JP2001110654A - Line filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line filter capable of simultaneously removing both common mode and normal mode noises. SOLUTION: This line filter is provided with a first noise-removing means for removing common mode noise 29 and a second noise-removing means for removing normal mode noise 30, the second noise-removing means makes magnetic flux A and B generated from one winding wire 23 and another winding wire 24 flow to a center magnetic core 28 in the same direction and makes the magnetic flux flow to a closed magnetic domain magnetic core 27 in mutually opposite directions and inside the closed magnetic domain magnetic core 27, the normal mode noise 30 is removed by mutually non-canceling the magnetic flux A and B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line filter for removing common mode noise and normal mode noise used in various consumer appliances and the like.

[0002]

2. Description of the Related Art A conventional line filter will be described below with reference to the drawings.

FIG. 24 is a perspective view of a conventional line filter.
FIG. 25 is a front sectional view of the line filter, FIG. 26 is an electric circuit diagram showing propagation of common mode noise when the line filter is used, and FIG. 27 is a magnetic diagram showing a flow of magnetic flux caused by common mode noise of the line filter. FIG. 3 is an explanatory diagram of a circuit.

In FIG. 24 and FIG. 25, a conventional line filter includes a bobbin 2 having a through hole 1 and a bobbin 2 having a through hole 1.
And a closed winding magnetic core 5 inserted into the through hole 1 of the bobbin 2.

In FIGS. 26 and 27, a noise removing means for removing the common mode noise 6 is provided.
This noise removing means causes the magnetic fluxes A and B generated from the one winding 3 and the other winding 4 to flow in the closed magnetic circuit core 5 in the same direction as each other and so as to cancel each other out. It is a means to remove.

With the above configuration, as shown in FIG. 26, when the common mode noise 6 propagates to the electric circuit, the directions of the magnetic fluxes A and B generated in the line filter are as shown in FIG.

That is, in FIG. 27, one winding 3
The generated magnetic flux A and the magnetic flux B generated from the other winding 4 flow in the closed magnetic circuit core 5 so as to be in the same direction, add to each other, and cancel each other.

[0008]

Generally, high frequency noise current generated in an electric circuit through a commercial power supply includes:
There are an in-phase current and a differential current. The former is called common mode noise, and the latter is called normal mode noise.

In the above-mentioned conventional configuration, the common mode noise 6 can be removed, but at the same time, the normal mode noise cannot be removed.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide a line filter capable of simultaneously removing both common mode noise and normal mode noise.

[0011]

According to the present invention, there is provided a bobbin having a through-hole, a winding wound around the bobbin, and a magnetic leg inserted into the through-hole of the bobbin. And a closed magnetic circuit core in which the other magnetic leg facing the one magnetic leg is disposed outside the through hole, a center magnetic core disposed in the center of the bobbin, and a second mode for removing common mode noise. (1) noise removing means, and second noise removing means for removing normal mode noise, wherein the center magnetic core is a U-shaped magnetic core having a concave portion having an open end, and the center magnetic core has a concave portion. One magnetic leg of the closed magnetic circuit core is inserted into the center of the bobbin to be disposed in the recess of the center magnetic core, and the tip of the center magnetic core and the other magnetic leg of the closed magnetic circuit core are inserted. Are arranged to face each other, and A first air gap is provided between the tip of the core core and the other magnetic leg of the closed magnetic path core; The second noise eliminator is configured to cause the magnetic flux generated from the one winding and the other winding to flow in the same direction in the center core, The magnetic flux is caused to flow in the path magnetic cores in opposite directions, and in the closed magnetic path magnetic core, the magnetic fluxes do not cancel each other out to remove normal mode noise.

[0012] According to the above configuration, the common mode noise can be removed by the first noise removing means.
By the noise removing means, a magnetic flux generated from one winding and the other winding is caused to flow in the center magnetic core in the same direction, and is caused to flow in the closed magnetic core in opposite directions. In the closed magnetic circuit core, the normal mode noise can be removed so that the magnetic fluxes do not cancel each other, and both the common mode noise and the normal mode noise can be removed.

In particular, the center magnetic core is a U-shaped magnetic core having a concave portion with an open end, and the concave portion of the center magnetic core is inserted into the center of the bobbin so that the closed magnetic path magnetic core is inserted into the concave portion of the center magnetic core. One magnetic leg of the core is arranged, and the tip of the center magnetic core and the other magnetic leg of the closed magnetic path core are arranged to face each other. The first air gap is provided between the magnetic core and the leg, and the bottom surface and the inner surface of the concave portion of the center magnetic core are not in contact with one magnetic leg of the closed magnetic core. In addition, the occurrence of magnetic saturation of the closed magnetic circuit core can be suppressed, and common mode noise can be accurately removed.
Normal mode noise can also be efficiently removed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION
A bobbin having a through-hole, one winding and the other winding wound around the bobbin, and one magnetic leg inserted into the through-hole of the bobbin and the other magnetic facing the one magnetic leg. A closed magnetic path magnetic core having legs disposed outside the through hole, a center magnetic core disposed at the center of the bobbin so as to be located between the one winding and the other winding, and a common core. A first noise removing unit that removes mode noise, and a second noise removing unit that removes normal mode noise, wherein the center magnetic core is a U-shaped magnetic core having a concave portion having an open end. Inserting the recess of the center core into the center of the bobbin, and disposing one magnetic leg of the closed magnetic path core in the recess of the center core,
The tip of the center magnetic core and the other magnetic leg of the closed magnetic path core are arranged so as to face each other, and a third magnetic core is disposed between the tip of the center magnetic core and the other magnetic leg of the closed magnetic path core. And a bottom portion and an inner side surface of the concave portion of the center magnetic core are brought into non-contact with one magnetic leg portion of the closed magnetic core, and the second noise removing means includes the one winding and the The magnetic flux generated from the other winding flows in the center magnetic core in the same direction as each other, and flows in the closed magnetic path core in opposite directions to each other.
In this configuration, the magnetic fluxes cancel each other to remove normal mode noise.

With the above configuration, the first noise removing means can remove the common mode noise, and the second noise removing means transfers the magnetic flux generated from one of the windings and the other winding to the center magnetic core. Flow in the same direction as each other, and flow in opposite directions to the closed magnetic circuit core, so that the magnetic flux does not cancel each other out in the closed magnetic circuit core, and normal mode noise can be removed. ,
Both common mode noise and normal mode noise can be removed.

In particular, the center magnetic core is a U-shaped magnetic core having a concave portion with an open end, and the concave portion of the center magnetic core is inserted into the center of the bobbin so that a closed magnetic circuit magnetic core is formed in the concave portion of the center magnetic core. One magnetic leg of the core is arranged, and the tip of the center magnetic core and the other magnetic leg of the closed magnetic path core are arranged to face each other. The first air gap is provided between the magnetic core and the leg, and the bottom surface and the inner surface of the concave portion of the center magnetic core are not in contact with one magnetic leg of the closed magnetic core. In addition, the occurrence of magnetic saturation of the closed magnetic circuit core can be suppressed, and common mode noise can be accurately removed.
Normal mode noise can also be efficiently removed.

The second aspect of the present invention is the first aspect.
In the invention described in (1), a second gap is provided between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core.

With the above configuration, normal mode noise can be further removed.

The third aspect of the present invention provides the first aspect.
In the invention described in the above, the cross-sectional shape of one magnetic leg of the closed magnetic path core is polygonal, and the one magnetic leg surface of the closed magnetic path core and the inner side surface of the recess of the center magnetic core are opposed to each other.
The configuration is such that the width dimension of the concave portion of the center magnetic core is smaller than the maximum sectional width dimension of the one magnetic leg.

With the above configuration, normal mode noise can be further removed.

[0021] The invention described in claim 4 of the present invention is claim 1.
In the invention described in the above, the half shape of the concave portion of the center magnetic core is similar to the cross-sectional shape of one magnetic leg of the closed magnetic path magnetic core.

With the above structure, the concave portion of the center magnetic core and the one magnetic leg of the closed magnetic circuit core are opposed to each other with a larger area, so that there is no magnetic saturation or concentration of magnetic flux, and the normal mode noise is efficiently removed. can do.

The invention according to claim 5 of the present invention is the invention according to claim 1.
In the invention described in the above, a through window is provided at the center of the bobbin facing one magnetic leg of the closed magnetic circuit core, and the inner side surface of the recess of the center magnetic core and the closed magnetic circuit core are provided through the through window. This is a configuration in which one magnetic leg portion is opposed.

With the above configuration, normal mode noise can be further removed.

The present invention according to claim 6 of the present invention is directed to claim 5
In the invention described in the above, the bobbin end surfaces of both ends of the through window are projected outward from the end surface of the through window, and the bobbin end surface is brought into contact with the inner side surface of the concave portion of the center magnetic core to form a closed magnetic circuit core. One magnetic leg portion and the inner side surface of the concave portion of the center magnetic core are not in contact with each other.

With the above configuration, the center magnetic core can be accurately positioned.

The seventh aspect of the present invention is the first aspect of the present invention.
In the invention described above, the minimum size of the first gap portion is configured to be equal to or larger than the minimum size between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core.

According to the above configuration, when the power of removing normal mode noise is large, the power of removing normal mode noise can be easily reduced without impairing the power of removing common mode noise.

[0029] The invention according to claim 8 of the present invention is the invention according to claim 1.
In the invention described above, the minimum size of the first void portion is configured to be equal to or less than the minimum size between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core.

According to the above configuration, when the power of removing common mode noise is large, the power of removing common mode noise can be easily reduced without impairing the power of removing normal mode noise.

The ninth aspect of the present invention is the first aspect.
In the described invention, the tip of the center magnetic core is configured to face the side surface of the other magnetic leg portion of the closed magnetic circuit core.

According to the above configuration, when the power of removing the common mode noise is large, the power of removing the common mode noise can be easily reduced without impairing the power of removing the normal mode noise.

According to a tenth aspect of the present invention, in the first aspect of the present invention, a tapered portion is provided at a leading end of the center magnetic core, and the tapered portion has a tip with a closed magnetic path core other than a root. This is a configuration provided so as to be separated from the magnetic leg.

With the above structure, the distance between the tapered portion of the center magnetic core and the other magnetic leg of the closed magnetic circuit core can be finely adjusted, and the relationship between the common mode noise removing power and the normal mode noise removing power can be finely adjusted. it can.

According to an eleventh aspect of the present invention, there is provided a bobbin having a through hole, a winding wound around the bobbin, and a magnetic leg inserted into the through hole of the bobbin. A closed magnetic path magnetic core in which the other magnetic leg facing the leg is disposed outside the through-hole, a center magnetic core disposed in the center of the bobbin, and first noise removing means for removing common mode noise; A second noise removing means for removing normal mode noise, wherein the center magnetic core is a U-shaped magnetic core having a concave portion with an open end, and the concave portion of the center magnetic core is provided at a central portion of the bobbin. Inserting and placing one magnetic leg of the closed magnetic circuit core in the concave portion of the center magnetic core, so that the side surface of the center magnetic core faces the other magnetic leg of the closed magnetic circuit core. Arrange the side part of the center magnetic core A first gap portion is provided between the other magnetic leg of the closed magnetic core and the bottom surface and the inner side surface of the concave portion of the center magnetic core are brought into non-contact with one magnetic leg of the closed magnetic core, The second noise removing means causes the magnetic flux generated from the one winding and the other winding to flow in the center magnetic core so as to be in the same direction as each other, and to cause the closed magnetic circuit core to rotate in the opposite direction. In the closed magnetic circuit core, the magnetic fluxes do not cancel each other out to remove normal mode noise.

With the above configuration, the same effect as that of the first aspect can be obtained.

According to a twelfth aspect of the present invention, in the eleventh aspect, a second gap is provided between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic circuit core. It is a configuration provided.

With the above configuration, normal mode noise can be further removed.

According to a thirteenth aspect of the present invention, in the eleventh aspect of the present invention, the cross-sectional shape of one magnetic leg of the closed magnetic circuit core is polygonal, and the one magnetic leg of the closed magnetic circuit core is formed. The surface and the inner side surface of the concave portion of the center magnetic core are opposed to each other, and the width of the concave portion of the center magnetic core is smaller than the maximum cross-sectional width of the one magnetic leg portion. .

With the above configuration, normal mode noise can be further removed.

According to a fourteenth aspect of the present invention, in the eleventh aspect, the half shape of the concave portion of the center magnetic core is similar to the cross-sectional shape of one magnetic leg of the closed magnetic path magnetic core. It is.

According to the above configuration, since the concave portion of the center magnetic core and the one magnetic leg of the closed magnetic path magnetic core face each other with a larger area, there is no magnetic saturation or concentration of magnetic flux, and the normal mode noise is efficiently removed. can do.

According to a fifteenth aspect of the present invention, in the eleventh aspect, a through window is provided at a central portion of the bobbin facing one magnetic leg of the closed magnetic circuit core, and the through window is provided through the through window. In this configuration, the inner surface of the concave portion of the center magnetic core faces one magnetic leg of the closed magnetic circuit core.

With the above configuration, normal mode noise can be further removed.

According to a sixteenth aspect of the present invention, in the invention according to the fifteenth aspect, the bobbin end faces at both ends of the through window are projected outward from the end face of the through window.
The end surface of the bobbin is brought into contact with the inner surface of the concave portion of the center magnetic core, and the one magnetic leg of the closed magnetic circuit core is not in contact with the inner surface of the concave portion of the center magnetic core.

With the above configuration, the center core can be accurately positioned. .

According to a seventeenth aspect of the present invention, in the eleventh aspect, the minimum size of the first gap is:
In this configuration, the distance between the inner surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic circuit core is equal to or larger than the minimum dimension.

According to the above configuration, when the power of removing normal mode noise is large, the power of removing normal mode noise can be easily reduced without impairing the power of removing common mode noise.

According to an eighteenth aspect of the present invention, in the eleventh aspect, the minimum size of the first gap is:
In this configuration, the distance between the inner surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic circuit core is smaller than the minimum dimension.

According to the above configuration, when the power of removing common mode noise is large, the power of removing common mode noise can be easily reduced without impairing the power of removing normal mode noise.

According to a nineteenth aspect of the present invention, there is provided a bobbin having a through hole, a winding wound around the bobbin, and a magnetic leg inserted into the through hole of the bobbin. A closed magnetic path magnetic core in which the other magnetic leg facing the leg is disposed outside the through-hole, a center magnetic core disposed in the center of the bobbin, and first noise removing means for removing common mode noise; A second noise removing means for removing normal mode noise, wherein the center magnetic core is a U-shaped magnetic core having a concave portion with an open end, and the concave portion of the center magnetic core is provided at a central portion of the bobbin. In addition, one magnetic leg of the closed magnetic circuit core is disposed in the concave portion of the center magnetic core, and the back surface of the center magnetic core faces the other magnetic leg of the closed magnetic circuit core. Arrange the back part of the center core A first gap portion is provided between the other magnetic leg of the closed magnetic core and the bottom surface and the inner side surface of the concave portion of the center magnetic core are brought into non-contact with one magnetic leg of the closed magnetic core, The second noise removing means causes the magnetic flux generated from the one winding and the other winding to flow in the center magnetic core so as to be in the same direction as each other, and to cause the closed magnetic circuit core to rotate in the opposite direction. In the closed magnetic circuit core, the magnetic fluxes do not cancel each other out to remove normal mode noise.

With the above configuration, the same effect as that of the first aspect can be obtained.

According to a twentieth aspect of the present invention, in accordance with the nineteenth aspect, a second gap is provided between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core. It is a configuration provided.

With the above configuration, normal mode noise can be further removed.

According to a twenty-first aspect of the present invention, in the nineteenth aspect of the present invention, the cross-sectional shape of one magnetic leg of the closed magnetic circuit core is polygonal, and the one magnetic leg of the closed magnetic circuit core is formed. The surface and the inner side surface of the concave portion of the center magnetic core are opposed to each other, and the width of the concave portion of the center magnetic core is smaller than the maximum cross-sectional width of the one magnetic leg portion. .

With the above configuration, normal mode noise can be further removed.

According to a twenty-second aspect of the present invention, in the nineteenth aspect, the half shape of the concave portion of the center magnetic core is similar to the cross-sectional shape of one magnetic leg of the closed magnetic core. It is.

With the above configuration, the concave portion of the center magnetic core and the one magnetic leg of the closed magnetic circuit core are opposed to each other with a larger area, so that there is no magnetic saturation or concentration of magnetic flux, and the normal mode noise is efficiently removed. can do.

According to a twenty-third aspect of the present invention, in the nineteenth aspect, a through window is provided at a central portion of a bobbin facing one magnetic leg of a closed magnetic circuit core, and the through window is provided through the through window. In this configuration, the inner surface of the concave portion of the center magnetic core faces one magnetic leg of the closed magnetic circuit core.

According to the above configuration, normal mode noise can be further removed.

According to a twenty-fourth aspect of the present invention, in the invention according to the twenty-third aspect, the bobbin end faces at both ends of the through window are made to protrude outward from the end face of the through window.
The end surface of the bobbin is brought into contact with the inner surface of the concave portion of the center magnetic core, and the one magnetic leg of the closed magnetic circuit core is not in contact with the inner surface of the concave portion of the center magnetic core.

With the above configuration, the center magnetic core can be accurately positioned.

According to a twenty-fifth aspect of the present invention, in the nineteenth aspect, the minimum dimension of the first void portion is:
The minimum dimension between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic path magnetic core is set.

According to the above configuration, when the power of removing normal mode noise is large, the power of removing normal mode noise can be easily reduced without impairing the power of removing common mode noise.

According to a twenty-sixth aspect of the present invention, in the nineteenth aspect, the minimum size of the first void portion is:
This configuration is smaller than the minimum dimension between the bottom surface of the concave portion of the center core and one magnetic leg of the closed magnetic core.

According to the above configuration, when the power of removing the common mode noise is large, the power of removing the common mode noise can be easily reduced without impairing the power of removing the normal mode noise.

(Embodiment 1) Hereinafter, a line filter according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a line filter according to a first embodiment of the present invention, FIG. 2 is a side sectional view of the line filter, and FIG. 3 is a combination of a closed magnetic path core and a center core of the line filter. FIG. 4 is a magnetic circuit diagram showing the flow of magnetic flux caused by normal mode noise of the line filter, FIG. 5 is an electric circuit diagram showing propagation of normal mode noise when the line filter is used,
6 is a magnetic circuit diagram showing the flow of magnetic flux caused by the common mode noise of the line filter, FIG. 7 is an electric circuit diagram showing propagation of the common mode noise when the line filter is used, and FIG. FIG. 6 is a characteristic diagram showing a superimposed current of normal mode noise-inductance change rate.

1 to 3, a line filter according to a first embodiment of the present invention includes a bobbin 22 having a through hole 21 and one winding 2 wound around the bobbin 22.
3 and the other winding 24, and one magnetic leg 25 is inserted into the through hole 21 of the bobbin 22, and the other magnetic leg 26 facing the one magnetic leg 25 is disposed outside the through hole 21. Path core 27, one winding 23 and the other winding 24
, A center magnetic core 28 disposed at the center of the bobbin 22, first noise removing means for removing common mode noise 29, and second noise removing means for removing normal mode noise 30. Have.

4 and 5, the second noise removing means applies the magnetic fluxes A and B generated from the one winding 23 and the other winding 24 to the center magnetic core 28 in the same direction. The magnetic fluxes A and B flow in the closed magnetic circuit core 27 so that the directions of the magnetic fluxes A and B are opposite to each other.
Normal mode noise 3
0, and the first noise removing means is the same as the conventional one. However, in FIGS. 6 and 7, the magnetic fluxes A and B generated from the one winding 23 and the other winding 24 are separated by a closed magnetic circuit. Within the magnetic core 27, the common mode noise 29 is removed so as to be in the same direction as each other and to cancel each other out.

The center magnetic core 28 is a U-shaped magnetic core having a concave portion 32 with an open end portion 31. The concave portion 32 of the center magnetic core 28 is inserted into the center of the bobbin 22 to form the center magnetic core 28. One magnetic leg 25 of the closed magnetic path core 27 is arranged in the concave portion 32, and the tip 31 of the center magnetic core 28 and the other magnetic leg 26 of the closed magnetic path core 27 are arranged so as to face each other. I have.

At this time, the tip portion 31 of the center magnetic core 28
A first gap 33 is provided between the magnetic core 27 and the other magnetic leg 26 of the closed magnetic circuit core 27, and a concave portion 32 of the center magnetic core 28 is provided.
A second gap 35 is provided between the bottom surface 34 of the magnetic core 27 and the magnetic leg 25 of the closed magnetic circuit core 27, and the concave portion 32 of the center magnetic core 28 is provided.
Bottom surface 34 and inner side surface 36 are not in contact with one magnetic leg 25 of closed magnetic path magnetic core 27. The minimum dimension (X) of the first gap 33 is the minimum dimension of the second gap 35 provided between the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the one magnetic leg 25 of the closed magnetic path magnetic core 27. It is smaller than the dimension (Y).

Further, the cross-sectional shape of one magnetic leg 25 of the closed magnetic path core 27 is a polygonal octagon, and the one magnetic leg surface 37 of the closed magnetic path magnetic core 27 and the inner surface of the concave portion 32 of the center magnetic core 28. 36
Are arranged so that the width dimension of the concave portion 32 of the center magnetic core 28 is smaller than the maximum sectional width dimension (S) of the one magnetic leg portion 25.

Further, a through window 38 is provided at the center of the bobbin 22 facing the one magnetic leg 25 of the closed magnetic circuit core 27, and the inner side surface 36 of the recess 32 of the center core 28 is provided through the through window 38. And one magnetic leg 25 of the closed magnetic circuit core 27 are opposed to each other.

Then, the bobbin end faces at both ends of the through window 38 project outward from the end face of the through window 38,
The bobbin end face is set to the inner side face 36 of the concave portion 32 of the center magnetic core 28.
, So that the one magnetic leg 25 of the closed magnetic path magnetic core 27 and the inner side surface 36 of the concave portion 32 of the center magnetic core 28 are not in contact with each other.

At this time, the superposition current-inductance change rate of the common mode noise 29 and the normal mode noise 30 is as shown in FIG.

The operation of the above line filter will be described below.

With the above configuration, the first noise elimination means can eliminate the common mode noise 29, and the second noise elimination means can use the magnetic fluxes A and B generated from the one winding 23 and the other winding 24. To the center core 28 so as to be in the same direction as each other.
7 so that the magnetic fluxes A and B do not cancel each other out in the closed magnetic circuit core 27, the normal mode noise 30 can be removed, and the common mode noise 29 and the normal mode noise can be removed. Both of the noise 30 can be removed.

In particular, the center magnetic core 28 is a U-shaped magnetic core having a concave portion 32 with an open end portion 31, and the concave portion 32 of the center magnetic core 28 is inserted into the center of the bobbin 22, and the center magnetic core 28 is inserted. One magnetic leg 25 of the closed magnetic circuit core 27 is disposed in the recess 32 of the closed magnetic circuit core 27, and the end face 39 of the front end 31 of the center magnetic core 28 and the other magnetic leg 26
The first air gap 33 is provided between the tip 31 of the center magnetic core 28 and the other magnetic leg 26 of the closed magnetic core 27, and the center magnetic core 28 is provided. Since the bottom surface 34 and the inner side surface 36 of the concave portion 32 are not in contact with the one magnetic leg 25 of the closed magnetic circuit core 27, the magnetic saturation of the closed magnetic circuit core 27 is reduced when the common mode noise 29 is removed. Generation can be suppressed, the common mode noise 29 can be accurately removed, and the normal mode noise 30 can also be efficiently removed.

Since the second air gap 35 is provided between the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the one magnetic leg 25 of the closed magnetic circuit core 27, the normal mode noise 30
Can be further removed.

Further, the sectional shape of one magnetic leg 25 of the closed magnetic circuit core 27 is made polygonal, and the one magnetic leg surface 37 of the closed magnetic circuit core 27 and the inner side surface 36 of the concave portion 32 of the center magnetic core 28 are formed. Since the width dimension (T) of the concave portion 32 of the center magnetic core 28 is smaller than the maximum cross-sectional width dimension (S) of the one magnetic leg portion 25, the normal mode noise 30 Can be efficiently removed. In particular, if the half shape of the concave portion 32 of the center magnetic core 28 is made similar to the cross-sectional shape of the one magnetic leg portion 25 of the closed magnetic path magnetic core 27, the concave portion 32 of the center magnetic core 28 and one magnetic field of the closed magnetic path magnetic core 27 are formed. Since the leg 25 faces a wider area, there is no magnetic saturation or concentration of magnetic flux, and the normal mode noise 30
Can be efficiently removed.

Then, a through window 38 is provided at the center of the bobbin 22 facing the one magnetic leg 25 of the closed magnetic circuit core 27, and the inner surface 36 of the concave portion 32 of the center core 28 is formed through the through window 38. Since the one magnetic leg portion 25 of the closed magnetic circuit core 27 is opposed, the normal mode noise 30 can be further removed.

At this time, when the removing power of the normal mode noise 30 is large, the minimum dimension (X) of the first gap 33 is equal to the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and one of the closed magnetic circuit cores 27. By setting the second gap 35 provided between the magnetic leg 25 and the second gap 35 to be equal to or larger than the minimum dimension (Y), the rejection of the common mode noise 29 is not reduced and the rejection of the normal mode noise 30 is reduced. Can be done easily.

Further, the bobbin end faces at both ends of the through window 38 are made to protrude outward from the end face of the through window 38, and the bobbin end face is brought into contact with the inner side face 36 of the concave portion 32 of the center magnetic core 28, thereby closing the closed magnetic circuit. Since the one magnetic leg portion 25 of the core 27 and the inner side surface 36 of the concave portion 32 of the center magnetic core 28 are not in contact with each other, the center magnetic core 28 can be accurately positioned.

As described above, according to the first embodiment, the common mode noise 29 and the normal mode noise 30
Can be removed, and when the common mode noise 29 is removed, the occurrence of magnetic saturation of the closed magnetic circuit core 27 can be suppressed, and the common mode noise 29 can be properly removed. , Normal mode noise 30
Can also be efficiently removed.

When the removing power of the normal mode noise 30 is large, the minimum size (X) of the first void 33 is
Is a second gap 35 provided between the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the one magnetic leg 25 of the closed magnetic circuit core 27.
By making the minimum dimension (Y) or more, the ability to remove common mode noise can be easily reduced without impairing the ability to remove common mode noise.

Further, the center magnetic core 28 can be positioned accurately.

In the first embodiment, when the removing power of the normal mode noise 30 is large, the minimum dimension (X) of the first gap 33 is determined by the concave portion 32 of the center magnetic core 28.
Is larger than the minimum dimension (Y) of the second gap 35 provided between the bottom surface 34 of the magnetic core 27 and the one magnetic leg 25 of the closed magnetic circuit core 27, The second gap 35 provided between the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the one magnetic leg 25 of the closed magnetic core 27 has the minimum dimension (X) of the first gap 33. Can be reduced to the minimum dimension (Y) or less, and the rejection of the common mode noise 29 can be reduced without impairing the rejection of the normal mode noise 30.

In the first embodiment, the tip 31 of the center magnetic core 28 is connected to the other magnetic leg 26 of the closed magnetic core 27.
The inner side surface 36 and the end surface 39 of the distal end portion 31 are opposed to each other.
And the inner surface 36 of the distal end portion 31 may be opposed to each other. At this time, the ability to remove the common mode noise 29 can be reduced without impairing the ability to remove the normal mode noise 30.

Further, if a tapered portion is provided at the tip end portion 31 of the center magnetic core 28, and the tapered portion is provided such that the leading end thereof is separated from the other magnetic leg portions 26 of the closed magnetic circuit core 27, the center magnetic core is provided. The distance between the tapered portion 28 and the other magnetic leg 26 of the closed magnetic circuit core 27 can be finely adjusted, and the relationship between the power of removing the common mode noise 29 and the power of removing the normal mode noise 30 can be finely adjusted.

(Embodiment 2) Hereinafter, a line filter according to a second embodiment of the present invention will be described with reference to the drawings.

The line filter according to the second embodiment is an improvement of the line filter according to the first embodiment.

FIG. 9 is a perspective view of a line filter according to the second embodiment, FIG. 10 is a side sectional view of the line filter, and FIG. 11 shows a combined state of a closed magnetic path core and a center core of the line filter. FIG. 12 is a perspective view, FIG. 12 is a magnetic circuit diagram showing the flow of magnetic flux caused by normal mode noise of the line filter, and FIG. 13 is a magnetic circuit diagram showing the flow of magnetic flux caused by common mode noise of the line filter.

9 to 11, the line filter according to the second embodiment is different from the line filter according to the first embodiment in that the direction of the recess 32 of the center magnetic core 28 inserted into the center of the bobbin 22 is changed. The side surface portion 45 of the center magnetic core 28 and the other magnetic leg portion 26 of the closed magnetic circuit core 27 face each other, and the side surface portion 45 of the center magnetic core 28 and the other magnetic leg of the closed magnetic circuit core 27 are arranged. A first gap portion 33 is provided between the first gap portion 33 and the portion 26.

The minimum dimension (X) of the first gap 33 is
Is a second gap 35 provided between the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the one magnetic leg 25 of the closed magnetic circuit core 27.
Is the minimum dimension (Y) or more.

At this time, the second noise removing means operates as shown in FIG.
, The magnetic fluxes A and B generated from the one winding 23 and the other winding 24 are caused to flow in the center magnetic core 28 so as to be in the same direction as each other, and to the closed magnetic circuit core 27 in the opposite directions. The normal mode noise 30 is removed in the closed magnetic circuit core 27 so that the magnetic fluxes A and B do not cancel each other out, and the first noise removing means is the same as the conventional one. In the closed magnetic circuit core 27, the magnetic fluxes A and B generated from the one winding 23 and the other winding 24 are in the same direction as each other, and are mutually offset so as to eliminate common mode noise. ing.

With the above configuration, as in the first embodiment, both the common mode noise 29 and the normal mode noise 30 can be removed, and when the common mode noise 29 is removed, the closed magnetic circuit The occurrence of magnetic saturation of the core 27 can be suppressed, the common mode noise 29 can be accurately removed, and the normal mode noise 30 can be efficiently removed.

When the rejection of the common mode noise 29 is large, the minimum size of the first gap 33 is determined by the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the one magnetic leg 25 of the closed magnetic circuit core 27. Is smaller than the minimum dimension (Y) of the second gap 35 provided between the normal mode noise 3
0 can be easily reduced without impairing the power of removing the common mode noise 29.

In the second embodiment, when the power of removing the common mode noise 29 is large, the first gap 3
3 is equal to or less than the minimum dimension (Y) of the second gap 35 provided between the bottom surface 34 of the recess 32 of the center core 28 and the one magnetic leg 25 of the closed magnetic path core 27. However, when the removal power of the normal mode noise 30 is large, the minimum dimension (X) of the first gap 33 is set to be equal to the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the closed magnetic path magnetic core 27. By setting the second gap 35 provided between the magnetic leg 25 and the second gap 35 to a minimum dimension (Y) or more, the removability of the normal mode noise 30 can be reduced without impairing the rejection of the common mode noise 29. .

(Embodiment 3) Hereinafter, a line filter according to a third embodiment of the present invention will be described with reference to the drawings.

The line filter according to the third embodiment is an improvement of the line filter according to the first embodiment.

FIG. 14 is a perspective view of a line filter according to the third embodiment, FIG. 15 is a side sectional view of the line filter, and FIG. 16 shows a combined state of a closed magnetic path core and a center core of the line filter. FIG. 17 is a perspective view, FIG. 17 is a magnetic circuit diagram showing a flow of magnetic flux caused by normal mode noise of the line filter, and FIG. 18 is a magnetic circuit diagram showing a flow of magnetic flux caused by common mode noise of the line filter.

14 to 16, the line filter according to the third embodiment is different from the line filter according to the first embodiment in that the direction of the recess 32 of the center magnetic core 28 inserted into the center of the bobbin 22 is changed. And
The center magnetic core 28 is disposed such that the back surface 46 of the center magnetic core 28 and the other magnetic leg 26 of the closed magnetic circuit core 27 face each other.
The first air gap 33 is provided between the back surface portion 46 of the magnetic head 27 and the other magnetic leg portion 26 of the closed magnetic circuit core 27.

The minimum dimension (X) of the first gap 33
Is a second gap 35 provided between the bottom surface 34 of the concave portion 32 of the center magnetic core 28 and the one magnetic leg 25 of the closed magnetic circuit core 27.
Is smaller than the minimum dimension (Y).

At this time, the second noise removing means operates as shown in FIG.
, The magnetic fluxes A and B generated from the one winding 23 and the other winding 24 flow in the center magnetic core 28 so as to be in the same direction, and the magnetic fluxes A and B flow in the closed magnetic circuit core 27 in opposite directions. The normal mode noise 30 is removed so that the magnetic fluxes A and B do not cancel each other out in the closed magnetic circuit core 27, and the first noise removing means is the same as the conventional one, but FIG. In the closed magnetic circuit core 27, the magnetic fluxes A and B generated from the one winding 23 and the other winding 24 are in the same direction as each other, and are mutually offset so as to eliminate common mode noise. ing.

With the above configuration, as in the first embodiment, both the common mode noise 29 and the normal mode noise 30 can be removed, and when the common mode noise 29 is removed, the closed magnetic circuit The occurrence of magnetic saturation of the core 27 can be suppressed, the common mode noise 29 can be accurately removed, and the normal mode noise 30 can be efficiently removed.

When the power of removing the common mode noise 29 is large, the minimum dimension (X) of the first gap 33 is:
The bottom surface 34 of the concave portion 32 of the center core 28 and the closed magnetic core 2
7 is not more than the minimum size (Y) of the second gap 35 provided between the common mode noise 30 and the common mode noise 29.
Can easily be reduced.

In the third embodiment, when the power of removing the common mode noise 29 is large, the first gap 3
3 is equal to or less than the minimum dimension (Y) of the second gap 35 provided between the bottom surface 34 of the recess 32 of the center core 28 and the one magnetic leg 25 of the closed magnetic path core 27. However, if the rejection of normal mode noise is large,
The minimum dimension (X) of the first gap 33 is determined by the center core 2
8 and one magnetic leg 2 of the closed magnetic circuit core 27
By setting the second gap 35 provided between the second gap 5 and the second gap 5 to be equal to or more than the minimum dimension (Y), it is also possible to reduce the removability of the normal mode noise 30 without impairing the removability of the common mode noise 29.

(Embodiment 4) Hereinafter, a line filter according to a fourth embodiment of the present invention will be described with reference to the drawings.

The line filter according to the fourth embodiment is an improvement of the line filter according to the first embodiment.

FIG. 19 is a perspective view of a line filter according to the fourth embodiment, FIG. 20 is a side sectional view of the line filter, and FIG. 21 shows a combined state of a closed magnetic path core and a center core of the line filter. FIG. 22 is a perspective view, FIG. 22 is a magnetic circuit diagram showing the flow of magnetic flux caused by normal mode noise of the line filter, and FIG. 23 is a magnetic circuit diagram showing the flow of magnetic flux caused by common mode noise of the line filter.

19 to 21, the line filter according to the fourth embodiment is the same as the line filter according to the first embodiment except that the closed magnetic circuit core 27 is changed from a square shape to a sun shape. It is.

At this time, the second noise removing means operates as shown in FIG.
, The magnetic fluxes A and B generated from the one winding 23 and the other winding 24 are caused to flow in the center magnetic core 28 so as to be in the same direction as each other, and to the closed magnetic circuit core 27 in the opposite directions. 23, the normal mode noise 30 is removed in the closed magnetic circuit core 27 so that the magnetic fluxes A and B do not cancel each other, and the first noise removing means is the same as the conventional one. , The common mode noise 29 is removed by making the magnetic fluxes A and B generated from the one winding 23 and the other winding 24 in the closed magnetic circuit core 27 in the same direction as each other and cancel each other out. are doing.

Furthermore, the side surface portion 47 of the center magnetic core 28 and the other magnetic leg portion 26 of the closed magnetic circuit core 27 are arranged so as to face each other.

With the above configuration, as in the first embodiment, both the common mode noise 29 and the normal mode noise 30 can be removed, and when the common mode noise 29 is removed, the closed magnetic circuit The occurrence of magnetic saturation of the core 27 can be suppressed, the common mode noise 29 can be accurately removed, and the normal mode noise 30 can be efficiently removed.

When the power of removing the common mode noise 29 is large, the minimum dimension (X) of the first gap 33 is
The bottom surface 34 of the concave portion 32 of the center core 28 and the closed magnetic core 2
7 is not more than the minimum size (Y) of the second gap 35 provided between the common mode noise 30 and the common mode noise 29.
Can easily be reduced.

In the fourth embodiment, the side surface portion 47 of the center magnetic core 28 and the other magnetic leg portion 26 of the closed magnetic circuit core 27 are disposed so as to face each other. Similar effects can be obtained by changing the direction of the concave portion 32 of the center magnetic core 28 inserted into the center of the bobbin 22 as in the embodiment or the third embodiment.

[0118]

As described above, according to the present invention, the first noise removing means can remove the common mode noise, and the second noise removing means generates the common mode noise from one winding and the other winding. In the closed magnetic circuit core, the magnetic fluxes flow in the center magnetic core in the same direction as each other, and in the closed magnetic circuit core in opposite directions. Modal noise can be removed.

Therefore, it is possible to provide a line filter that removes both the common mode noise and the normal mode noise.

In particular, the center magnetic core is a U-shaped magnetic core having a concave portion having an open end, and the concave portion of the center magnetic core is inserted into the center of the bobbin, so that the closed magnetic path magnetic core is formed in the concave portion of the center magnetic core. One magnetic leg of the core is arranged, and the tip of the center magnetic core and the other magnetic leg of the closed magnetic path core are arranged to face each other. The first air gap is provided between the magnetic core and the leg, and the bottom surface and the inner surface of the concave portion of the center magnetic core are not in contact with one magnetic leg of the closed magnetic core. In addition, the occurrence of magnetic saturation of the closed magnetic circuit core can be suppressed, and common mode noise can be accurately removed.
Normal mode noise can also be efficiently removed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a line filter according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the line filter.

FIG. 3 is a perspective view showing a combined state of a closed magnetic core and a center magnetic core of the line filter.

FIG. 4 is a magnetic circuit diagram showing a magnetic flux flow caused by normal mode noise of the line filter.

FIG. 5 is an electric circuit diagram showing propagation of normal mode noise when the line filter is used.

FIG. 6 is a magnetic circuit diagram showing a flow of magnetic flux caused by common mode noise of the line filter.

FIG. 7 is an electric circuit diagram showing propagation of common mode noise when the line filter is used.

FIGS. 8A and 8B are characteristic diagrams showing superimposed current-inductance change rates of common mode noise and normal mode noise, respectively.

FIG. 9 is a perspective view of a line filter according to a second embodiment.

FIG. 10 is a side sectional view of the line filter.

FIG. 11 is a perspective view showing a combined state of a closed magnetic circuit core and a center magnetic core of the line filter.

FIG. 12 is a magnetic circuit diagram showing the flow of magnetic flux caused by normal mode noise of the line filter.

FIG. 13 is a magnetic circuit diagram showing a flow of a magnetic flux caused by common mode noise of the line filter.

FIG. 14 is a perspective view of a line filter according to a third embodiment.

FIG. 15 is a side sectional view of the line filter.

FIG. 16 is a perspective view showing a combined state of a closed magnetic path core and a center core of the line filter.

FIG. 17 is a magnetic circuit diagram showing a magnetic flux flow caused by normal mode noise of the line filter.

FIG. 18 is a magnetic circuit diagram showing the flow of magnetic flux caused by common mode noise of the line filter.

FIG. 19 is a perspective view of a line filter according to a fourth embodiment.

FIG. 20 is a side sectional view of the line filter.

FIG. 21 is a perspective view showing a combined state of a closed magnetic core and a center magnetic core of the line filter.

FIG. 22 is a magnetic circuit diagram showing a flow of a magnetic flux caused by normal mode noise of the line filter.

FIG. 23 is a magnetic circuit diagram showing the flow of magnetic flux caused by common mode noise of the line filter.

FIG. 24 is a perspective view of a conventional line filter.

FIG. 25 is a front sectional view of the line filter.

FIG. 26 is an electric circuit diagram showing propagation of common mode noise when the line filter is used.

FIG. 27 is a magnetic circuit diagram showing the flow of magnetic flux caused by common mode noise of the line filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Through-hole 22 Bobbin 23 One winding 24 The other winding 25 One magnetic leg 26 Other magnetic leg 27 Closed magnetic circuit core 28 Center magnetic core 29 Common mode noise 30 Normal mode noise 31 Tip 32 Depression 33 First Void 34 bottom surface 35 second void portion 36 inner surface 37 one magnetic leg surface 38 through window 39 end surface 40 inner surface 41 side surface 45 side surface 46 back surface 47 side surface

Claims (26)

[Claims] 1. A bobbin having a through hole, one winding and the other winding wound around the bobbin, and one magnetic leg inserted into the through hole of the bobbin, and the one magnetic leg And a center disposed at the center of the bobbin so as to be positioned between the one winding and the other winding so that the other magnetic leg facing the other is disposed outside the through hole. A magnetic core, first noise removing means for removing common mode noise, and second noise removing means for removing normal mode noise, wherein the center magnetic core has a U-shape having a concave portion with an open end. A magnetic core, a concave portion of the center magnetic core is inserted into a center portion of the bobbin, and one magnetic leg of the closed magnetic circuit core is disposed in the concave portion of the center magnetic core; And the other magnetic leg of the closed magnetic circuit core A first gap is provided between the tip of the center magnetic core and the other magnetic leg of the closed magnetic circuit core, and the bottom surface and the inner side surface of the concave portion of the center magnetic core are arranged so as to face each other. The magnetic flux generated from the one winding and the other winding is applied to the center magnetic core in the same direction as the magnetic flux generated by the one winding and the other winding by bringing the magnetic flux generated from the one winding and the other winding out of contact with the one magnetic leg of the closed magnetic circuit core. And a line as means for removing normal mode noise by allowing the magnetic fluxes to cancel each other out in the closed magnetic path core, while flowing in opposite directions to the closed magnetic path core. filter. 2. The line filter according to claim 1, wherein a second gap is provided between a bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic circuit core. 3. A cross-sectional shape of one magnetic leg of the closed magnetic path core is polygonal, and a surface of the one magnetic leg of the closed magnetic path core and an inner surface of a concave portion of the center magnetic core are opposed to each other. 2. The line filter according to claim 1, wherein the width dimension of the concave portion of the center magnetic core is smaller than the maximum sectional width dimension of the one magnetic leg portion. 4. The line filter according to claim 1, wherein a half shape of the concave portion of the center magnetic core is similar to a cross-sectional shape of one magnetic leg portion of the closed magnetic path magnetic core. 5. A penetrating window is provided at a central portion of a bobbin opposed to one magnetic leg of a closed magnetic circuit core, and an inner side surface of a concave portion of a center magnetic core and one of the closed magnetic circuit cores are provided through the through window. The line filter according to claim 1, wherein the magnetic leg portion is opposed to the magnetic leg portion. 6. A bobbin end face at both ends of a through window is projected outward from an end face of said through window, and said bobbin end face is brought into contact with an inner side face of a concave portion of a center magnetic core. 6. The line filter according to claim 5, wherein the magnetic leg portion and the inner side surface of the concave portion of the center core are not in contact with each other. 7. The line filter according to claim 1, wherein the minimum size of the first gap is equal to or larger than the minimum size between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core. 8. The line filter according to claim 1, wherein the minimum size of the first gap is equal to or less than the minimum size between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core. 9. The line filter according to claim 1, wherein a front end of the center magnetic core faces a side surface of another magnetic leg portion of the closed magnetic path magnetic core. 10. The line filter according to claim 1, wherein a tapered portion is provided at a tip portion of the center magnetic core, and the tapered portion is provided such that a tip thereof is separated from another magnetic leg of the closed magnetic circuit core than a root. 11. A bobbin having a through-hole, a winding wound around the bobbin, and another magnetic leg inserted into the through-hole of the bobbin and facing the one magnetic leg. , A closed magnetic path core disposed outside the through hole, a center core disposed in the center of the bobbin, first noise removing means for removing common mode noise, and second noise for removing normal mode noise. Removing means, wherein the center magnetic core is a U-shaped magnetic core having a concave portion with an open end, and the concave portion of the center magnetic core is inserted into the center of the bobbin to form a concave portion of the center magnetic core. The one magnetic leg of the closed magnetic path core is disposed inside, and the side surface of the center magnetic core is disposed so as to face the other magnetic leg of the closed magnetic path core, and the side surface of the center magnetic core is disposed. Part and the other magnetic leg of the closed magnetic circuit core A first gap is provided therebetween, and the bottom surface and the inner side surface of the concave portion of the center magnetic core are brought into non-contact with one magnetic leg of the closed magnetic core. A magnetic flux generated from the wire and the other winding is caused to flow in the center magnetic core in the same direction as each other, and to the closed magnetic core in a direction opposite to each other. A line filter as means for removing normal mode noise by making the magnetic fluxes cancel each other. 12. A second gap portion is provided between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic path magnetic core.
The line filter according to 1. 13. A cross-sectional shape of one magnetic leg of the closed magnetic path core is polygonal, and the surface of the one magnetic leg of the closed magnetic path core and the inner surface of the concave portion of the center magnetic core are opposed to each other. The line filter according to claim 11, wherein the width dimension of the concave portion of the center magnetic core is smaller than the maximum cross-sectional width dimension of the one magnetic leg portion. 14. A half shape of a concave portion of a center magnetic core is made similar to a cross-sectional shape of one magnetic leg of a closed magnetic circuit magnetic core.
The line filter according to 1. 15. A penetrating window is provided at a central portion of a bobbin opposed to one magnetic leg of a closed magnetic circuit core, and an inner side surface of a concave portion of a center magnetic core and one of the closed magnetic circuit cores are provided through the through window. The line filter according to claim 11, wherein the magnetic leg portion is opposed to the magnetic leg portion. 16. A bobbin end face at both ends of the through window is projected outward from an end face of the through window, and the bobbin end face is brought into contact with an inner side face of a concave portion of the center magnetic core to form one end of the closed magnetic path magnetic core. 16. The line filter according to claim 15, wherein a magnetic leg and the inner side surface of the concave portion of the center magnetic core are not in contact with each other. 17. The line filter according to claim 11, wherein the minimum size of the first gap is equal to or greater than the minimum size between the inner surface of the recess of the center magnetic core and one magnetic leg of the closed magnetic core. 18. The line filter according to claim 11, wherein the minimum size of the first gap is equal to or smaller than the minimum size between the inner surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core. 19. A bobbin having a through-hole, a winding wound around the bobbin, and another magnetic leg inserted into the through-hole of the bobbin and facing the one magnetic leg. , A closed magnetic path core disposed outside the through hole, a center core disposed in the center of the bobbin, first noise removing means for removing common mode noise, and second noise for removing normal mode noise. Removing means, wherein the center magnetic core is a U-shaped magnetic core having a concave portion with an open end, and the concave portion of the center magnetic core is inserted into the center of the bobbin to form a concave portion of the center magnetic core. A magnetic leg of the closed magnetic path core is disposed inside the magnetic core, and a rear surface of the center magnetic core is disposed so as to face another magnetic leg of the closed magnetic path core; Part and the other magnetic leg of the closed magnetic circuit core A first gap is provided therebetween, and the bottom surface and the inner side surface of the concave portion of the center magnetic core are brought into non-contact with one magnetic leg of the closed magnetic core. A magnetic flux generated from the wire and the other winding is caused to flow in the center magnetic core in the same direction as each other, and to the closed magnetic core in a direction opposite to each other. A line filter as means for removing normal mode noise by making the magnetic fluxes cancel each other. 20. A second gap is provided between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic path magnetic core.
The line filter according to 1. 21. A cross-sectional shape of one magnetic leg of the closed magnetic core is made polygonal, and a surface of the one magnetic leg of the closed magnetic core and an inner surface of a concave portion of the center magnetic core are opposed to each other. 20. The line filter according to claim 19, wherein the width of the concave portion of the center magnetic core is smaller than the maximum cross-sectional width of the one magnetic leg. 22. The half shape of the concave portion of the center magnetic core is similar to the cross-sectional shape of one magnetic leg of the closed magnetic core.
The line filter according to 1. 23. A penetrating window is provided at a central portion of a bobbin facing one magnetic leg of a closed magnetic circuit core, and an inner side surface of a concave portion of a center magnetic core and one of the closed magnetic circuit cores are provided through the through window. 20. The line filter according to claim 19, wherein the magnetic leg portion is opposed to the magnetic leg portion. 24. A bobbin end face at each end of the through window is projected outward from an end face of the through window, and the bobbin end face is brought into contact with an inner side face of a recess of the center magnetic core to form one end of the closed magnetic circuit core. 24. The line filter according to claim 23, wherein the magnetic leg portion and the inner side surface of the concave portion of the center core are not in contact with each other. 25. The line filter according to claim 19, wherein the minimum size of the first gap is equal to or larger than the minimum size between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core. 26. The line filter according to claim 19, wherein the minimum size of the first gap is equal to or smaller than the minimum size between the bottom surface of the concave portion of the center magnetic core and one magnetic leg of the closed magnetic core.