JP2004303864A - Thin transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin transformer in which the degree of freedoms of designing a coil shape is high, the thickness can be reduced, the characteristics are stabilized, and which has a simplified structure at a low cost. <P>SOLUTION: The thin transformer includes a high voltage coil 1 in which a coil and an insulating layer are integrated and flattened, and low voltage coils 2, 3 obtained by punching a conductor sheet. Holes 1e, 1f or cutouts are provided at positions for avoiding the conductor of the coil in the insulating layer of the high voltage coil 1. Projections 2a, 2b, 3a, 3b are provided at parts corresponding to the holes 1e, 1f or the cutouts of the high voltage coil 1 at the low voltage coils 2, 3. The projections 2a, 3a and 2b, 3b are respectively engaged with the holes 1e and 1f or the cutouts to decide the relative positions of the high voltage coil 1 and the low voltage coils 2, 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thin transformer used for a switching power supply or the like, and particularly to a transformer suitable for a DC-DC converter of 1 kW to 2 kW output used for an automobile or the like.
[0002]
[Prior art]
As this type of transformer, there is a transformer described in Patent Document 1. This transformer has a spiral high voltage side coil coil, a U-shaped low voltage side coil, a thin insulating case having a shelf hole for accommodating these cases, and a base having terminals for connecting terminals of the coil. Consists of The base has a central cylindrical portion. The tubular portion is fitted into a hole provided vertically through the center of the case, and the center leg of the core is inserted into the tubular portion to insulate both coils from the core.
[0003]
[Patent Document 1]
Utility Model Registration No. 2579196.
[0004]
[Problems to be solved by the invention]
The transformer described in Patent Literature 1 has a problem that since the coil is inserted into the shelf hole of the case, the outer shape of the coil is limited to a rectangular parallelepiped, and the degree of freedom of the shape is small. In addition, since the strength of the mold for molding the case is limited, it is difficult to form the shelf hole long and thin, and it is difficult to reduce the thickness of the coil and thus the transformer. In addition, there is a problem that the capacitance and leakage inductance between the coils vary due to the play of the coils in the shelf hole in the case, and the characteristics are not stable. In addition, since the number of parts is large, there is a problem that assembly is difficult and cost is increased.
[0005]
In view of the above problems, an object of the present invention is to provide a thin transformer which has a high degree of freedom in coil shape design, can be made thinner, has stable characteristics, has a simplified structure, and is inexpensive. And
[0006]
[Means for Solving the Problems]
(1) A thin transformer according to the present invention is a thin transformer having a high-voltage side coil in which a coil and an insulating layer are integrated and planarized, and a low-voltage side coil formed by punching a conductive plate,
In the insulating layer of the high-voltage side coil, a hole or a notch is provided at a position avoiding the conductor of the coil,
The low-voltage side coil is provided with a projection at a portion corresponding to a hole or notch of the high-voltage side coil,
The relative position between the high voltage side coil and the low voltage side coil is determined by fitting the protrusion and the hole or notch.
[0007]
(2) In the thin transformer according to the present invention, the projection of the low-voltage side coil is provided by half punching.
[0008]
(3) In the thin transformer according to the present invention, at least a part of the inner peripheral portion and the outer peripheral portion of the high-voltage side coil adjacent to the core is at least partly inward of the inner peripheral portion and the outer peripheral portion of the low voltage side coil, respectively. By protruding outward, the insulation distance between the inner and outer peripheral portions of the low-voltage side coil and the core is maintained.
[0009]
(4) Further, the thin transformer of the present invention has a bobbin for vertically fixing a coil portion including the low-voltage side coil and the high-voltage side coil,
The bobbin has at least two flat pieces and locking pieces formed by being raised from the periphery thereof,
It is characterized in that the relative position of the coil portion with respect to the bobbin is fixed by being locked to the coil portion by the locking piece, and the insulation distance from the upper and lower core portions is maintained.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a sectional view showing an embodiment of a thin transformer according to the present invention, and FIG. 2 is an exploded perspective view of a coil unit. In FIGS. 1 and 2, reference numerals 1 and 1A denote high-voltage coils serving as primary coils of a transformer, and 2, 3 and 2A and 3A denote low-voltage coils.
[0011]
As shown in FIG. 3, the high voltage side coils 1 and 1A have coil patterns 5a and 5b made of a conductor such as copper on upper and lower surfaces of a substrate 4 such as a glass epoxy substrate. As shown in the plan perspective views of FIGS. 4A and 4B, these coil patterns 5a and 5b have a spiral shape. These coil patterns 5a and 5b are connected by a through hole 5c provided at the inner end. As shown in FIG. 3, the coil patterns 5a and 5b are covered with a resin insulating layer 6.
[0012]
The high voltage side coils 1 and 1A have outwardly extending terminal portions 1a, and the terminal portions 1a have terminals 1b and 1c communicating with the outer ends of the upper and lower coil patterns 5a and 5b, respectively. In the vicinity of the terminals 1b and 1c, the conductor is exposed for connection to an external circuit. In the center of the high voltage side coils 1 and 1A, there is a hole 1d into which the middle legs 7a and 8a of the E-shaped cores 7 and 8 are inserted. Further, positioning for fitting the projections 2a, 2b and 3a, 3b provided on the low-voltage side coils 2, 3 to diagonal portions around the high-voltage side coils 1, 1A where the conductor patterns 5a, 5b are not formed, respectively. Holes 1e and 1f are provided.
[0013]
In this embodiment, the low voltage side coils 2 and 3 are connected in parallel, and the low voltage side coils 2A and 3A are also connected in parallel. However, in order to prevent a short circuit between the low voltage side coils in the case of series connection, another low voltage side coil is used. Two diagonal portions also have positioning holes 1g and 1h for the low voltage side coil. Notches may be provided instead of part or all of the positioning holes 1e to 1h.
[0014]
The high voltage side coils 1 and 1A can be manufactured as follows. First, a hole of a through hole 5c is formed in a double-sided copper-clad printed circuit board, and then a through hole 5c for interlayer connection is formed by copper plating. Next, the coil patterns 5a and 5b are formed by etching. After that, insulating layers 6 are laminated on the upper and lower sides of the coil patterns 5a and 5b, a through hole for connection of the terminal portion 1a is formed, and an outer shape processing including drilling of positioning holes 1e, 1f, 1g and 1h is performed. Alternatively, after the coil patterns 5a and 5b are formed by etching, the outer shape is processed, and the entire coil portion is directly molded into an intended shape with an insulating material such as epoxy resin except for the terminal portion 1a.
[0015]
On the other hand, the low voltage side coils 2, 3 and 2A, 3A are produced by punching and bending a conductor plate such as a copper plate or an aluminum plate. The low-voltage side coils 2, 3, 2A, 3A of this embodiment are connected to both ends of each of the coils 2, 3, 2A, 3A, as shown in FIG. , 2d and 3d, 2f and 3f, 2g and 3g. Further, 2e, 3e and 2j, 3j are fixed to a metal base plate via an insulating layer, and have a role of releasing heat generated in the low voltage side coil and the high voltage side coil.
[0016]
FIG. 5 and FIG. 6 are views showing a combination structure of the low-voltage side coils 2 and 3 with respect to the high-voltage side coil 1 (same for 1A). As shown in FIG. 2, the low voltage side coils 2 and 3 have protrusions 2a and 2b and protrusions 3a and 3b at two diagonal points, respectively. These projections 2a, 3a, 2b, 3b are formed by half-punching in the same step as the punching of the conductor plate, and have a projection height of approximately half the thickness of the low-voltage side coils 2, 3 (2A, 3A). Having. The projections 2a, 3a are fitted into the positioning holes 1e of the high-voltage side coil 1 from above and below, and the projections 2b, 3b are fitted into the positioning holes 1f from above and below to position and join.
[0017]
In a state where the high-voltage side coil 1 (1A) and the low-voltage side coils 2, 3 (2A, 3A) are overlapped, as shown in FIG. 7A, the low-voltage side coils 2, 3 (2A, 3A) Terminals 2c and 3c, 2d and 3d (2f and 3f, 2g and 3g) overlap.
[0018]
The E-type cores 7, 8 are made of Mn-Zn ferrite. The cores 7, 8 are formed by inserting the middle feet 7a, 8a into the centers of the low-voltage coils 2, 3, 2A, 3A and the core insertion holes 1d of the high-voltage coils 1, 1A, and connecting the outer feet 7b, 8b to the high-voltage coils. 2. Combine them by making contact with the outer periphery of 2.
[0019]
In this transformer, the coil patterns 5a and 5b on the upper and lower surfaces of the high voltage side coils 1 and 1A each have 5 turns, for a total of 10 turns, the high voltage side coils 1 and 1A are connected in parallel with each other, and the low voltage side coils 2 and 3 and 2A are connected to each other. 3A are respectively connected in parallel, these are used as terminals 2c, 3c and 2f, 3f center taps, and can be used as a 10: 1: 1 transformer. That is, one terminal 2d, 3d of the low voltage side coil 2, 3, 2A, 3A is connected to one diode of the secondary side circuit, and the other 2c, 3c is connected to the metal base plate, and serves as a center tap. One terminal 2g, 3g of the low voltage side coil 2A, 3A is connected to the other diode of the secondary side circuit, and the other terminal 2f, 3f becomes a center tap like the terminals 2c, 3c.
[0020]
In this transformer, when the thickness of the coil patterns 5a and 5b is set to, for example, 270 μm, the thickness of the high voltage side coils 1 and 1A is about 2 mm (the thickness of the substrate 4 is about 0.5 mm, the coil pattern is 0.27 mm × 2 = 0). .52 mm, and the thickness of the insulating layer 6 is about 0.5 mm × 2 = 1 mm, which is about 2 mm in total). In addition, since the thickness of the low-voltage coils 2, 3, 2A, and 3A is about 1.5 mm, the total thickness of the high-voltage coils 1, 1A and the low-voltage coils 2, 3, 2A, and 3A is about 10 mm in total. No problem.
[0021]
1 and 7, reference numeral 9 denotes a bobbin made of an insulating resin, and reference numeral 11 (12) denotes a coil portion including a high voltage side coil 1 (1A) and low voltage side coils 2, 3 (2A, 3A). The bobbin 9 is provided with a hole 9a in the center of the flat plate portion 9x for inserting the middle feet 7a, 8a of the cores 7, 8, and an inner cylindrical portion 9b provided to protrude up and down around the insertion hole 9a. And an outer cylindrical portion 9c protruding up and down on the outer peripheral portion, and locking pieces 9d of the coil portions 11 and 12 provided at diagonal positions on the upper and lower surfaces of the bobbin 9, respectively.
[0022]
As shown in FIGS. 7A and 7B, the coil units 11 and 12 are connected by the bobbin 9. This coupling is performed as shown in FIG. As shown in FIG. 8, at least a portion of the outer peripheral portion of the high-voltage side coil 1 (1A also) protrudes outward from the outer peripheral portions of the low-voltage side coils 2 and 3. At least a part of the inner peripheral portion of the high-voltage side coil 1 projects inward from the inner peripheral portions of the low-voltage side coils 2 and 3. As shown in FIG. 8 (A), the coil part 11 is fixed to the bobbin 9 by fitting the inner peripheral wall of the low-voltage side coil of the coil part 11 to the inner cylindrical part 9b of the bobbin 9 and the outer peripheral part of the bobbin 9 9 and is turned in the direction indicated by an arrow R to lock the locking portions 2h and 2i of the low-voltage side coil 2 with the bobbin 9 as shown in FIG. It is locked to the piece 9d and fixed with a structure that prevents floating. The coil section 12 is similarly configured and is fixed to the bobbin 9.
[0023]
Next, as shown in FIGS. 7B and 7C, the cores 7 and 8 are attached to the coil portions 11 and 12 connected by the bobbin 9. Numerals 13 and 14 are terminals to be inserted into the holes of the terminals 1b and 1c and fixed to connect the high voltage side coils 1 and 1A to the outside.
[0024]
If the transformer is configured in this manner, the insulation distances G1, G2 between the middle feet 7a, 8a and the outer feet 7b, 8b of the cores 7, 8 and the inner circumference and the outer circumference of the low voltage side coils 2, 3, 2A, 3A. Thus, the vertical insulation distance G3 (see FIG. 1) can be reliably ensured.
[0025]
Further, the high voltage side coil 1 (1A) and the low voltage side coils 2, 3 (2A, 3A) are directly connected via the insulating layer 6, and the positioning is performed by fitting the projections 2a, 3a with the holes 1e, 1f. As a result, positional accuracy is high, and variations in capacitance and leakage inductance are reduced. Further, since the position is fixed also in the thickness direction by the bobbin 9, variations in capacitance and inductance are further reduced. Therefore, a transformer having stable characteristics can be provided. Further, since the high-voltage side coil 1 (1A) and the low-voltage side coils 2, 3 (2A, 3A) are directly connected via the insulating layer 6, the thickness can be reduced and the number of parts is small and the configuration is small. Since it is simplified and the number of assembling steps is reduced, the cost can be reduced. In addition, since it is not necessary to house the coil in the case, the degree of freedom in designing the coil shape is improved.
[0026]
Further, the projections 2a, 3a may be formed by cutting and raising, bending, or the like. However, if these are formed by half punching, the same die and the same process as the outer shape punching process of the low voltage side coils 2, 3, 2A, 3A are used. In this case, the projections 2a, 2b, 3a, 3b can be formed. Therefore, without increasing the number of steps, it is possible to obtain an object having high relative position accuracy and dimensional accuracy with respect to the external shape, and to prevent rattling. In the above-described embodiment, the holes 1e and 1f of the high-voltage side coils 1 and 1A are formed as the through holes.
[0027]
In the above-described embodiment, the transformer is configured using two high-voltage side coils and four low-voltage side coils. However, various changes can be made to these numbers according to a required current capacity. For example, a configuration in which one high-voltage side coil and one low-voltage side coil are superimposed, a configuration in which one high-voltage side coil and two low-voltage side coils are superimposed, and the like.
[0028]
【The invention's effect】
The transformer of the present invention determines the relative position between the high voltage side coil and the low voltage side coil by fitting the projection of the low voltage side coil and the hole or notch of the high voltage side coil, so that the positional accuracy is high, the capacitance and A transformer with small variations in leakage inductance and stable characteristics can be provided. Further, since the high-voltage side coil and the low-voltage side coil are directly connected via the insulating layer, the thickness can be reduced. Further, since the number of parts is small and the configuration is simplified and the number of assembly steps is reduced, the cost of the transformer can be reduced. In addition, since it is not necessary to house the coil in the case, the degree of freedom in designing the coil shape is improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing one embodiment of a thin transformer according to the present invention.
FIG. 2 is an exploded perspective view of a coil unit according to the embodiment.
FIG. 3 is a sectional view of a high-voltage side coil according to the present embodiment.
FIGS. 4A and 4B are perspective plan views showing coil patterns on an upper surface and a lower surface of a high-voltage side coil according to the present embodiment, respectively.
FIG. 5 is a side view showing a relative positioning structure between a high-voltage side coil and a low-voltage side coil according to the present embodiment in a state before assembly.
FIG. 6 is a side view showing a state after assembly in FIG. 5;
FIGS. 7A to 7C are perspective views showing an assembling process of the embodiment of FIG. 1;
FIGS. 8A and 8B are partial cross-sectional plan views showing a process of assembling the bobbin in the embodiment of FIG. 1;
[Explanation of symbols]
1, 1A: high voltage side coil, 2 and 2A: low voltage side coil, 3 and 3A: low voltage side coil, 4: substrate, 5a, 5b: coil pattern, 6: insulating layer, 7, 8: core, 9: bobbin, 11, 12: coil part, 13, 14: terminal

Claims (4)

A high-voltage side coil in which the coil and the insulating layer are integrated and planarized, and a thin transformer having a low-voltage side coil punched out of a conductive plate,
In the insulating layer of the high-voltage side coil, a hole or a notch is provided at a position avoiding the conductor of the coil,
The low-voltage side coil is provided with a projection at a portion corresponding to a hole or notch of the high-voltage side coil,
A low-profile transformer wherein the relative positions of the high-voltage side coil and the low-voltage side coil are determined by fitting the protrusion and the hole or notch. The thin transformer according to claim 1,
The projection of the low-voltage side coil is provided by half punching. The thin transformer according to claim 1 or 2,
At least a part of the inner peripheral portion and the outer peripheral portion of the high-voltage side coil adjacent to the core protrude inward and outward from the inner peripheral portion and the outer peripheral portion of the low-voltage side coil, respectively. A thin transformer characterized by maintaining an insulation distance between an inner peripheral portion and an outer peripheral portion and a core. The thin transformer according to any one of claims 1 to 3,
A bobbin for fixing a coil portion including the low voltage side coil and the high voltage side coil in a vertical direction,
The bobbin has at least two flat pieces and at least two locking pieces formed by being raised from the periphery thereof,
A thin transformer, which is locked to the coil portion by the locking piece to fix a relative position of the coil portion with respect to the bobbin and to maintain an insulation distance from upper and lower core portions.

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