transformer

Abstract

To improve noise resistance performance of a transformer.SOLUTION: A core part 11 includes a hollow part 11a extending in a forward / backward direction. A conductive wire 12 is wound about the core part 11. A first core and a second core are formed of a material including a magnetic material. The first core includes: a first inner portion 131a extending into the hollow part 11a from one end t in the forward / backward direction of the core part 11; and a first outer portion 131b opposite to the conductive wire 12 from at least an upper direction and a right and left direction. The second core includes: a second inner portion 132a extended into the hollow part 11a from the other end part in the forward / backward direction of the core part 11; and a second outer portion 132b that is opposite to the conductive wire 12 from at least the upper direction and the right and left direction. A shield case 14 is formed by a material having a conductivity, and includes a box type shape without a slit surrounding the first and second cores from the forward / backward direction, the upper direction, and the right and left direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a transformer. [Background technology]

[0002] Patent Document 1 discloses a transformer including a core, a conductive wire, a first core, a second 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 and second cores are each formed of a material containing a magnetic substance. The first core has a first inner portion extending from one end of the core in the first direction into the hollow portion and a first outer portion facing the conductive wire from a second direction perpendicular to the first direction. The second core has a second inner portion extending from the other end of the core in the first direction into the hollow portion and a second outer portion facing the conductive wire from the second direction. The shielding member is formed by bending a conductive plate material. The shielding member has a portion facing the conductive wire from the second direction and a portion facing the conductive wire from a third direction perpendicular to the first and second directions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-153757 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to improve the noise resistance performance of a transformer. [Means for solving the problem]

[0005] In order to achieve the above object, one aspect of the present invention is a transformer, a core having a hollow portion extending in a first direction; a conductive wire wound around the core; a first core made of a material including a magnetic substance, the first core having a first inner portion extending into the hollow portion from one end of the core portion in the first direction, and a first outer portion facing the conductive wire at least in a second direction perpendicular to the first direction and a third direction perpendicular to the first direction and the second direction; a second core having a second inner portion extending into the hollow portion from the other end of the core portion in the first direction and a second outer portion facing the conductive wire in the second direction and the third direction, the second core being made of a material containing a magnetic substance; a shield case having a slitless box shape that surrounds the first core and the second core from the first direction, the second direction, and the third direction, and that is made of a conductive material; It is equipped with:

[0006] The shielding case is provided to suppress the electromotive force that can be generated in the conductive wires due to the magnetic field as noise coming from outside the transformer. In order to improve the noise resistance performance of the transformer, a measure of providing a thicker shielding case is generally taken.

[0007] The inventors of the present application focused on the behavior of eddy currents that flow on the surface of a shielding case due to an external magnetic field. Eddy currents generate a demagnetizing field, which has the effect of reducing the effects of the external magnetic field. Therefore, they came up with the idea that if a structure could be provided that is less likely to impede the flow of eddy currents, the effects of the external magnetic field could be efficiently reduced without increasing the thickness of the shielding case. They then discovered that the obstruction of the flow of eddy currents occurs in the slits that are inevitably formed between adjacent folded plates in shielding cases, which are generally formed by bending portions of plate material.

[0008] As described above, the slitless box-shaped shielding case forms a continuous conductive surface facing the first, second, and third directions. This allows eddy currents generated by an external magnetic field to flow smoothly along the conductive surface. This improves noise resistance while preventing the transformer from becoming larger due to an increase in the thickness of the shielding case. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view illustrating an external appearance of a transformer according to an embodiment. [Figure 2] 1 illustrates an external view of a transformer according to an embodiment. [Figure 3] This shows an example of the appearance of the transformer in Figure 1 as seen from below. [Figure 4] 4 illustrates a cross section of the transformer taken along line IV-IV in FIG. 3 as viewed in the direction of the arrows. [Figure 5] 4 illustrates a cross section of the transformer as viewed from the direction of the arrow along line VV in FIG. 3. [Figure 6] An example of the appearance of the shield case is shown. [Figure 7] 10 shows another example of the configuration of the shield case. [Figure 8] 8 illustrates an example of the appearance of a transformer equipped with the shielding case of FIG. 7. [Figure 9] FIG. 7 is a perspective view illustrating the design of the transformer according to FIGS. 1 to 6. [Figure 10] FIG. 11 is a front view illustrating the design of the transformer of FIG. 10. [Figure 11] FIG. 11 is a rear view illustrating the design of the transformer of FIG. 10. [Figure 12] 11 is a plan view illustrating the design of the transformer of FIG. 10. FIG. [Figure 13] 11 is a bottom view illustrating the design of the transformer of FIG. 10. [Figure 14] FIG. 11 is a left side view illustrating the design of the transformer of FIG. 10. [Figure 15]FIG. 11 is a right side view illustrating the design of the transformer of FIG. 10. [Figure 16] FIG. 9 is a perspective view illustrating the design of the transformer according to FIGS. 7 and 8. [Figure 17] FIG. 17 is a front view illustrating the design of the transformer of FIG. 16. [Figure 18] FIG. 17 is a rear view illustrating the design of the transformer of FIG. 16. [Figure 19] 17 is a plan view illustrating the design of the transformer of FIG. 16. FIG. [Figure 20] 17 is a bottom view illustrating the design of the transformer of FIG. 16. [Figure 21] FIG. 17 is a left side view illustrating the design of the transformer of FIG. 16. [Figure 22] FIG. 17 is a right side view illustrating the design of the transformer of FIG. 16. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0023] An example embodiment will be described in detail below with reference to the accompanying drawings. In the accompanying drawings, arrow F indicates the forward direction of the illustrated structure. Arrow B indicates the rearward direction of the illustrated structure. Arrow U indicates the upward direction of the illustrated structure. Arrow D indicates the downward direction of the illustrated structure. Arrow R indicates the rightward direction of the illustrated structure. Arrow L indicates the leftward direction of the illustrated structure. These directional expressions are used for convenience of explanation and do not limit the posture or direction of the illustrated structure in actual use.

[0011] The term "front-rear direction" used in this specification means a direction along the aforementioned front and rear directions. The term "up-down direction" used in this specification means a direction along the aforementioned top and bottom directions. The term "left-right direction" used in this specification means a direction along the aforementioned left and right directions.

[0012] The expression "extending in the front-to-rear direction" used in this specification includes extending at an angle relative to the front-to-rear direction, and means extending at an angle closer to the front-to-rear direction than the up-down and left-to-right directions.

[0013] The expression "extending in the vertical direction" used in this specification includes extending at an angle relative to the vertical direction, and means extending at an angle closer to the vertical direction than the front-to-back and left-to-right directions.

[0014] The expression "extending in the left-right direction" used in this specification includes extending at an angle relative to the left-right direction, and means extending at an angle closer to the left-right direction than the front-back and up-down directions.

[0015] FIG. 1 is an exploded perspective view illustrating the appearance of a transformer 10 according to one embodiment. FIG. 2 illustrates the appearance of the transformer 10 as viewed from the upper right front direction. FIG. 3 illustrates the appearance of the transformer 10 as viewed from below. FIG. 4 illustrates a cross section of the transformer 10 as viewed from the direction of the arrows along line IV-IV in FIG. 3. FIG. 5 illustrates a cross section of the transformer 10 as viewed from the direction of the arrows along line VV in FIG. 3.

[0016] As illustrated in Figures 1, 4, and 5, a 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 a first direction.

[0017] The transformer 10 includes a first core 131. The first core 131 is made of a material containing a magnetic substance, such as ferrite.

[0018] The first core 131 has a first inner portion 131a and a first outer portion 131b. The first inner portion 131a extends from the front end of the core 11 into the hollow portion 11a. The first outer portion 131b faces the conductive wire 12 from the upward and left-right directions. The front end is an example of one end 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.

[0019] The transformer 10 includes a second core 132. The second core 132 is made of a material containing a magnetic substance, such as ferrite.

[0020] The second core 132 has a second inner portion 132a and a second outer portion 132b. The second inner portion 132a extends from the rear end of the core 11 into the hollow portion 11a. The second outer portion 132b faces the conductive wire 12 from above and from the left and right directions. The rear end is an example of the other end of the core 11 in the first direction.

[0021] As illustrated in FIGS. 1 to 5, the transformer 10 includes a shielding case 14. The shielding case 14 is made of a conductive material. As illustrated in FIGS. 2 and 6, the shielding case 14 has a slitless box shape. As illustrated in FIGS. 4 and 5, the shielding case 14 surrounds the first core 131 and the second core 132 in the front-rear, top, and left-right directions.

[0022] The shielding case 14 is provided to suppress electromotive forces that may be generated in the conductive wires 12 due to magnetic fields acting as noise coming from outside the transformer 10. In order to improve the noise resistance of the transformer, a measure of providing a thicker shielding case is generally taken.

[0023] The inventors of the present application focused on the behavior of eddy currents that flow on the surface of a shielding case due to an external magnetic field. Eddy currents generate a demagnetizing field, which has the effect of reducing the effects of the external magnetic field. Therefore, they came up with the idea that if a structure could be provided that is less likely to impede the flow of eddy currents, the effects of the external magnetic field could be efficiently reduced without increasing the thickness of the shielding case. They then discovered that the obstruction of the flow of eddy currents occurs in the slits that are inevitably formed between adjacent folded plates in shielding cases, which are generally formed by bending portions of plate material.

[0024] As described above, the shielding case 14 according to this embodiment has a slitless box shape, which forms continuous conductive surfaces facing upward, forward, backward, and left and right. This allows eddy currents generated by an external magnetic field to flow smoothly along these conductive surfaces. This allows for improved noise resistance while suppressing the increase in size of the transformer due to an increase in the thickness of the shielding case.

[0025] The shield case 14 according to this embodiment may be a one-piece part formed by drawing a sheet material. As used herein, the term "one-piece part" refers to a part having a monolithic structure. The term "one-piece part" is used to distinguish it from a part that is integrated by joining multiple parts together by various methods. Examples of the various methods include adhesive bonding, joining, welding, engagement, fitting, and screwing.

[0026] In this case, not only can the bending process be omitted, but it is also possible to eliminate seams from shielding case 14. A structure with discontinuities such as seams can be a factor in obstructing the flow of eddy currents. In other words, shielding case 14 formed by drawing can promote the smooth flow of eddy currents.

[0027] As illustrated in Figures 4 to 6, the shielding case 14 has a left wall 14a, a right wall 14b, a front wall 14c, a rear wall 14d, and a top wall 14e. The top wall 14e is seamlessly connected to each of the left wall 14a, the right wall 14b, the front wall 14c, and the rear wall 14d by corners 14f. The corners 14f extend in the front-rear or left-right direction. In addition, each of the left wall 14a, the right wall 14b, the front wall 14c, and the rear wall 14d is seamlessly connected to the adjacent wall by corners 14g. The corners 14g extend in the up-down direction.

[0028] The inventors of the present application have also found that when a shielding case has corners formed by flat side surfaces sharing a linear boundary, the flow of eddy currents tends to be obstructed at the boundary. In this embodiment, corners 14f and 14g of shielding case 14 are each curved. Removing linear boundaries from shielding case 14 can promote the flow of eddy currents. Forming shielding case 14 using the drawing process described above makes it easy to form curved corners.

[0029] 4, the transformer 10 includes a base 15 and a plurality of terminals 16. The base 15 is made of an electrically insulating material. Each of the plurality of terminals 16 is made of a conductive material.

[0030] Each of the plurality of terminals 16 is molded integrally with the base 15. Each of the plurality of terminals 16 has a coil terminal 161 and a mounting terminal 162. An end (not shown) of the conductive wire 12 wound around the core 11 is electrically connected to the coil terminal 161. When the transformer 10 is mounted on a circuit board, the mounting terminal 162 is electrically connected to a circuit element formed on the circuit board. This electrically connects the conductive wire 12 to the circuit element on the circuit board.

[0031] 1, the transformer 10 includes a restricting member 17. The restricting member 17 is made of a conductive material. Preferably, the restricting member 17 is made of the same material as the shielding case 14.

[0032] 4, the restricting member 17 has a first portion 17a. The first portion 17a is disposed so as to face the conductive wire 12 from below. The downward direction is an example of a fourth direction. When the transformer 10 is mounted on a circuit board, the first portion 17a is disposed between the conductive wire 12 and the circuit board.

[0033] As illustrated in FIG. 5 , the restricting member 17 extends in the left-right direction. The restricting 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 connected to the left wall 14a of the shielding case 14. The third portion 17c extends continuously from the right end of the first portion 17a and is connected to the right wall 14b of the shielding case 14. The connection to the shielding case 14 can be achieved by various techniques, such as adhesive bonding, joining, welding, engagement, fitting, and screwing. This restricts the shielding case 14 from being displaced upward relative to the base 15.

[0034] 6, shielding case 14 has a box-like shape that opens downward. Therefore, shielding case 14 cannot cover conductor wires 12 from below. However, with the above-described configuration, a portion of transformer 10 where conductor wires 12 are surrounded from the radially outer side of core 11 can be secured. In other words, restricting member 17, which restricts the position of shielding case 14 relative to base 15, can also serve to improve shielding against noise from below.

[0035] 7, the shield case 14 and the restricting member 17 may be integrally molded. The restricting member 17 according to this example includes a first restricting piece 17d and a second restricting piece 17e. The first restricting 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.

[0036] 8, the tip of first restricting piece 17d and the tip of second restricting piece 17e are joined below core 11, thereby restricting upward displacement of shielding case 14 relative to base 15. The joint between first restricting piece 17d and second restricting piece 17e is positioned so as to face conductive wire 12 from below.

[0037] With this configuration, the number of parts can be reduced, and the process of fixing shield case 14 to base 15 can be simplified.

[0038] Note that one of first and second control pieces 17d and 17e may be omitted. For example, if second control piece 17e is omitted, first control piece 17d may be configured to have a portion that is positioned so as to face conductive wire 12 from below base 15, and a tip portion that is coupled to left wall 14a of shielding case 14. In other words, first control piece 17d may be configured to extend from right wall 14b of shielding case 14, via below base 15, to left wall 14a of shielding case 14, and have a length that can restrict upward displacement of shielding case 14 relative to base 15.

[0039] 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 in the front-to-rear direction. Each of the front wall 14c and the rear wall 14d is in contact with the base 15. Each of the front wall 14c and the rear wall 14d is an example of a first wall portion.

[0040] 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 a second wall portion.

[0041] According to the above-described configuration, shield case 14 is positioned relative to base 15 in the up-down direction by contact of front wall 14c and rear wall 14d with base 15. In other words, it is possible to prevent a gap from being generated between the bottom end of shield case 14 and base 15, which would otherwise occur if top wall 14e came into contact with first core 131 and second core 132 first. This makes it possible to suppress the intrusion of external noise from below.

[0042] 4 and 5, the first outer portion 131b of the first core 131 has rounded corners 131c facing the corners 14f of the shield case 14. Similarly, the second outer portion 132b of the second core 132 has rounded corners 132c facing the corners 14f of the shield case 14.

[0043] This configuration makes it easier to avoid interference between the corners of the first core 131 and the second core 132 and the inner wall surface of the shield case 14. This prevents interference from causing the shield case 14 to shift from its predetermined position, thereby reducing the noise resistance. Additionally, there is less need to increase the dimensions of the shield case 14 to avoid interference, which helps prevent the transformer 10 from becoming larger. This effect is particularly pronounced when the shield case 14 is formed by drawing, since the corners 14f have a curved shape. That is, in this case, each of the rounded corners 131c and 132c includes a portion curved along the corner 14f.

[0044] The first outer portion 131b of the first core 131 has a rounded corner 131d facing the core portion 11. The rounded corner 131d includes a portion having a shape corresponding to the outer peripheral surface of the core portion 11 in the radial direction. In other words, the rounded corner 131d is formed so as to minimize the gap that occurs between the core portion 11. Similarly, the second outer portion 132b of the second core 132 has a rounded corner 132d facing the core portion 11. The rounded corner 132d includes a portion having a shape corresponding to the outer peripheral surface of the core portion 11 in the radial direction. In other words, the rounded corner 132d is formed so as to minimize the gap that occurs between the core portion 11.

[0045] With this configuration, it is possible to suppress a reduction in thickness of first core 131 that accompanies the formation of a portion that surrounds a portion of core 11. This makes it possible to suppress a decrease in inductance and a decrease in rigidity of first core 131. Similarly, it is possible to suppress a reduction in thickness of second core 132 that accompanies the formation of a portion that surrounds a portion of core 11. This makes it possible to suppress a decrease in inductance and a decrease in rigidity of second core 132.

[0046] The above-described embodiments are merely examples for facilitating understanding of the present invention, and the configurations according to the above-described embodiments may be appropriately modified or improved without departing from the spirit and scope of the present invention.

[0047] In the above embodiment, each of the left wall 14a, the right wall 14b, the front wall 14c, the rear wall 14d, and the top wall 14e of the shielding case 14 has a flat portion. If the shielding case 14 has a slitless box shape, at least one of the left wall 14a, the right wall 14b, the front wall 14c, the rear wall 14d, and the top wall 14e may have a shape that does not have a flat portion.

[0048] As long as it is possible to provide a shielding case 14 having a slitless box-like shape, manufacturing methods other than drawing can be used. As one example, the shielding case 14 may be formed by bending a plate material and joining the end faces together. The curved corners 14f and 14g may be formed by cutting or the like. As another example, the shielding case 14 may be formed from a copper alloy, an aluminum alloy, or the like by a die-casting method. This manufacturing method has excellent productivity, and by forming the shielding case 14 into a shape similar to that of the shielding case 14 formed by drawing, it is possible to suppress increases in manufacturing costs while ensuring the desired characteristics.

[0049] The design of the transformer according to the embodiment described with reference to FIGS. 1 to 6 is illustrated in FIGS. 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 plan view, FIG. 13 is a bottom view, FIG. 14 is a left side view, and FIG. 15 is a right side view.

[0050] The design of the transformer according to the embodiment described with reference to FIGS. 7 and 8 is illustrated in FIGS. 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 plan view, FIG. 20 is a bottom view, FIG. 21 is a left side view, and FIG. 22 is a right side view. [Explanation of symbols]

[0051] 10: Transformer, 11: Core part, 11a: Hollow part, 12: Conductive wire, 131: First core, 131a: First inner part, 131b: First outer part, 131c: Round corner part, 131d: Round corner part, 132: Second core, 132a: Second inner part, 132b: Second outer part , 132c: Round corner, 132d: Round corner, 14: Shield case, 14c: Front wall, 14d: Rear wall, 14e: Top wall, 14f: Corner, 14g: Corner, 15: Base, 16: Terminal, 17: Regulation member, 17a: First part, 17d: First regulation piece, 17e: Second regulation piece

Claims

1. a core having a hollow portion extending in a first direction; a conductive wire wound around the core; a first core made of a material including a magnetic substance, the first core having a first inner portion extending into the hollow portion from one end of the core portion in the first direction, and a first outer portion facing the conductive wire at least in a second direction perpendicular to the first direction and a third direction perpendicular to the first direction and the second direction; a second core having a second inner portion extending into the hollow portion from the other end of the core portion in the first direction and a second outer portion facing the conductive wire in the second direction and the third direction, the second core being made of a material containing a magnetic substance; a shield case having a slitless box shape that surrounds the first core and the second core from the first direction, the second direction, and the third direction, and that is made of a conductive material; It is equipped with the first outer portion of the first core and the second outer portion of the second core each have a rounded corner portion facing an inner wall surface of the shield case when viewed from the second direction, the inner wall surface of the shield case facing the rounded corner portion has a curved shape that follows the rounded corner portion, The rounded corner portion and the inner wall surface face each other via a gap. transformer.

2. The shield case is formed by drawing. The transformer according to claim 1 .

3. The first outer portion of the first core and the second outer portion of the second core each have a rounded corner portion facing the core portion. The transformer according to claim 1 .

4. A base supporting a conductive terminal to which an end of the conductive wire is electrically connected; a restricting member that is made of a conductive material, has a portion that faces the conductive wires from a fourth direction opposite to the second direction, and restricts displacement of the shielding case relative to the base in the second direction; Equipped with A transformer according to any one of claims 1 to 3.

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