JPS602653Y2 - electromagnetic interference filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic interference filter having an LCπ type circuit configuration.

Conventionally, as this type of electromagnetic interference filter, for example, the first
As shown in the figure, a single through shaft 4 is connected to the axial center of a ferrite bead 1 as an inductor and two plate-shaped capacitors 2 and 3 having the same diameter arranged on both sides of the ferrite bead 1, respectively. The positioning protrusion 5 penetrates the capacitor 3 until it comes into contact with the capacitor 3, and the electrode 2a of the capacitor 2 and the electrode 3a of the capacitor 3 are connected to the penetrating shaft 4 by ring soldering or the like.
On the other hand, the other electrode 2b of the capacitor 2 and the other electrode 3b of the capacitor 3 are soldered to the inner wall surface of the metal cylindrical case 6 by ring soldering or the like, and then the other electrode 2b of the capacitor 2 and the other electrode 3b of the capacitor 3 are soldered to the inner wall surface of the metal cylindrical case 6. The openings on both sides of the capacitor 6 are sealed with insulating resins 8 and 8, respectively, and as shown in FIG.
A circuit configuration of LCπ type consisting of and 3 is known.

7 is a washer fitted inside the cylindrical case 6.

However, when the electromagnetic interference filter is configured as described above, the opposing area between the electrode 2b of the capacitor 2 and the inner wall surface of the cylindrical case 6 and the opposing area between the electrode 3b of the capacitor 3 and the inner wall surface of the cylindrical case 6 In addition, there is an uneven gap between the electrodes 2b, 3b and the inner wall surface of the cylindrical case 6 due to variations in the diameters of the capacitors 2, 3. The soldering to the case 6 tends to be incomplete, and even if soldering is possible, the electromagnetic interference filter must be connected to the ground plate (not shown).

), etc., the heat generated during soldering between the cylindrical case 6 and the ground plate is transferred to the electrodes 2b of the capacitors 2 and 3.
, 3b, the cylindrical case 6 and the electrodes 2 of the capacitors 2 and 3
There is a drawback that the soldering between the aw 3a and the through shaft 4 is transmitted to some parts, and if the solder is remelted, the connection is easily broken.

Also, the electrode 2a of the capacitor 2 is removed by the remelted solder.
There was also a problem that the electrodes 3a and 2b of the capacitor 3 or the electrodes 3a and 3b of the capacitor 3 were short-circuited.

Further, since the washer 7 is fitted inside the cylindrical case 6 and the resin 8 is potted, there is a problem that the assembly is troublesome and the cost is high.

The present invention was made to solve the above-mentioned problems in conventional electromagnetic interference filters, and a filter unit is formed by arranging a small-diameter capacitor and a large-diameter capacitor on both sides of the inductor of a through shaft provided with an inductor. , the filter unit is fitted into a cylindrical case in which a first stage part and a second stage part are provided that connect the different diameter parts to each other;
Easy assembly by soldering one electrode of the small-diameter capacitor and large-diameter capacitor to the first and second stage sections, respectively, and soldering the other electrode to the through shaft. At the same time, the first stage part and the second stage part securely lock both capacitors and completely conductive connection by soldering between each electrode of the capacitor and the cylindrical case. The purpose is to provide a low-cost electromagnetic interference filter.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 3, 11 is a ferrite bead as an inductor, 12 is a disk-shaped small-diameter capacitor having a diameter d, and 13 is a diameter d1 larger than the small-diameter capacitor 12.
14 is a through shaft, and 15 is a metal cylindrical case.

The ferrite bead 11, the small diameter capacitor 12, and the large diameter capacitor 13 have through holes 16, 17, and 18 in their axial centers, respectively, and the small diameter capacitor 12 and the large diameter capacitor 13 are arranged coaxially on both sides of the ferrite bead 11. The through hole 16. ; through shaft 14 in 17 and 18;
The capacitor 12 is inserted until the positioning protrusion 19 provided on the side part of the through shaft 14 is stopped against the capacitor 13.
The electrode 12a formed in the through hole 17 and the capacitor 1
The electrodes 13a formed in the through holes 18 of No. 3 are connected to the two through holes 1, respectively.
4 with solders 20, 20 to form a filter unit consisting of ferrite beads 11, capacitors 12, 13, and a through shaft 14.

On the other hand, the cylindrical case 15 has a small diameter portion 21 having an inner diameter d□ smaller than the diameter d8 of the small diameter capacitor 412, and an inner diameter larger than the diameter d of the small diameter capacitor 12 and smaller than the diameter dl of the large diameter capacitor 13. d2 and a large diameter part 23 having an inner diameter larger than the diameter d1 of the large diameter capacitor 13, the small diameter part 21 and the middle diameter part 22 are connected by a tapered surface 24 to form a first While the stepped portion 25 is formed into a tapered surface 2, the medium diameter portion 22 and the large diameter portion 23 are formed into a tapered surface 2.
16 to form a second stage portion 27.

The above-described filter unit is fitted into the cylindrical case 15, and an electrode 12b formed on the outer peripheral surface of the small-diameter capacitor 12 is inserted into the cylindrical case 15.
is brought into contact with the tapered surface 24 of the first step portion 25 and soldered with the solder 20, while the electrode 13b formed on the outer peripheral surface of the large diameter capacitor 13 is brought into contact with the tapered surface 26 of the second step portion 27.
After soldering with solder 20 in contact with
8.28 are filled respectively.

1 If the electromagnetic interference filter has the above configuration, the second
An electromagnetic interference filter having an LCπ type circuit configuration similar to that shown in the figure can be obtained.

When assembling the electromagnetic interference filter, for example, as shown in FIG. 4, the large diameter capacitor 13, the ferrite bead 11, and the small diameter capacitor 12 are passed through the penetrating shaft 14 in this order, and then the whole is immersed in molten solder. Electrode 12a of small diameter capacitor 12 and electrode 13 of large diameter capacitor 13
a are respectively soldered to the through shaft 14 to form an integrated filter unit, and the electrode 12b of the small diameter capacitor 12 and the electrode 1 of the large diameter capacitor 13 are
The solder 20 also adheres to 3b.

Therefore, by inserting the filter unit into the cylindrical case 15 from the small diameter capacitor 12 side through its large diameter part 23, and heating the whole with the small diameter part 21 of the cylindrical case 15 facing downward, the electrodes 12b and 13b are heated. The attached solder will remelt,
The small diameter capacitor 12 and the large diameter capacitor 13 are soldered 2.
The electrode 12 moves slightly downward by its own weight by the thickness of
b and 13b are respectively soldered to the tapered surfaces 24 and 26 in contact with each other, and the fixing of the filter unit into the cylindrical case 15 is also completed, making assembly very simple.

In this case, the solder fixing the electrodes 12a, 13a of the capacitor 12° 13 and the through shaft 14 will also be remelted, but since the capacitor 12° 13 will hardly move, there is no risk of the connection being broken. .

In case 2, even if the diameter d of the small diameter capacitor 12 and the diameter d1 of the large diameter capacitor 13 have variations, d
If □< d - < d2, da < di < ton, the electrodes 12b and 13b will definitely come into contact with the tapered surfaces 24 and 26, respectively, so the soldering between these electrodes 12b and 13b and the cylindrical case 15 will be ensured. It can be carried out.

Note that the small diameter portion 21 and the medium diameter portion 22 and the medium diameter portion 22 and the large diameter portion 23 of the cylindrical case 15 are formed into tapered surfaces 24 and 26, respectively.
Instead of connecting with the cylindrical case 1 as shown in FIG.
They may also be connected at surfaces 24' and 26' perpendicular to the axial direction of 5, respectively.

Furthermore, various structures can be used as the small diameter capacitor 12 and the large diameter capacitor 13. For example, as shown in FIG. While a feedthrough capacitor 12' having a protrusion 31 is used, a multilayer capacitor 13' may be used as the large diameter capacitor 13.

Naturally, this combination of capacitors is not limited to those of these embodiments.

In the embodiment shown in FIG. 5, the inner diameter of the small diameter portion 21 of the cylindrical case 15 is increased at the opening, and the tip 31' of the protrusion 31 of the feedthrough capacitor 32 is made to protrude into the larger inner diameter of the small diameter portion 21. This is preferable in order to prevent a short circuit between the electrode 12'b and the other electrode 12'a due to remelting of the solder attached to the electrode 12'b provided on the outer periphery of the protrusion 31.

Furthermore, in the above embodiment, the capacitor, ferrite bead, and through shaft were shown as being assembled into a unit before being loaded into the cylindrical case, but they were individually loaded into the cylindrical case and finally integrated. Needless to say, this is a good thing.

Furthermore, in each of the above embodiments, ferrite beads are used as the inductor, but the point is that the inductor should just be attached to the through shaft, and for example, a coil 30 as shown in FIG. core 31 wound with
The inductor may be arranged in the center of the through shaft 14, or may be constructed of only a coil without using a core at all.

In any of these cases, it goes without saying that both ends of the coil must be electrically connected to the through shaft.

As is clear from the detailed explanation above, the present invention involves fitting a capacitor, an inductor, and a through shaft into a metal cylindrical case with two steps inside, and Because one electrode of the capacitor is soldered while touching the upper part of the capacitor, the holding, positioning, and soldering of the capacitor and inductor are secure, and the electromagnetic interference filter is extremely easy to assemble. In addition, it is possible to prevent troubles such as the connection being broken or a short circuit occurring due to remelting of the solder, which is very effective.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional electromagnetic interference filter, Fig. 2 is an equivalent circuit diagram of Fig. 1, Fig. 3 is a sectional view of an electromagnetic interference filter according to the present invention, and Fig. 4 is an electromagnetic interference filter according to the present invention. 5 is a cross-sectional view of a modification of FIG. 2;
The figure is a plan view of an inductance element using a coil. 11... Ferrite beads, 12...
Small diameter capacitor, 13...Large diameter capacitor, 1
4... Penetration shaft, 15... Cylindrical case,
21...Small diameter part, 22...Medium diameter part, 2
3...Large diameter part, 24...Tapered surface, 2
5...First step part, 26...Tapered surface,
27...Second stage section.

Claims (1)

[Scope of utility model registration request] A small-diameter capacitor and a large-diameter capacitor are arranged on both sides of the inductor of a through shaft provided with an inductor, and these are connected to a first stage part that connects the small-diameter part and the medium-diameter part to each other, and a first stage part that connects the small-diameter part and the medium-diameter part to each other, and The electrodes of each of the small diameter capacitor and the large diameter capacitor are mounted in the first stage part and the second stage part, respectively, inside a metal cylindrical case that includes a second stage part that connects the diameter parts with each other. Solder one electrode of the small diameter capacitor and large diameter capacitor to the first and second stage parts, and solder the other electrode to the through shaft. An electromagnetic interference filter characterized by: