JPH025626Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a noise filter used as a power line filter inserted into a power line to remove noise.

In this type of noise filter, a structure has been proposed in which two toroidal common mode choke coils are connected in series in order to improve the noise removal effect. FIG. 1 shows an example of the circuit configuration of a noise filter using two toroidal common mode choke coils. In this figure, toroidal common mode chain coil 1,
2 is a pair of windings 1A, 1B and 2A, 2B respectively.
The windings 1A and 2A are connected in series, and similarly the windings 1B and 2B are connected in series. Here, a series circuit of windings 1A and 2A is connected between input and output terminals 3A and 3C, and windings 1B and 2B
The series circuit is connected between input/output terminals 3B and 3D. Normal mode capacitors 4 and 5 are connected between the input and output terminals 3A and 3B and between the input and output terminals 3C and 3D, respectively. In addition, a normal mode capacitor 6 is connected between the connection point between the windings 1A and 2A and the connection point between the windings 1B and 2B, and common mode capacitors 7A and 7B are connected between each connection point and the ground. Connected.

However, in a structure using two toroidal common mode choke coils as shown in FIG. 1, electromagnetic coupling between the two coils becomes a problem. Assuming that the toroidal common mode choke coils 1 and 2 are installed parallel to the bottom of the box-shaped metal case and on almost the same plane, the electromagnetic coupling between the windings 1A and 2A and between the windings 1A and 2B will be This results in an inconvenience that the noise removal effect becomes considerably large and the noise removal effect decreases accordingly.

For this reason, a structure has been considered in which the toroidal common mode choke coils 1 and 2 are arranged vertically to the bottom surface of the box-shaped metal case 10 as shown in FIG. In FIG. 2, 11 and 12 are insulating sheets, and 13 is a metal case lid. Note that the inside of the box-shaped metal case 10 is usually molded with resin.

As described above, according to the configuration shown in FIG. 2, by erecting each toroidal common mode choke coil perpendicularly to the bottom surface of the case, electromagnetic coupling between the coils can be reduced. but,
If the shape of the metal case lid 13 is not devised, the height X of the box-shaped metal case 10 will become large, which will be an obstacle in reducing the external dimensions.

In view of the above points, the present invention has been developed to improve the shape of the metal case lid by forming a curved part in an arc shape corresponding to the outer periphery of the toroidal coil. The present invention aims to provide a noise filter that has a reduced external size and improved heat dissipation effect from the metal case lid side.

Embodiments of the noise filter according to the present invention will be described below with reference to the drawings.

In Figures 3 and 4, the box-shaped metal case 2
A notch 21 is formed on both end surfaces of the terminal 0, and terminal plates 22A and 22B each having a groove that fits into the notch 21 are fitted. and,
Input/output terminals 3A to 3D on terminal boards 22A and 22B
will be provided. Here, input/output terminals 3A to 3D
The circuit configuration of the filter element connected between them is the same as that shown in FIG. The device is stored in the same state and predetermined wiring is performed. On the other hand, the metal case lid 30 includes a bent part 31 that contacts the inner surface of the box-shaped metal case 20, and a curved part 32 formed in an arc shape corresponding to the outer periphery of each toroidal common mode chiyoke coil 1, 2. It has mounting portions 33 integrally formed on both sides, and mounting holes 34 are formed in each of the mounting portions 33. This metal case lid 30 is welded to the opening edge of the box-shaped metal case 20 at its bent portion 31 by spot welding or the like, with an insulating sheet 35 provided inside thereof. Note that the inside of the box-shaped metal case 20 is usually molded with resin in order to position and fix each coil and capacitor and to dissipate heat.

According to the configuration of the above embodiment, the toroidal common mode choke coils 1 and 2 are connected to the box-shaped metal case 2.
Even when the box-shaped metal case 20 is installed perpendicular to the bottom surface of the box-shaped metal case 20, the height dimension of the box-shaped metal case 20 does not need to be that large because the curved portion 32 is formed on the metal case lid 30 side. It is possible to reduce the external dimensions without any problems. In addition, metal case lid 3
Since the curved portion 32 of 0 is curved along the outer periphery of the toroidal common mode choke coils 1 and 2, heat can be effectively radiated from the metal case lid 30. Furthermore, the metal case 30 can be manufactured extremely easily by press working or the like, and is advantageous in terms of cost.

Although the above embodiment shows the case where two toroidal common mode choke coils are used, it is clear that the present invention is also effective in the case where one or three or more toroidal common mode choke coils are used.

As explained above, according to the present invention, when a toroidal coil is installed in a box-shaped metal case vertically to the bottom surface of the case, the metal case lid is formed in an arc shape corresponding to the outer circumference of the toroidal coil. By providing the curved portion, it is possible to obtain a noise filter whose external dimensions are reduced and whose heat dissipation effect is improved.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of the circuit configuration of a noise filter using two toroidal common mode choke coils, and Figure 2 is an example of a structure in which toroidal coils are arranged vertically in a box-shaped metal case. 3 is an exploded perspective view showing an embodiment of the noise filter according to the present invention, and FIG. 4 is a sectional view thereof. 1, 2...Toroidal common mode choke coil, 3A to 3D...Input/output terminal, 4, 5,
6,7A,7B...Capacitor, 10,20...
Box-shaped metal case, 13,30...metal case lid,
21... Notch portion, 22A, 22B... Terminal board,
31...Bending part, 32...Curving part, 33...Mounting part, 34...Mounting hole.

Claims (1)

[Scope of utility model registration request] A toroidal coil is disposed in a box-shaped metal case vertically to the bottom surface of the case, and a curved portion is formed in an arc shape corresponding to a bent portion that contacts an inner surface of the box-shaped metal case and an outer periphery of the toroidal coil. A noise filter characterized in that a metal case lid having a portion is welded to an opening edge of the box-shaped metal case.