JPH02235419A - Noise filter - Google Patents

Abstract

PURPOSE:To obtain a noise filter small in size and excellent in noise attenuation characteristic by arranging and containing 2 choke coils or over to a box shaped metallic case side by side, placing a magnetic metallic plate between the choke coils so as to separate them and connecting the plate with the box type metallic case. CONSTITUTION:Common mode choke coils 1, 2, noise attenuation capacitors 4, 5 connecting between line and earth and noise attenuation capacitors 8, 9 between lines are arranged to a box shaped metallic case 10 made of a magnetic metallic such as an iron group material or a nonmagnetic metallic plate in parallel with both end faces from an input terminal 11 to an output terminal 12 sequentially. Then a magnetic metallic plate 13 made of an iron group material or the like and having a small hole for wiring is inserted in parallel with the input and output end faces and connected by soldering or welding. Moreover, the input terminal 11, the output terminal 12 and each component terminal and ground are wired and connected with lead wires, a resin material is packed in the case 10 to fix each component.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a noise filter that is inserted into a power supply line to prevent noise from entering and leaking.

BACKGROUND OF THE INVENTION The circuit diagram of a conventional noise filter using two or more choke coils is shown in Figure 7, and the schematic plan view of a noise filter using two choke coils is shown in Figure 8. A schematic side view is shown in Fig. 9.

1, 2.3 are common mode choke coils in which a pair of windings are applied to a magnetic core made of a ferrite core or an amorphous metal so that the magnetic flux due to reciprocating flow is canceled out; .7 is a common mode noise reduction capacitor connected between the line and ground. 8,9.1
0 is a normal mode noise reduction capacitor connected between lines. The conventional noise filter is
figure. As shown in Fig. 9, these parts are placed in a box-shaped metal case 10 in parallel from the input terminal 11 side to the output terminal 12 side, and the lead wires and ground wires are connected. A noise filter was constructed by fixing the components in a box-shaped metal case 19 with a filler.

Problems to be Solved by the Invention In the conventional configuration described above, magnetic coupling occurs between the two adjacent common mode choke coils 1 and 2, and the attenuation effect of the noise filter occurs in both the common mode and the normal mode. is greatly reduced compared to the case without magnetic coupling. Also, to eliminate the influence of magnetic coupling,
It is necessary to place the two common mode choke coils 1 and 2 far apart, which has the drawback of increasing the size and cost of the noise filter.

As a solution to the above problems, the present invention provides a noise filter that is small and has excellent noise attenuation characteristics.

Means for Solving the Problems In order to solve the above problems, the present invention arranges and houses two or more choke coils in parallel in a box-shaped metal case, and divides the choke coils with magnetic metal plates. A noise filter is constructed by connecting this to a box-shaped metal case.

Function As mentioned above, since the two choke coils are partitioned by a magnetic metal plate, the magnetic flux leaking from each choke coil passes through the magnetic metal plate without interlinking with the other coil. Magnetic flux flows to the case or outside.

Therefore, the magnetic coupling between the notches and the notch coils becomes extremely small, and the deterioration of the noise attenuation characteristics of the noise filter is also reduced, making it possible to downsize the noise filter.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 are a schematic plan view and a schematic side view of a noise filter in an embodiment of the present invention. Figure 3,
FIG. 4 is a schematic plan view and a schematic side view of a noise filter in another embodiment. The case where two choke coils are used (indicated by dotted lines) in the noise filter circuit diagram of FIG. 7 will be described. A box-shaped metal case 1o made of a magnetic metal such as a ferrous material or a non-magnetic metal plate includes common mode quadrature coils 1 and 2, line-to-ground noise attenuation capacitors 4 and 6, and line-to-line noise attenuation capacitor 8. , 9 are sequentially arranged from the input terminal 11 side to the output terminal 12 side parallel to both end faces. Next, a magnetic metal plate 13 made of iron-based material or the like with a small hole for wiring is inserted into the approximately center position of the two common mode Chirok coils 1 and 2 parallel to the input/output end faces, and soldered. ,
Connect by welding, etc. The input terminal 11, the output terminal 12, each component terminal, and the ground are wired with lead wires, connected by soldering, etc., and the box-shaped metal case 10 is filled with resin material and fixed to each component to form a noise filter. This is what I did.

FIGS. 5 and 6 show a comparison of the common mode (line-to-ground) and normal mode (line-to-line) attenuation characteristics when the magnetic metal plate 13 is used as a partition and when it is not partitioned. When partitioned with the magnetic metal plate 13, the attenuation effect can be particularly improved in the high frequency range.

Furthermore, if you want to improve the attenuation effect in the high frequency range, as shown in FIGS. 3 and 4, a feedthrough capacitor 14 is attached to the magnetic metal plate 13 as a line-to-ground noise attenuation capacitor, and the feedthrough capacitor 14 and the feedthrough terminal By connecting the line lead wire, the outer peripheral electrode, and the magnetic metal plate 1a, the inductance component of the ground lead wire can be minimized, and the high frequency attenuation characteristics can be improved.

Effects of the Invention According to the present invention as described above, when configuring a noise filter by arranging two or more chip coils in parallel in a box-shaped metal case, a magnetic metal plate is inserted between each chip coil. This prevents magnetic coupling between the respective choke coils and makes it possible to obtain a good noise attenuation effect.

This not only makes it possible to downsize the noise filter, but also has the effect of shielding radiation noise between input and output, which is of great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a noise filter according to an embodiment of the present invention, FIG. 2 is a schematic side view of the embodiment, FIG. 3 is a schematic plan view of a noise filter according to another embodiment, and FIG. 4 is a schematic plan view of a noise filter according to another embodiment. Schematic side view of the example, Figure 6. Figure 6 shows
Attenuation characteristic diagram of the present invention and conventional noise filter, seventh
8 is a schematic plan view of a conventional noise filter, and FIG. 9 is a schematic side view of the conventional noise filter. 1, 2.3...Common mode tick coil, 4, 5, 8.9...●Noise attenuation capacitor, 10...Box-shaped metal case, 13.・・・・・・
Magnetic metal plate, 14... Feedthrough capacitor. Name of agent: Patent attorney Shigetaka Awano and one other person 1.
2 ---- Common - Dona Cork Fill Diagram Figure L2-11 Con Mode + Yog Coil

Claims (2)

[Claims] (1) A noise filter in which two or more choke coils are arranged and housed in parallel in a box-shaped metal case, a magnetic metal plate is used as a partition between the choke coils, and the choke coils are connected to the box-shaped metal case. (2) The noise filter according to claim 1, wherein a feedthrough capacitor is attached to a magnetic metal plate and connected to a lead wire of a choke coil.