JP2023071390A - Noise filter and cable with noise filter - Google Patents

Abstract

To provide a noise filter with a magnetic body core that is made smaller in outer diameter than conventional articles although made equal to or larger in inner diameter and magnetic characteristics than the conventional articles.SOLUTION: A noise filter has a cylindrical magnetic body core made of soft magnetic metal foil. The soft magnetic metal foil is wound around a space serving as a bore of a magnetic core with a thickness of the soft magnetic metal foil directed to a diameter of the magnetic body core to be laminated in a diameter direction of the magnetic body core. The soft magnetic metal foil is 12 to 26 μm. The magnetic body core is axially 50 to 150 mm long. A radial thickness of the magnetic body core which is the distance between an outer peripheral surface and an inner peripheral surface of the magnetic body core is 1 to 5 mm.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to noise filters and cables with noise filters.

A noise filter having an annular magnetic core is known (see Patent Document 1, for example). The magnetic core described in Patent Document 1 is made of a nanocrystalline soft magnetic material. The nanocrystalline soft magnetic material referred to in Patent Document 1 is a material in which nanocrystalline grains of a ferromagnetic phase are dispersed in the remaining amorphous phase by crystallizing an amorphous alloy.

Japanese Patent No. 6311847

When attaching a magnetic core to a cable, if there is not enough space in the radial direction of the magnetic core, it may be desirable to use a magnetic core with a smaller diameter. However, it is not easy to reduce the outer diameter of the magnetic core while maintaining the functions and performance required for the noise filter.

For example, when reducing the outer diameter of the magnetic core, the thickness of the magnetic core in the radial direction is reduced unless the inner diameter of the magnetic core is changed. In this case, the magnetic properties of the magnetic core may deteriorate, and the performance as a noise filter may deteriorate.

Further, for example, by reducing the inner diameter of the magnetic core by the amount corresponding to the reduction in the outer diameter of the magnetic core, it is possible to suppress the thickness of the magnetic core from being thinned in the radial direction. However, when the inner diameter of the magnetic core is reduced, the upper limit of the diameter and the number of wires that can be inserted through the magnetic core becomes smaller, and it becomes impossible to attach to wires or wire bundles that exceed the upper limits.

In one aspect of the present disclosure, a noise filter comprising a magnetic core having an outer diameter smaller than that of a conventional product, although the inner diameter and magnetic characteristics are equal to or higher than those of a conventional product; It would be desirable to provide a noise-filtered cable with an excellent noise filter.

One aspect of the present disclosure is a noise filter having a cylindrical magnetic core made of soft magnetic metal foil. The soft magnetic metal foil is wound around the space serving as the inner cavity of the magnetic core in a state in which the thickness direction of the soft magnetic metal foil is oriented in the radial direction of the magnetic core. Laminated radially. The soft magnetic metal foil has a thickness of 12 μm to 26 μm. The axial length of the magnetic core is set to 50 mm to 150 mm. The radial thickness of the magnetic core, which is the distance between the outer peripheral surface and the inner peripheral surface of the magnetic core, is set to 1 mm to 5 mm.

According to the noise filter configured in this way, the radial thickness of the magnetic core is set to 1 mm to 5 mm. Therefore, the outer diameter of the magnetic core can be reduced even if the inner diameter of the magnetic core is kept equal to that of the conventional product.

Further, the axial length of the magnetic core is set to 50 mm or more. Therefore, unlike conventional products in which the axial length of the magnetic core is equal to or less than the radial thickness of the magnetic core, the magnetic core has a thin radial thickness. Regardless, the magnetic properties of the magnetic core can be made equal to or better than those of conventional products.

Therefore, if the magnetic core as described above is used, the magnetic core is provided with a smaller outer diameter than the conventional product, although the inner diameter and magnetic properties are equal to or higher than those of the conventional product. A noise filter can be provided.

Note that the noise filter of the present disclosure may be further configured as follows.
(A) The outer diameter of the magnetic core may be 12 mm to 50 mm.
(B) The soft magnetic metal foil may be a nanocrystalline alloy foil formed by subjecting an Fe-based amorphous alloy foil to heat treatment in a magnetic field.

(C) configured to be attachable to a cable having an electric wire or electric wire bundle and a braid covering the outer periphery of the electric wire or electric wire bundle, and when attached to the cable, the magnetic core is attached to the electric wire or It may be arranged at a location on the outer peripheral side of the wire bundle and the inner peripheral side of the braid.

Another aspect of the present disclosure is a cable with a noise filter. A cable with a noise filter includes a cable and a noise filter. A noise filter is attached to the cable. A cable comprises a wire or wire bundle and a braid. The braid covers the outer circumference of the wire or wire bundle. The noise filter has a cylindrical magnetic core made of soft magnetic metal foil. The soft magnetic metal foil is wound around the space serving as the inner cavity of the magnetic core in a state in which the thickness direction of the soft magnetic metal foil is oriented in the radial direction of the magnetic core. Laminated radially. The soft magnetic metal foil has a thickness of 12 μm to 26 μm. The axial length of the magnetic core is set to 50 mm to 150 mm. The radial thickness of the magnetic core, which is the distance between the outer peripheral surface and the inner peripheral surface of the magnetic core, is set to 1 mm to 5 mm. A magnetic core is arranged on the outer peripheral side of the wire or wire bundle and the inner peripheral side of the braid.

According to the cable with a noise filter configured in this way, the noise filter has the same configuration as the noise filter of one aspect of the present disclosure, so the operation as described for the noise filter of one aspect of the present disclosure, Effective.

FIG. 1A is a perspective view showing the noise filter of the embodiment. FIG. FIG. 1B is a perspective view showing a conventional noise filter. FIG. 2 is a graph showing characteristics of the noise filter of the embodiment and a conventional noise filter. FIG. 3 is a schematic diagram showing a cable with noise filter according to the embodiment.

Next, exemplary embodiments of the noise filter and the cable with the noise filter described above will be described.
[Composition of noise filter]
As shown in FIG. 1A, a noise filter 1 exemplified as an embodiment of the present disclosure has a tubular magnetic core 3 . The magnetic core 3 is made of soft magnetic metal foil. Although the microscopic structure of the magnetic core 3 does not appear in FIG. It is wound around the space that becomes the inner cavity of the magnetic core 3 in such a state that it is held in place. Thus, the soft magnetic metal foils forming the magnetic core 3 are laminated in the radial direction of the magnetic core 3 .

The thickness of the soft magnetic metal foil may be set to a thickness that does not cause any inconvenience in configuring the magnetic core 3, but if a more specific numerical range is exemplified, for example, the thickness of the soft magnetic metal foil is preferably configured to be approximately 12 μm to 26 μm. In this embodiment, the soft magnetic metal foil has a thickness of 17 μm.

The axial length L1 of the magnetic core 3 is longer than the axial length L2 of the magnetic core 93 (see FIG. 1B) included in the conventional noise filter 91 . As an example of a more specific numerical range, for example, the axial length L1 of the magnetic core 3 is preferably set to approximately 50 mm to 150 mm. In this embodiment, the axial length L1 of the magnetic core 3 is set to 142 mm. In the case of the magnetic core 93 included in the conventional noise filter 91, the axial length L2 is generally configured to be approximately 10 mm to 50 mm.

The outer diameter D1 of the magnetic core 3 is smaller than that of the magnetic core 93 included in the conventional noise filter 91 . As an example of a more specific numerical range, for example, the outer diameter D1 of the magnetic core 3 is preferably configured to be approximately 12 mm to 50 mm. In this embodiment, the outer diameter D1 of the magnetic core 3 is set to 24 mm. In the case of the magnetic core 93 included in the conventional noise filter 91, the outer diameter D2 of the magnetic core 93 is generally set to approximately 10 mm to 50 mm. In the case of the magnetic core 93 illustrated in FIG. 1B, the outer diameter D2 of the magnetic core 93 is set to 30 mm.

The inner diameter d1 of the magnetic core 3 is approximately the same as the inner diameter d2 of the magnetic core 93 included in the conventional noise filter 91 . As an example of a more specific numerical range, for example, it is preferable that the inner diameter d1 of the magnetic core 3 is configured to be approximately 10 mm to 48 mm. In this embodiment, the inner diameter d1 of the magnetic core 3 is set to 20 mm. In addition, in the case of the magnetic core 93 illustrated in FIG. 1B, the inner diameter d2 of the magnetic core 93 is configured to be 20 mm.

Since the outer diameter D1 and the inner diameter d1 of the magnetic core 3 are configured as described above, the radial thickness of the magnetic core 3 is configured to be thinner than the magnetic core 93 included in the conventional noise filter 91. It means that The thickness of the magnetic core 3 in the radial direction here is the distance (D1−d1)/2 between the outer peripheral surface and the inner peripheral surface of the magnetic core 3 . As an example of a more specific numerical range, for example, it is preferable that the radial thickness of the magnetic core 3 is configured to be approximately 1 mm to 5 mm. In this embodiment, the radial thickness of the magnetic core 3 is set to 2 mm. In the case of the magnetic core 93 included in the conventional noise filter 91, the thickness in the radial direction of the magnetic core 3 is generally configured to be approximately 4 mm to 20 mm. In the case of the magnetic core 93 illustrated in FIG. 1B, the radial thickness of the magnetic core 93 is set to 5 mm.

In this embodiment, a nanocrystalline alloy foil is used as the soft magnetic metal foil forming the magnetic core 3 . In this embodiment, the nanocrystalline alloy foil is an Fe-based amorphous alloy foil (in atomic %, Cu: 1.4%, Nb: 7.3%, Si: 8.4%, B: 1.4% , Fe and unavoidable impurities.) are subjected to heat treatment in a magnetic field to nanocrystallize a part of the Fe-based amorphous alloy.

More specifically, in the case of this embodiment, the magnetic core 3 is configured by the procedure described below. First, a strip (width: 142 mm, thickness: 17 μm) made of an Fe-based amorphous alloy foil is wound around an axis parallel to the width direction of the strip to form a Fe-based amorphous alloy cylindrical body. . This cylindrical body is placed in a magnetic field heat treatment furnace and subjected to magnetic field heat treatment. Specifically, the temperature in the furnace is raised to a temperature equal to or higher than the crystallization start temperature of the Fe-based amorphous alloy while applying a magnetic field to the cylindrical body of the Fe-based amorphous alloy placed in the furnace, Precipitate nanocrystals in the alloy.

The temperature equal to or higher than the crystallization starting temperature of the Fe-based amorphous alloy is, for example, 500° C. or higher. However, a temperature that can suppress the growth of precipitated crystals to several hundred nanometers or more is preferable, and for example, 700° C. or less is preferable. After the magnetic field heat treatment is completed, the temperature in the furnace is slowly lowered in order to prevent the belt-shaped body forming the cylindrical body from being damaged by rapid cooling. As a result, the magnetic core 3 made of the Fe-based nanocrystalline alloy foil can be obtained.

The obtained magnetic core 3 can be used alone as the noise filter 1 . However, the noise filter 1 may be configured in combination with other members not shown in FIG. 1A. Examples of other members include a case made of resin, for example. In this case, the noise filter 1 may be constructed by housing the magnetic core 3 in the case. Alternatively, examples of other members include a coating layer covering the surface of the magnetic core 3. In this case, the magnetic core 3 is coated with a coating composition, and the coating composition is cured. The noise filter 1 may be configured by the above.

[Noise filter performance evaluation]
In order to evaluate the performance of the noise filter 1, the impedance characteristics of the magnetic core 3 (hereinafter also referred to as the magnetic core 3 of the embodiment) were measured. For comparison, the impedance characteristics of the magnetic core 93 included in the conventional noise filter 91 (hereinafter also referred to as the magnetic core 93 of the comparative example) were measured. A commercially available network analyzer (manufactured by Agilent Technologies, model number: E5061B) was used to measure the impedance characteristics.

Specifically, the operation mode of the network analyzer was set to the impedance measurement mode. A copper wire (diameter 0.5 mm, length 300 mm) is passed through the inner peripheral side of the magnetic core 3, both ends of the copper wire are fixed to the connection terminals of the test fixture, and the impedance of the magnetic core 3 is measured by a single method. properties were measured. The measurement was performed in a normal temperature (25°C) environment. Further, the magnetic core 93 of the comparative example was used in place of the magnetic core 3 of the example, and the impedance characteristics of the magnetic core 93 were measured in the same manner as in the example except that. The measurement results are shown in FIG.

From the measurement results shown in FIG. 2, it has become clear that the magnetic core 3 of the example exhibits higher impedance characteristics than the magnetic core 93 of the comparative example in the frequency band from 0.1 MHz to 10 MHz. That is, although the magnetic core 3 of the example has a smaller radial thickness and a smaller outer diameter than the magnetic core 93 of the comparative example, the magnetic core 93 of the comparative example shows higher impedance characteristics than

Therefore, with the noise filter 1 having such a magnetic core 3, it is possible to reduce the outer diameter while maintaining performance as a noise filter better than that of the conventional product. Therefore, when attaching the noise filter 1 to the cable, the noise filter 1 can be attached even if there is not enough space in the radial direction of the magnetic core 3 .

[Configuration of cable with noise filter]
Next, a noise filter cable 10 (see FIG. 3) having the noise filter 1 described above will be described. The cable with noise filter 10 includes a cable 11 and a noise filter 1 attached to the cable 11, as illustrated in FIG. The cable 11 includes an electric wire bundle 13 and a braid 15 covering the outer circumference of the electric wire bundle 13 . A connector 17 is attached to one end of the cable 11 .

In the case of this embodiment, the wire bundle 13 has two wires 13P and 13N used as DC power supply lines (PN lines). Further, in the case of this embodiment, the braid 15 is composed of a plurality of metal wires woven into a tubular shape, and electromagnetic waves are transmitted from one side to the other between the inner peripheral side and the outer peripheral side of the braid 15. It functions as an electromagnetic wave shield material that blocks propagation.

A noise filter 1 has a magnetic core 3 . FIG. 3 shows an example in which the magnetic core 3 is used alone as the noise filter 1 . However, as already explained, the noise filter 1 may be configured by combining the magnetic core 3 and other members (for example, a case, a coating layer, etc.). The magnetic core 3 is arranged on the outer peripheral side of the wire bundle 13 and the inner peripheral side of the braid 15 .

As already described, the magnetic core 3 has a smaller radial thickness and a smaller outer diameter than the conventional magnetic core 93 . Therefore, even if the magnetic core 3 is arranged on the inner peripheral side of the braid 15, the diameter of the outer circumference of the braid 15 is not increased as compared with the case where the conventional magnetic core 93 is arranged at the same location. can be suppressed. Moreover, as described above, since the magnetic core 3 exhibits higher impedance characteristics than the conventional magnetic core 93, the noise filter cable 10 provided with the noise filter 1 having such a magnetic core 3 Thus, compared to the case where the conventional noise filter 91 is provided, the noise reduction effect for noise propagating through the cable 11 can be enhanced.

[Other embodiments]
As described above, the noise filter and the cable with the noise filter have been described with reference to exemplary embodiments, but the above-described embodiments are merely examples as one aspect of the present disclosure. That is, the present disclosure is not limited to the exemplary embodiments described above, and can be embodied in various forms without departing from the technical spirit of the present disclosure.

For example, in the above embodiment, as an example of the soft magnetic metal foil, a nanocrystalline alloy foil having a specific component ratio was exemplified. However, if the nanocrystalline alloy foil can be used as a magnetic core, the component ratio It is not limited to the above examples. Also, the soft magnetic metal foil is not limited to the nanocrystalline alloy foil. For example, the amorphous alloy foil exemplified in the above embodiments may be used. Specifically, in the above embodiment, an example of forming a nanocrystalline alloy foil by subjecting the amorphous alloy foil to heat treatment in a magnetic field was shown, but the heat treatment in the magnetic field is omitted and the amorphous alloy foil is used as it is. You may Alternatively, soft magnetic metal foils other than nanocrystalline alloy foils and amorphous alloy foils may be employed.

Further, in the cable 10 with a noise filter illustrated in the above embodiment, the magnetic core 3 included in the noise filter 1 is arranged on the outer peripheral side of the wire bundle 13 and the inner peripheral side of the braid 15. The noise filter 1 may be arranged at the position of . For example, the noise filter 1 may be arranged on the outer peripheral side of the braid 15 .

In addition, in the cable 10 with noise filter illustrated in the above embodiment, the braid 15 is composed of a plurality of metal wires braided into a tubular shape, but the material composing the braid 15 is not limited to metal. For example, when the braid 15 is to function as an electromagnetic wave shielding material as in the above embodiment, the braid 15 is preferably made of a metal wire. On the other hand, if the braid 15 is to function as a reinforcing material for protecting the wire bundle 13 when an external force acts on the cable 11, the braid 15 is made of synthetic resin fiber (for example, polyester fiber, etc.) or glass fiber. may have been Alternatively, the braid 15 may be configured by combining a metal wire and fibers other than the metal wire.

A plurality of functions realized by one component illustrated in the above embodiment may be realized by a plurality of components. One function realized by one component exemplified in the above embodiments may be realized by a plurality of components. A plurality of functions realized by a plurality of components illustrated in the above embodiments may be realized by a single component. One function realized by a plurality of components illustrated in the above embodiments may be realized by one component. A part of the configuration illustrated in the above embodiment may be omitted.

Reference Signs List 1, 91 noise filter, 3, 93 magnetic core, 10 cable with noise filter, 11 cable, 13 wire bundle, 13P, 13N wire, 15 braid.

Claims (5)

Having a cylindrical magnetic core made of soft magnetic metal foil,
The soft magnetic metal foil is wound around a space serving as a lumen of the magnetic core in a state in which the thickness direction of the soft magnetic metal foil is oriented in the radial direction of the magnetic core. Laminated in the radial direction of the magnetic core,
The soft magnetic metal foil has a thickness of 12 μm to 26 μm,
The magnetic core has an axial length of 50 mm to 150 mm,
The radial thickness of the magnetic core, which is the distance between the outer peripheral surface and the inner peripheral surface of the magnetic core, is 1 mm to 5 mm.
Noise filter. The noise filter according to claim 1,
The magnetic core has an outer diameter of 12 mm to 50 mm,
Noise filter. The noise filter according to claim 1 or claim 2,
The soft magnetic metal foil is a nanocrystalline alloy foil formed by subjecting an Fe-based amorphous alloy foil to heat treatment in a magnetic field,
Noise filter. A noise filter according to any one of claims 1 to 3,
It is configured to be attachable to a cable having an electric wire or electric wire bundle and a braid covering the outer periphery of the electric wire or electric wire bundle, and when attached to the cable, the magnetic core is attached to the electric wire Or arranged on the outer peripheral side of the wire bundle and the inner peripheral side of the braid,
Noise filter. a cable;
a noise filter attached to the cable;
with
The cable is
a wire or wire bundle;
a braid covering the outer periphery of the electric wire or electric wire bundle;
with
The noise filter is
Having a cylindrical magnetic core made of soft magnetic metal foil,
The soft magnetic metal foil is wound around a space serving as a lumen of the magnetic core in a state in which the thickness direction of the soft magnetic metal foil is oriented in the radial direction of the magnetic core. Laminated in the radial direction of the magnetic core,
The soft magnetic metal foil has a thickness of 12 μm to 26 μm,
The magnetic core has an axial length of 50 mm to 150 mm,
The radial thickness of the magnetic core, which is the distance between the outer peripheral surface and the inner peripheral surface of the magnetic core, is 1 mm to 5 mm,
The magnetic core is arranged on the outer peripheral side of the electric wire or electric wire bundle and the inner peripheral side of the braid,
Cable with noise filter.

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