JP2001167939A - Pot rivet type core surface mounted choke coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pot rivet type core surface mounted choke coil which has an excellent direct current superposing characteristic and a simple form construction. SOLUTION: A pot rivet type core mounted choke coil has a pot type core 10 comprising a top wall 101 and a sidewall 103 which is united with the top wall, a rivet type core 20 comprising a bottom plate 201 and a magnet core part 204 which is provided erect in the center and united with a bottom plate, a space of a magnetic route formed by an upper terminal surface of the magnet core 204 nearly contacting and facing the lower surface of the top wall 101 of the pot type core 10 and a pot rivet type core, which is bonded and fixed with the pot type core 10 and the rivet type core 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pot rivet type core surface mount choke coil, and more particularly, to a pot rivet type core obtained by combining a pot type core and a rivet type core as a coil core and having a superimposed DC current characteristic. An improved pot rivet core surface mount choke coil.

[0002]

2. Description of the Related Art A conventional example of a surface mount choke coil is shown in FIG.
This will be described with reference to FIG. FIG. 3A is a perspective view of a surface mount choke coil, and FIG.
It is a figure which shows the height direction cross section along line bb 'in (a). FIG. 4 is an exploded perspective view of the surface mount choke coil of FIG. 3 and 4, 1 is a ring core, 2 is a drum core, 3 is a winding, and 4 is a terminal. These ring core 1 and drum core 2 are made of ferrite which is an electrically insulating material. A pair of flat portions 12 facing each other is formed on a part of the side surface of the ring core 1. A notch 11 is formed at the lower end of the arcuate surface portion 13 which is opposed to the pair of flat surface portions 12 and is adjacent to the pair of flat surface portions 12.

The drum core 2 includes a pair of flanges 21 and a winding core 22 which is integrally connected to the two flanges 21 to connect the two. A pair of flat portions 211 facing each other is formed in a part of the both flange portions 21. The coil 3 is wound around the core portion 22 of the drum core 2 to form the coil 30. The terminal 4 has a cut-and-raised piece formed as a terminal core fixing portion 41 in the center thereof. One end of the terminal 4 is slightly bent in the same plane from the terminal body to form a caraque solder portion 42, and the other end is bent at a right angle to form a rising portion 43.

The above-described ring core 1, drum core 2, winding 3, and terminal 4 are manufactured and prepared. Here, FIG.
Referring to (b), the terminal 4 is bonded and fixed to the surface of one flange 21 of the drum core 2 via a terminal core fixing portion 41 with a thermosetting adhesive such as epoxy resin. In this case, the rising portions 43 of the terminals 4 are opposed to the flat portions 211 of the both flange portions 21 of the drum core 2 and are jointed and fixed in parallel with each other. Next, referring to FIG. 4 (c), the winding 3 is wound around the core 22 of the drum core 2 configured as shown in FIG. 4 (b). Then, both ends of the winding 3 are lapped to the lump solder 42 of the terminal 4. Carrage solder part 42 of terminal 4
In the state where the winding ends of the windings 3 are luggaged, the reflow soldering is performed on the luggage solder portion 42 to completely electrically and mechanically connect the terminals 4 and the windings 3.

[0005] The ring core 1 is fitted to the drum core 2, the windings 3, and the terminals 4 assembled as described above.
When fitting the ring core 1, the notch 11 at the lower end of the arcuate surface portion 13 of the ring core 1 is opposed to the carrage solder portion 42, and the lower end of the flat portion 12 is parallel to each other so as to correspond to the rising portion 43 of the terminal 4. I do. The soldering portion 42 of the terminal 4 is bent after soldering,
The notch 11 is formed by the bent carrage solder portion 42.
Constitute an accommodation area. Since the drum core 2 including the winding 3 is covered with the heat-shrinkable tube and accommodated in the ring core 1, the gap 5 is substantially filled with the heat-shrinkable tube.

[0006]

The surface mounted choke coil using the drum core 2 and the ring core 1 has a limitation in electrical characteristics, that is, superposition characteristics. The choke coil is operated and used in a state where a DC bias voltage is applied when the choke coil is operated. However, since the core is made of a magnetic material, it naturally approaches magnetic saturation as the DC bias voltage increases, and the inductance of the coil decreases. Therefore, the DC bias voltage applied to the choke coil cannot be increased without limit, and there is a certain limit.

[0007] The assembly of the surface mount choke coil described above requires a large number of working steps and a long time required for all manufacturing steps. That is, the terminal 4 is bonded and fixed to the surface of the one flange 21 of the drum core 2 via the terminal core fixing portion 41 with a thermosetting adhesive such as epoxy resin. Then
The winding 3 is wound around the core 22 of the drum core 2. Then, both ends of the winding 3 are lapped to the lump solder portion 42 of the terminal 4. In a state in which the winding end of the winding 3 is lugged to the lump solder 42 of the terminal 4, reflow soldering is performed on the luggage solder 42 to electromechanically connect the terminal 4 and the winding 3. The ring core 1 is fitted to the drum core 2, the winding 3, and the terminal 4 assembled as described above. The lump solder portion 42 of the terminal 4 is bent after soldering. The above six steps are required.

[0008] In addition, if a surface-mounted choke coil is manufactured by purchasing an existing rectangular wire and using it, the cost of the surface-mounted choke coil is increased. The present invention provides a pot rivet type surface mount choke coil which solves the above-mentioned problem.

[0009]

Means for Solving the Problems Claim 1: A pot type core 10 comprising a top wall 101 and a side wall 103 integrally formed with the top wall, and a bottom plate 201 and a bottom plate are integrally formed at the center thereof. A rivet-type core 20 having a magnetic core portion 204 that is erected is provided. The upper surface of the magnetic core portion 204 is brought into close proximity to the lower surface of the top wall 101 of the pot-type core 10 to form a gap in a magnetic path. A pot rivet-type core surface-mount choke coil in which the mold core 10 and the rivet-type core 20 were joined and fixed was formed.

[0010] Claim 2: A through hole 102 in the center.
Is formed, the pot-shaped core 10 includes a top wall 101 and a side wall 103 integrally formed with the top wall 101, and a bottom plate 201 and a magnetic core portion erected integrally with the bottom plate 201 at the center thereof. A pot rivet-type core surface-mounted choke coil having the rivet-type core 20 composed of the core 204 and having the pot-type core 10 and the rivet-type core 20 joined and fixed in a state where the magnetic core portion 204 is inserted into the through-hole 102 was formed.

[0011] Claim 3: Claims 1 and 2
In the pot rivet type core surface mounted choke coil described in any one of the above, the terminal 4 is fixed to the bottom plate 201, and the coil terminal portion 31 of the coil 3 is connected to the terminal 4. Configured. Claim 4: In the pot rivet type surface mount choke coil according to claim 3, the terminal 4 has a U-shaped cross-section mounting portion 44 and a coil connection portion 45 integrally formed from the mounting portion 44. Bottom plate 2
01 is formed on the surface of the terminal mounting surface 203 with a step lower by the thickness of the terminal 4.
A pot rivet-type core surface-mounted choke coil mounted and fixed on the reference numeral 03 was constructed.

In a fifth aspect of the present invention, in the pot rivet type core surface mount choke coil according to any one of the first to fourth aspects, the coil 3 is formed by winding an electric wire having a round or square cross section. A pot rivet-type core surface mount choke coil was formed. Claim 6: In the pot rivet type core surface mount choke coil according to any one of claims 1 to 4, the coil 3 is formed by spirally winding a rectangular copper wire formed by cutting an electrolytic copper plate. A pot rivet-type core surface-mounted choke coil was formed by winding a rectangular wire formed by deforming into a shape and applying an insulating material coating on the surface.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the embodiment, in which (a) is a perspective view of a pot-shaped core, (b) is a perspective view of a rectangular coil, and (c) is a perspective view of a rivet-type core and terminals. 2A and 2B are views showing the assembled choke coil, FIG. 2A is a perspective view of the choke coil, and FIG. 2B is a view showing a longitudinal section taken along a line bb ′ in FIG.
1 and 2, members common to those in FIGS. 3 and 4 are denoted by common reference numerals.

Reference numeral 10 denotes a pot type core made of ferrite. 101 indicates a top wall of the square pot-shaped core 10,
A through hole 102 is formed at the center. 103
Is a side wall of the pot-shaped core 10. A notch 104 is formed at the lower part of the corner where the adjacent side walls 103 intersect. The pot-type core 10 fills a metal mold with ferrite fine powder, pressurizes and molds. The pressure-molded body of the pot-shaped core 10 made of the fine ferrite powder is then fired at a high temperature to form the ferrite pot-shaped core 10.

Reference numeral 3 denotes a coil. In the embodiment of FIG. 1, the coil 3 is formed by winding a rectangular electric wire. The flat wire coil 3 is formed by spirally deforming a flat copper wire. Reference numeral 31 denotes a coil terminal unit. The rectangular electric wire coil 3 is formed by spirally deforming a rectangular copper wire formed by cutting an extremely thin thickness of an electrolytic copper plate and applying an insulating material coating on the surface. Here, the flat wire coil 3 is formed by winding about four turns. The coil 3 can be generally formed by winding a round or square electric wire in cross section.

Reference numeral 4 denotes a terminal. The terminal 4 includes a mounting section 44 having a U-shaped cross section, a coil connecting section 45 integrally formed from the mounting section 44, and a locking projection 46 protruding from the upper surface of the coil connecting section 45. Reference numeral 20 denotes a rivet-type core made of ferrite. The rivet-type core 20 includes a square bottom plate 201 and a magnetic core portion 204 erected integrally with the bottom plate 201 at the center thereof. 202
Is a fitting thin portion formed at an intermediate portion between two opposing sides of the bottom plate 201, and a mounting portion 44 of the terminal 4 having a U-shaped cross section is fitted and fixed. Reference numeral 203 denotes a terminal mounting surface, which is an area provided with a step lower than the surface of the bottom plate 201 by the thickness corresponding to the thickness of the terminal 4.

The rivet core 20 also fills a metal mold with ferrite fine powder and pressurizes to mold the magnetic core 204 and the bottom plate 201 integrally. The rivet-type core press-formed body made of the ferrite fine powder is then fired at a high temperature to form the rivet-type core 20. The order of assembling the choke coil using the above components will be described. A pot type core 10, a rectangular wire coil 3, a terminal 4, and a rivet type core 20 are prepared.

Terminal mounting surface 20 of rivet type core 20
The terminal 4 is fitted and fixed to the fitting 3 and the fitting thin portion 202.
The rectangular electric wire coil 3 is fitted to the magnetic core portion 204 of the rivet type core 20. Coil end 3 of rectangular wire coil 3
1 is soldered to the coil connection portion 45 of the terminal 4. At this time, the coil connecting portion 45 of the terminal 4 is temporarily engaged with a locking projection 46 formed on the upper surface of the coil connecting portion 45. An epoxy-based synthetic resin adhesive is applied to the peripheral edge of the opening of the pot type core 10 and the surface of the bottom plate 201 of the rivet type core 20. With the magnetic core portion 204 of the rivet-type core 20 inserted through the through hole 102 of the pot-type core 10, the two are joined and fixed.

Thus, the assembly of the choke coil is completed. The size of the pot rivet type core surface mount choke coil is, for example, the height of the side wall 103 is 3.8 mm, the height of the notch 104 is 1 mm, and the thickness of the metal sheet material of the terminal 4 is 0. 4 mm, the thickness of the bottom plate 201 is 1.7 mm, and the level difference from the surface of the bottom plate 201 is 0.4.
mm. In the above embodiment, the pot type core 1
In the center portion of the top wall 101 of the rivet-type core 20, a through hole 102 is formed. It is one in which a road gap is formed. Here, another embodiment will be described with reference to FIG. 6. In this embodiment, the pot type core 10 does not have the through-hole 102 in the top wall 101, and only the lower peripheral edge is opened. An upper end surface of a magnetic core portion 204 erected at the center of the rivet-type core 20 is arranged on the lower surface of the top wall 101 of the pot-type core 10 so as to be closely opposed to each other to form a magnetic path gap. In this embodiment, the rectangular electric wire coil 3 is sealed in the space formed by the pot-shaped core 10 and the rivet-shaped core 20, and almost no magnetic flux leakage occurs.

As described above, by forming the core of the surface-mounted choke coil from the pot-rivet-type core in which the pot-type core and the rivet-type core are combined, the DC current superposition characteristics of the surface-mount choke coil can be improved. This is shown by the experimental results in FIG. FIG. 5A is a diagram showing a direct current-inductance characteristic curve of an experimental example of a surface mount choke coil using a core composed of a ring core and a drum core.
FIG. 5B is a diagram showing a DC current-inductance characteristic curve of an experimental example of a surface-mounted choke coil using a pot rivet core obtained by combining a pot core and a rivet core. Each of the choke coils has a dimension of 12.5 mm in height and width and 5.5 mm in height, and has a rated inductance of 10 μH. Measurement at room temperature 2
Performed at 5 ° C.

In the conventional example of FIG. 5A, the superimposed DC current is 4.
Although the characteristics suddenly decrease when the voltage slightly exceeds 0 A, the embodiment of FIG.
It is shown that it can be put to practical use as a product rated at 10 μH. Comparing the experimental example of the conventional example with the experimental example of the embodiment, the DC current superposition characteristic is improved by about 3.0 A. When the number of assembling work processes of the surface mount choke coil is reduced, the present invention is reduced from the conventional six processes to five processes, and it seems that the number is small. It can be easily understood how the individual work contents of the present invention are simplified and shorten the assembly work time.

In addition, as the electric wire constituting the coil 3, in particular, a flat rectangular electric wire having a rectangular cross section formed by cutting an extremely thin electric copper plate and coated with an insulating material is used. The internal resistance of the mounted choke coil can be reduced. That is, while a rectangular wire generally commercially available has a cross-sectional shape of an ellipse, a rectangular wire formed by the above manufacturing steps has a rectangular cross-sectional shape, and the rectangular cross-sectional shape is a rectangular rectangular wire. The ratio of the cross-sectional area of the rectangular wire itself to the cross-sectional area of the coil when the coil is formed can be almost 100%. This is advantageous for reducing the internal resistance of the surface mount choke coil and increasing the rated current of the surface mount choke coil. Compared with the case of purchasing a commercially available flat wire and thus forming the flat wire coil, the flat wire coil according to the present invention can reduce the manufacturing cost of the flat wire coil to about 1/3. Can be This contributes to reducing the manufacturing cost of the entire surface mount choke coil.

Further, the through hole 102 is not formed in the top wall 101 of the pot-shaped core 10 and only the lower peripheral edge is opened, and the flat wire coil 3 is connected to the pot-shaped core 10 and the rivet-shaped core 2.
By adopting a configuration in which sealing is performed in a space formed by zero, almost no leakage magnetic flux is generated.

[0024]

As described above, the direct current superposition characteristics of the surface mount choke coil are improved by forming the core of the surface mount choke coil by the pot rivet type core combining the pot type core and the rivet type core. can do. By adopting a configuration in which the coil is sealed in a space formed by the pot-type core and the rivet-type core, a surface-mounted choke coil with extremely low leakage magnetic flux can be obtained.

Further, by employing the above-mentioned pot rivet type core, the contents of the assembling work can be simplified, and the assembling work time can be shortened. Further, by adopting a rectangular wire coil in particular as an electric wire constituting the coil, the internal resistance of the surface-mounted choke coil can be reduced and the manufacturing cost of the entire surface-mounted choke coil can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an embodiment.

FIG. 2 shows an embodiment of the assembled choke coil.

FIG. 3 is a perspective view of a conventional example.

FIG. 4 is an exploded perspective view of the conventional example of FIG. 3;

FIG. 5 is a diagram illustrating DC current superposition characteristics.

FIG. 6 is a diagram for explaining another embodiment.

[Explanation of symbols]

 Reference Signs List 10 pot type core 101 top wall 102 through hole 103 side wall 104 cutout portion 20 rivet type core 201 bottom plate 202 fitting thin portion 203 terminal mounting surface 204 magnetic core portion 3 coil 31 coil terminal portion 4 terminal 44 mounting portion 45 coil connection Part 46 locking projection

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 37/00 H01F 15/10 F

Claims (6)

[Claims] 1. A rivet-type core having a pot-shaped core having a top wall and a side wall integrally formed with the top wall, and having a bottom plate and a magnetic core portion standing upright at the center of the bottom plate. Wherein a pot-shaped core and a rivet-shaped core are joined and fixed by forming a gap in a magnetic path by bringing the upper end face of the magnetic core portion close to and facing the lower surface of the top wall of the pot-shaped core, Riveted core surface mount choke coil. 2. A pot type core comprising a top wall having a through hole formed in the center and a side wall integrally formed with the top wall, and a bottom plate and a bottom plate being integrally erected at the center thereof. A pot-rivet-type core surface-mounted choke coil having a rivet-type core comprising a magnetic core portion, wherein the pot-type core and the rivet-type core are joined and fixed in a state where the magnetic core portion is inserted into a through hole. 3. The pot rivet-type core surface mount choke coil according to claim 1, wherein the terminal is fixed to the bottom plate, and the coil terminal portion of the coil is connected to the terminal. Features pot rivet type core surface mount choke coil. 4. The pot rivet-type core surface-mounted choke coil according to claim 3, wherein the terminal comprises a U-shaped cross section, a coil connection section integrally extended from the mounting section, and a bottom plate. A terminal mounting surface is formed on the surface, which is stepped down by an amount corresponding to the thickness of the terminal, and the terminal is mounted and fixed on the terminal mounting surface. coil. 5. The pot rivet type core surface mount choke coil according to claim 1, wherein the coil is formed by winding a round or square electric wire in cross section. A pot rivet type core surface mount choke coil characterized by the following. 6. The pot rivet type core surface mount choke coil according to any one of claims 1 to 4, wherein the coil is formed by cutting a flat copper wire formed by cutting an electrolytic copper plate into a spiral shape. A pot rivet type core surface mount choke coil formed by winding a rectangular electric wire formed by deforming and applying an insulating material coating on the surface.