can be improved.

The shield case 14 of the present embodiment may be a single piece formed by drawing a plate material. The term "monolithic part" as used in this specification refers to a part having a monolithic structure. The term "monolithic part" is used to distinguish components that are integrated by combining multiple parts by various methods. Examples of the various methods include adhesion, bonding, welding, engagement, fitting, screwing, and the like.

In this case, not only the bending step but also the joint can be removed from the shield case 14. A discontinuous structure such as a seam may be one cause of blocking the flow of eddy current. That is, the shield case 14 formed by drawing can promote smooth flow of eddy current.

As illustrated in fig. 4 to 6, the shield case 14 has a left wall 14a, a right wall 14b, a front wall 14c, a rear wall 14d, and an upper wall 14e. The upper wall 14e is seamlessly connected to the left wall 14a, the right wall 14b, the front wall 14c, and the rear wall 14d by the corner portions 14f, respectively. The corner 14f extends in the front-rear direction or the left-right direction. The left wall 14a, the right wall 14b, the front wall 14c, and the rear wall 14d are connected to the adjacent walls by the corner portions 14g, respectively, without seams. The corner 14g extends in the up-down direction.

The inventors have also found that: in the case where the shield case has a corner portion formed by a boundary where flat side surfaces share a straight line with each other, there is a tendency that the flow of eddy current is hindered at the boundary. In the present embodiment, the corner portions 14f and 14g of the shield case 14 are curved surfaces, respectively. The flow of eddy current can be promoted by reducing the straight line boundary from the shield case 14. The shield case 14 can be formed by the drawing process described above, and the bent corner can be easily formed.

As illustrated in fig. 4, the transformer 10 includes a base 15 and a plurality of terminals 16. The base 15 is formed of a material having electrical insulation. The plurality of terminals 16 are each formed of a material having conductivity.

The plurality of terminals 16 are integrally formed with the base 15, respectively. Each of the plurality of terminals 16 has a coil terminal 161 and a mounting terminal 162. An end portion (not shown) of the conductive wire 12 wound around the core 11 is electrically connected to the coil terminal 161. The mounting terminals 162 are electrically connected to circuit elements formed on the circuit board when the transformer 10 is mounted on the circuit board. Thereby, the conductive line 12 is electrically connected to the circuit element on the circuit board.

As illustrated in fig. 1, the transformer 10 includes a restriction member 17. The restriction member 17 is formed of a material having conductivity. The restriction member 17 is preferably formed of the same material as the shield case 14.

As illustrated in fig. 4, the restriction member 17 has a first portion 17a. The first portion 17a is disposed so as to face the conductive line 12 from below. The lower direction is an example of the fourth direction. When the transformer 10 is mounted on the circuit board, the first portion 17a is disposed between the conductive wire 12 and the circuit board.

As illustrated in fig. 5, the restriction member 17 extends in the left-right direction. The restriction member 17 has a second portion 17b and a third portion 17c. The second portion 17b extends continuously from the left end of the first portion 17a, and is joined to the left wall 14a of the shield case 14. The third portion 17c extends continuously from the right end of the first portion 17a, and is joined to the right wall 14b of the shield case 14. The coupling with the shield case 14 may be performed by various methods such as adhesion, joining, welding, engagement, fitting, screwing, and the like. Thereby, the displacement of the shield case 14 in the upward direction with respect to the base 15 is restricted.

As illustrated in fig. 6, the shield case 14 has a box shape that opens in a downward direction. Therefore, the shield case 14 cannot cover the conductive wire 12 from below. However, according to the above-described configuration, a portion surrounding the conductive wire 12 from the radially outer side of the core 11 can be ensured in the transformer 10. That is, the restricting member 17 can be made to have an effect of improving shielding performance against noise from the lower direction, and the restricting member 17 restricts the position of the shield case 14 with respect to the base 15.

As illustrated in fig. 7, the shield case 14 and the restricting member 17 may be integrally formed. The restricting member 17 of this example includes a first restricting piece 17d and a second restricting piece 17e. The first restriction piece 17d extends downward from the left wall 14a of the shield case 14. The second restricting piece 17e extends downward from the right wall 14b of the shield case 14.

In this case, as illustrated in fig. 8, the tip of the first restricting piece 17d is coupled with the tip of the second restricting piece 17e below the core 11, thereby restricting the displacement of the shield case 14 in the upward direction with respect to the base 15. The joint portion between the first restriction piece 17d and the second restriction piece 17e is disposed so as to face the conductive wire 12 from below.

With this configuration, the number of parts can be reduced, and the process of fixing the shield case 14 to the base 15 can be simplified.

In addition, one of the first restriction piece 17d and the second restriction piece 17e may be omitted. For example, when the second regulating piece 17e is omitted, the first regulating piece 17d is configured to have a portion disposed so as to face the conductive wire 12 from below the base 15 and a distal end portion coupled to the left wall 14a of the shield case 14. That is, the first restriction piece 17d can be configured to have the following length: extends from the right wall 14b of the shield case 14 to the left wall 14a of the shield case 14 via the lower side of the base 15, and can restrict the upward displacement of the shield case 14 with respect to the base 15.

As illustrated in fig. 4, the front wall 14c and the rear wall 14d of the shield case 14 face the first core 131 and the second core 132 from the front-rear direction. The front wall 14c and the rear wall 14d are respectively in contact with the base 15. The front wall 14c and the rear wall 14d are examples of the first wall portion, respectively.

The upper wall 14e of the shield case 14 faces the first core 131 and the second core 132 from above with a gap therebetween. The upper wall 14e is an example of the second wall portion.

With the above-described configuration, the shield case 14 is positioned in the up-down direction with respect to the base 15 by the contact of the front wall 14c and the rear wall 14d with respect to the base 15. In other words, the upper wall 14e is prevented from contacting the first core 131 and the second core 132, and thus a gap is prevented from being formed between the lower end of the shield case 14 and the base 15. Therefore, invasion of external noise from below can be suppressed.

As illustrated in fig. 4 and 5, the first outer portion 131b of the first magnetic core 131 has a rounded corner 131c opposed to the corner 14f of the shield case 14. Likewise, the second outer portion 132b of the second magnetic core 132 has a rounded corner 132c opposed to the corner 14f of the shield case 14.

With this configuration, interference between the corners of the first core 131 and the second core 132 and the inner wall surface of the shield case 14 can be easily avoided. Therefore, occurrence of a situation in which the shield case 14 is displaced from a predetermined position due to interference and noise resistance performance is lowered can be suppressed. Further, the necessity of increasing the size of the shield case 14 to avoid interference is reduced, and the size of the transformer 10 can be suppressed from increasing. In particular, in the case where the shield case 14 is formed by drawing, the corner 14f has a curved shape, and this effect is more remarkable. That is, in this case, the rounded portions 131c and 132c include portions having a curved shape along the corner portions 14f, respectively.

The first outer portion 131b of the first magnetic core 131 has a rounded corner 131d opposed to the core 11. The rounded portion 131d includes a portion having a shape corresponding to the outer peripheral surface of the core 11 in the radial direction. In other words, the rounded portions 131d are formed so as to minimize the gap with the core 11. Likewise, the second outer portion 132b of the second magnetic core 132 has a rounded portion 132d opposed to the core 11. The rounded portion 132d includes a portion having a shape corresponding to the outer peripheral surface of the core 11 in the radial direction. In other words, the rounded portions 132d are formed so as to minimize the gap with the core 11.

According to such a configuration, it is possible to suppress a decrease in wall thickness that occurs in the first magnetic core 131 with the formation of a portion surrounding a part of the core 11. This suppresses a decrease in inductance and a decrease in rigidity of the first magnetic core 131. Similarly, the wall thickness reduction in the second magnetic core 132 associated with the formation of the portion surrounding the core 11 can be suppressed. This can suppress a decrease in inductance and a decrease in rigidity of the second core 132.

The above-described embodiments are merely examples for easy understanding of the present invention. The configuration of the above-described embodiment can be modified as appropriate without departing from the gist of the present invention.

In the above-described embodiment, the left wall 14a, the right wall 14b, the front wall 14c, the rear wall 14d, and the upper wall 14e of the shield case 14 have flat portions, respectively. If the shield case 14 has a box-like shape without a slit, at least one of the left wall 14a, the right wall 14b, the front wall 14c, the rear wall 14d, and the upper wall 14e may have a shape that does not have a flat portion.

As long as the shield case 14 having a box shape without a slit can be provided, a manufacturing method other than drawing may be employed. As an example, the shield case 14 may be formed by bending a plate material and joining end surfaces to each other. The corner 14f and the corner 14g having curved shapes may be formed by cutting or the like. As another example, the shield case 14 of copper alloy, aluminum alloy, or the like may be formed by a die casting method. Since this manufacturing method is excellent in productivity, by forming the shield case 14 in the same shape as that formed by drawing, it is possible to secure desired characteristics and suppress an increase in manufacturing cost.

In the above-described embodiment, the first inner portion 131a of the first magnetic core 131 and the second inner portion 132a of the second magnetic core 132 have circular cross-sectional shapes, respectively. However, the cross-sectional shape of each of the first and second inner side portions 131a and 132a can be appropriately determined. In this case, the first inner portion 131a and the second inner portion 132a may have different maximum dimensions in at least one of the vertical direction and the horizontal direction.

The design of the transformer according to the embodiment described with reference to fig. 1 to 6 is illustrated in fig. 9 to 15. Fig. 9 is a perspective view. Fig. 10 is a front view. Fig. 11 is a rear view. Fig. 12 is a top view. Fig. 13 is a bottom view. Fig. 14 is a left side view. Fig. 15 is a right side view.

The appearance of the transformer of the embodiment example to be described with reference to fig. 7 and 8 is illustrated in fig. 16 to 22. Fig. 16 is a perspective view. Fig. 17 is a front view. Fig. 18 is a rear view. Fig. 19 is a top view. Fig. 20 is a bottom view. Fig. 21 is a left side view. Fig. 22 is a right side view.

As illustrated in fig. 23, the diameter of the front end of the first inner side portion 131a may also be different from the diameter of the front end of the second inner side portion 132 a. The diameter is an example of the maximum dimension of each of the second direction and the third direction.

Effects obtained by such a configuration will be described with reference to fig. 24 to 26. Fig. 24 shows a first inner side portion 131a 'of the first magnetic core and a second inner side portion 132a' of the second magnetic core of the comparative example. The diameter of the front end of the first inner side portion 131a 'coincides with the diameter of the front end of the second inner side portion 132a'.

In such a configuration, when the first magnetic core and the second magnetic core deviate from a desired positional relationship, the cross-sectional area a of the region through which the magnetic flux passes changes from a predetermined value. Therefore, the value of the inductance also changes.

On the other hand, as illustrated in fig. 25, by intentionally making the diameter of the front end of the first inner portion 131a facing in the front-rear direction different from the diameter of the front end of the second inner portion 132a, even when the first magnetic core 131 and the second magnetic core 132 deviate from a desired positional relationship, a change in the cross-sectional area a of the region through which the magnetic flux can pass in the front-rear direction can be suppressed. Therefore, the stability of the inductance of the transformer 10 against various positional deviation factors can be improved.

In fig. 26, a plurality of black circles connected by a broken line represent actual measurement values of the relationship between the amount of shift in the radial direction from a predetermined positional relationship and the rate of change in inductance without shift in the first inner portion 131a 'and the second inner portion 132a' in the transformer of the comparative example. In addition, the diameter of the first inner portion 131a 'and the diameter of the second inner portion 132a' are each 1.8mm.

In the drawing, a plurality of white circles connected by solid lines represent actual measurement values of the relationship between the amount of shift in the radial direction from a predetermined positional relationship and the rate of change in inductance without shift in the first inner portion 131a and the second inner portion 132a in the transformer 10 of the present embodiment. In addition, the diameter of the first inner portion 131a is 1.8mm, and the diameter of the second inner portion 132a is 1.6mm.

As is clear from the comparison result, the stability of the inductance of the transformer 10 with respect to the cause of the positional shift of the first core 131 and the second core 132 is improved.

As contents constituting a part of the present disclosure, contents of japanese patent applications 2021-125405 proposed by 2021, 7 and 30, 2021-125406 proposed by 2021, 7 and 30, and 2021-210500 proposed by 2021, 12 and 24 are cited.

Claims

1. A transformer, characterized by comprising:

a core portion having a hollow portion extending in a first direction;

a conductive wire wound around the core;

a first magnetic core having: a first inner portion extending from one end portion of the core portion in the first direction into the hollow portion; and a first outer portion facing the conductive wire from at least a second direction orthogonal to the first direction and a third direction orthogonal to the first direction and the second direction, the first core being formed of a material including a magnetic body; and

a second magnetic core having: a second inner portion extending from the other end portion of the core portion in the first direction into the hollow portion; and a second outer portion facing the conductive wire from the second direction and the third direction, the second core being formed of a material including a magnetic body,

2. The transformer according to claim 1, wherein the transformer comprises a transformer,

the shielding case is formed of a material having conductivity, and has a box shape having no slit and surrounding the first core and the second core from the first direction, the second direction, and the third direction.

3. A transformer according to claim 2, wherein,

the shield shell is formed by drawing processing.

4. A transformer, characterized by comprising:

a core portion having a hollow portion extending in a first direction;

a conductive wire wound around the core;

a first magnetic core having: a first inner portion extending from one end portion of the core portion in the first direction into the hollow portion; and a first outer portion facing the conductive wire from at least a second direction orthogonal to the first direction and a third direction orthogonal to the first direction and the second direction, the first core being formed of a material including a magnetic body;

a second magnetic core having: a second inner portion extending from the other end portion of the core portion in the first direction into the hollow portion; and a second outer portion facing the conductive wire from the second direction and the third direction, the second core being formed of a material including a magnetic body; and

5. The transformer according to claim 4, wherein the transformer comprises a transformer,

the shield shell is formed by drawing processing.

6. A transformer according to claim 4 or 5, wherein,

the first outer portion of the first magnetic core and the second outer portion of the second magnetic core each have a rounded corner portion opposed to an inner wall surface of the shield case.

7. The transformer according to claim 6, wherein the transformer comprises a transformer,

the first outer portion of the first magnetic core and the second outer portion of the second magnetic core each have a rounded corner portion opposite the core portion.