JP7729793B2 - Noise reduction device and wire harness - Google Patents

Description

The present invention relates to a noise reduction device and a wire harness.

Noise reduction devices are components made of magnetic materials and are attached to electric wires carrying noise currents to reduce the external emission of radiated noise from the wires. For example, a noise reduction device may include two semi-cylindrical magnetic bodies (so-called ferrite cores) that are combined to form a cylindrical shape, with the electric wire inserted into the internal space. However, noise reduction devices that utilize such magnetic bodies are difficult to use with electric wires of significantly different diameters, and even the use of components that can be shared between electric wires of significantly different diameters is difficult. For this reason, this technical field desires a noise reduction device whose components can be shared between electric wires of different diameters. For example, Patent Document 1 listed below discloses a chain-structured noise reduction device in which two types of magnetic bodies are arranged alternately, with adjacent cylindrical magnetic bodies connected by elastic members and pins. Patent Document 2 listed below also discloses a noise reduction device in which multiple trapezoidal columnar magnetic bodies are bonded to a film that is then wrapped around an electric wire.

Japanese Patent Application Laid-Open No. 2002-374090 Japanese Patent Application Publication No. 7-297588

However, the noise reduction device in Patent Document 1 has a complex structure due to the large number of components, making it difficult to reduce costs from the perspective of productivity, etc. Furthermore, the noise reduction device in Patent Document 2 uses an adhesive to bond the magnetic material and film, making it difficult to ensure durability from the perspective of heat resistance and changes over time, etc.

The present invention aims to provide a noise reduction device and wire harness that can keep costs low while ensuring durability.

The noise reducer according to the present invention comprises a plurality of columnar magnetic cores extending in the column axis direction, and a sheet-like or strip-like core holding member that holds the plurality of magnetic cores and can be wound around the axis of an electric wire or an electric wire bundle formed by bundling a plurality of electric wires together at least once. The core holding member holds the magnetic cores in a wound shape around the electric wire or the electric wire bundle, arranging each of the magnetic cores at equal intervals one by one for at least one turn around the axis of the electric wire or the electric wire bundle, and has a core holding portion for each magnetic core that holds each magnetic core with the column axis direction aligned with the winding axis direction of the wound shape, and the core holding portion is formed as a fitting portion into which the magnetic core is fitted.

The wire harness according to the present invention comprises an electric wire or an electric wire bundle formed by bundling a plurality of electric wires together, and a noise reducer that reduces external emission of radiated noise from the electric wires or the electric wire bundle. The noise reducer comprises a plurality of columnar magnetic cores extending in the column axis direction, and a sheet-like or strip-like core holding member that holds the plurality of magnetic cores and can be wound around the axis of the electric wires or the electric wire bundle at least once. The core holding member holds the magnetic cores in a wound shape around the electric wires or the electric wire bundle, arranging each of the magnetic cores at equal intervals one by one for at least one turn around the axis of the electric wires or the electric wire bundle, and has a core holding portion for each magnetic core that holds each magnetic core with the column axis direction aligned with the winding axis direction of the wound shape, and the core holding portion is a fitting portion into which the magnetic cores are fitted.

The noise reducer according to the present invention has a simple structure in which its main components are only a magnetic core and a core holding member, and the magnetic core and core holding member are simply fitted together. This makes the noise reducer highly productive and reduces costs. Furthermore, this noise reducer does not use adhesive between the magnetic core and the core holding member, nor does it use adhesive to secure the core holding member to the electric wire WEB or electric wire bundle WEB while maintaining the wound shape of the core holding member. This noise reducer is therefore highly heat-resistant and resistant to changes over time, ensuring high durability. In this way, the noise reducer according to the present invention can keep costs low while ensuring high durability. Furthermore, the wire harness according to the present invention is equipped with this noise reducer and can achieve effects similar to those obtained by this noise reducer.

FIG. 1 is a perspective view schematically showing a wire harness to which a noise reducer according to an embodiment is attached. FIG. 2 is a schematic view of a wire harness to which the noise reducer of the embodiment is attached, viewed in the axial direction. FIG. 3 is a plan view schematically showing the noise reducer before assembly. FIG. 4 is a perspective view showing the magnetic core of the embodiment. FIG. 5 is a schematic view of another use form of the wire harness to which the noise reducer of the embodiment is attached, as viewed in the axial direction. FIG. 6 is a schematic view of a wire harness to which a noise reducer according to the first modification is attached, viewed in the axial direction. FIG. 7 is a perspective view showing a magnetic core according to the first modification. FIG. 8 is a schematic view of a wire harness to which a noise reducer according to the second modification is attached, viewed in the axial direction. FIG. 9 is a perspective view showing a magnetic core according to the second modification.

Embodiments of a noise reducer and a wire harness according to the present invention are described in detail below with reference to the drawings. However, the present invention is not limited to these embodiments.

[Embodiment]
An embodiment of a noise reducer and a wire harness according to the present invention will be described with reference to FIGS. 1 to 5. FIG.

The reference numeral 1 in Figures 1 to 3 indicates a noise reducer according to this embodiment. This noise reducer 1 is attached to an electric wire We through which a noise current flows, thereby reducing the external emission of radiated noise emitted from the electric wire We. Alternatively, this noise reducer 1 is attached to an electric wire bundle Web, which is a bundle of multiple electric wires including an electric wire We through which a noise current flows, thereby reducing the external emission of radiated noise emitted from the electric wire bundle Web (the electric wire We through which a noise current flows among the multiple electric wires). The reference numeral WH in Figures 1 and 2 indicates a wire harness in which the noise reducer 1 is assembled to the electric wire We or the electric wire bundle Web. One or more noise reducers 1 may be provided depending on the length of the electric wire We or the electric wire bundle Web.

This wire harness WH is mounted on an electric vehicle (not shown), such as a BEV (Battery Electric Vehicle) or a PHEV (Plug-in Hybrid Electric Vehicle). As a specific example, this wire harness WH physically and electrically connects the auxiliary secondary battery to the DC/DC converter located between the electric vehicle's drive secondary battery and auxiliary secondary battery. This wire harness WH is responsible for supplying power from the drive secondary battery to the auxiliary secondary battery when charging the auxiliary secondary battery.

This wire harness WH is also used, for example, in a charging system (not shown) for charging the drive secondary battery and auxiliary secondary battery of an electric vehicle.

This charging system is configured for normal or rapid charging, regardless of whether it is for commercial or home use. It comprises an external power source, a charger main unit that receives power from the external power source, and a charging cable with a connector for supplying power from the charger main unit to the vehicle. The charging cable with a connector is used by the operator when supplying power, and comprises a charging cable equipped with at least a power line (electric wire We) and a charging connector attached to one end of the charging cable. Some charging systems control charging by communicating between the vehicle and the charger main unit when supplying power. In this case, the charging cable also comprises a communication signal line for carrying out this communication.

For example, if this charging system is configured for rapid charging, a three-phase AC power supply is used as the external power source, and an AC/DC converter that converts this AC voltage to DC voltage is housed inside the housing of the charger body. In this case, the charging cable with connector supplies the converted power to the vehicle.

The charging cable with connector may be pre-assembled to the charger main unit and may constitute the charger together with the charger main unit. When charging, this charging cable with connector is routed from the charger main unit to the vehicle side, and the charging connector is physically and electrically connected to the electric vehicle's connector (vehicle-side connector).

On the other hand, a charging cable with a connector may be a standalone component that is stored in the trunk of a vehicle, with a power connector attached to the other end of the charging cable. In this case, the charger itself constitutes the charger. When charging, this charging cable with a connector physically and electrically connects the power connector to the connector on the charger itself, and also physically and electrically connects the charging connector to the vehicle connector.

This charging system includes an internal charging cable inside the housing of the charger main body, which electrically connects the AC/DC converter side and the charging cable side. This internal charging cable includes at least an internal power line (electric wire We), which electrically connects the AC/DC converter side and the charging cable side. Therefore, in this charging system, the internal charging cable with the noise reduction device 1 attached becomes the wire harness WH of this embodiment. Note that, if communication is to be performed during charging, the internal charging cable also has an internal communication signal line. Furthermore, in this charging system, the wire harness WH of this embodiment becomes the charging cable of a connector-equipped charging cable with the noise reduction device 1 attached.

The noise reducer 1 and wire harness WH of this embodiment will be described in detail below.

The noise reduction device 1 comprises multiple columnar magnetic cores 11 extending in the column axis direction and a core holding member 21 that holds the multiple magnetic cores 11 (Figures 1 to 3).

The magnetic core 11 is molded from a ferromagnetic material, such as ferrite. The magnetic core 11 shown here is molded into a cylindrical shape (Figures 1 to 4). All of the magnetic cores 11 shown here are molded into the same shape (Figures 1 to 3).

The core holding member 21 is formed in a sheet or band shape that can be wrapped around the electric wire We or electric wire bundle Web at least once around the axis of the electric wire We or electric wire bundle Web (FIGS. 1 to 3). For example, the main body 21a of this core holding member 21 is formed in a flat sheet or band shape before being wrapped around the electric wire We or electric wire bundle Web (FIG. 3), and this flat main body 21a is wound around the electric wire We or electric wire bundle Web (FIGS. 1 and 2). For this reason, the core holding member 21 is formed from a flexible synthetic polymer material (synthetic resin, synthetic rubber, elastomer, etc.).

This core holding member 21 has a main body 21a and a core holding portion 21b for each magnetic core 11 (Figures 1 to 3). Specifically, this core holding member 21 is wound around the electric wire We or electric wire bundle Web in a wound shape, holding each magnetic core 11 at equal intervals around the axis of the electric wire We or electric wire bundle Web for at least one full turn, and has a core holding portion 21b for each magnetic core 11 that holds each magnetic core 11 with the column axis direction aligned with the winding axis direction of the wound shape.

This core holding portion 21b is formed as a fitting portion into which the magnetic core 11 is fitted. The core holding portion 21b shown here is formed as a cylindrical space into which the cylindrical magnetic core 11 can be fitted by press-fitting or the like along the column axis direction.

The core holding member 21 may also be produced, for example, using insert molding technology to place multiple magnetic cores 11 in a mold, so that each magnetic core 11 is fitted into its respective core holding portion 21b.

When this noise reduction device 1 is wound around an electric wire We or an electric wire bundle Web, the smaller the circumferential gap between adjacent magnetic cores 11, the more efficiently it can provide resistance to the magnetic field. This allows for greater reduction in the external emission of radiated noise from the electric wire We or electric wire bundle Web (the electric wire We among multiple electric wires through which a noise current flows). Therefore, this noise reduction device 1 can reduce the circumferential gap between adjacent magnetic cores 11 when wound, for example, by narrowing the gap between adjacent core holding portions 21b of the core holding member 21 in accordance with the desired amount of reduction in radiated noise.

In addition, to further reduce the external emission of radiated noise, the noise reduction device 1 may be wound around the axis of the electric wire We or electric wire bundle Web multiple times, so that the magnetic core 11 is located radially around the entire circumference of the wound device between the axial center of the electric wire We or electric wire bundle Web and the outermost surface of the core holding member 21. Figure 5 schematically shows an example in which the noise reduction device 1 is wound around the electric wire We or electric wire bundle Web one or more times. In this example, the circumferential gap between adjacent magnetic cores 11 may be reduced when the device is wound, or the magnetic core 11 may be located radially between the axial center of the electric wire We or electric wire bundle Web and the outermost surface of the core holding member 21 when the device is wound.

Furthermore, when the noise reduction device 1 is wound around an electric wire We or a bundle of electric wires Web, adjacent magnetic cores 11 come into contact with each other, thereby providing highly efficient resistance to magnetic fields. This effectively reduces the external emission of radiated noise from the electric wire We or the bundle of electric wires Web (those electric wires We through which noise current flows). For example, the core holding member 21 shown here has a communicating portion 21c that connects two adjacent core holding portions 21b and brings the magnetic cores 11 held by these two core holding portions 21b into contact with each other in a wound configuration (Figure 2). This communicating portion 21c is, for example, a portion of the wall between two adjacent core holding portions 21b cut out in the direction of the hole axis (winding axis) of the core holding portions 21b, and is provided for each pair of adjacent core holding portions 21b. When the core holding member 21 is cut, the main body 21a is separated into two sections 21d and 21e, with the communicating section 21c in between. For this reason, a wall section connecting the two sections 21d and 21e is provided at one end of the core holding section 21b in the column axis direction (not shown).

Here, this noise reduction device 1 is equipped with a fixing member 31 that fixes the core holding member 21 to the electric wire We or the electric wire bundle Web while maintaining the wound shape of the core holding member 21 (Figure 2). This fixing member 31 is, for example, a cable tie that is wrapped around the wound core holding member 21, and one or more fixing members 31 are provided depending on the length in the winding axis direction.

As described above, the noise reducer 1 of this embodiment has a simple structure in which its main components are only the magnetic core 11 and the core holding member 21, and the magnetic core 11 and the core holding member 21 are simply fitted together. This makes the noise reducer 1 highly productive and reduces costs. Furthermore, the noise reducer 1 does not use adhesive between the magnetic core 11 and the core holding member 21, nor does it use adhesive to secure the core holding member 21 to the electric wire WEB or electric wire bundle WEB while maintaining the wound shape of the core holding member 21. This makes the noise reducer 1 highly heat-resistant and resistant to changes over time, ensuring high durability. In this way, the noise reducer 1 of this embodiment can keep costs low while ensuring high durability. Therefore, by applying this noise reduction device 1 to the aforementioned electric vehicles and charging systems (whether for normal charging or rapid charging), it is possible to ensure high durability and reduce costs in these electric vehicles and charging systems, thereby contributing to the widespread use of electric vehicles and charging systems. The wire harness WH of this embodiment is equipped with this noise reduction device 1 and can achieve the same effects as those obtained by this noise reduction device 1.

Furthermore, charging systems configured for rapid charging are more likely to generate noise than those configured for normal charging. Therefore, the noise reduction device 1 and wire harness WH of this embodiment are particularly useful in charging systems for rapid charging and electric vehicles that can be rapidly charged using such charging systems.

In the noise reduction device 1 of this embodiment, a sheet-like base material from which multiple core holding members 21 can be cut out may be prepared (not shown). In this case, core holding members 21 of lengths or widths corresponding to the diameter of the electric wires We or electric wire bundles Web can be cut out from the base material, so multiple core holding members 21 of different lengths or widths adapted to electric wires We or electric wire bundles Web of different diameters can be produced from a single base material. Therefore, the noise reduction device 1 and wire harness WH of this embodiment can be said to be even more useful in this respect as it also enables cost reduction.

[Modification 1]
The noise reducer 2 of this modified example is the same as the noise reducer 1 of the above-described embodiment, except that the magnetic core 11 and the core holding member 21 are replaced with a magnetic core 12 and a core holding member 22 (FIG. 6). The noise reducer 2 includes a fixing member 32 similar to the fixing member 31 included in the noise reducer 1 of the embodiment (FIG. 6).

The magnetic core 12 is molded from a ferromagnetic material such as ferrite. The magnetic core 12 of this modified example is molded into a trapezoidal column shape, with a cross section perpendicular to the column axis direction being a trapezoid (Figures 6 and 7). The magnetic core 12 shown here is molded into a trapezoidal column shape, with a cross section perpendicular to the column axis direction being an isosceles trapezoid. All of the magnetic cores 12 are molded into the same shape (Figure 6).

The core holding member 22 is molded from a flexible synthetic polymer material (synthetic resin, synthetic rubber, elastomer, etc.) similar to the core holding member 21 of the previously described embodiment, although the thickness of its main body 22a is different (Figure 6). Like the core holding member 21 of the previously described embodiment, this core holding member 22 has a core holding portion 22b on the main body 22a for each magnetic core 12 (Figure 6). In this modified example, the core holding portion 22b is also formed as a fitting portion into which the magnetic core 12 is fitted.

However, in this modified example, the core holding portion 22b is formed so that the magnetic cores 12 are fitted at their lower bottoms so that the upper bottoms of the magnetic cores 12 are positioned on the wire We side or wire bundle Web side in the radial direction of the wound shape, and the upper bottoms of two adjacent magnetic cores 12 come into contact with each other in the wound shape for each combination (Figure 6). This core holding portion 22b is formed as a trapezoidal columnar space into which the lower bottoms of the magnetic cores 12 can be fitted. For example, the lower bottom side of the magnetic core 12 is fitted into the core holding portion 22b by press-fitting or the like along the columnar axis direction.

The core holding member 22 may also be produced, for example, using insert molding technology to place multiple magnetic cores 12 in a mold, with the lower bottom side of each magnetic core 12 fitted into each core holding portion 22b.

Even though the noise reducer 2 and wire harness WH of this modified example use such a trapezoidal cylindrical magnetic core 12, they can achieve the same effects as the noise reducer 1 and wire harness WH of the previously described embodiment. Therefore, like the noise reducer 1 and wire harness WH of the embodiment, this noise reducer 2 and wire harness WH can be applied to electric vehicles and charging systems, contributing to their widespread use.

Furthermore, charging systems configured for rapid charging are more likely to generate noise than those configured for normal charging. Therefore, the noise reduction device 2 and wire harness WH of this modified example are particularly useful in charging systems for rapid charging and electric vehicles that can be rapidly charged using such charging systems.

[Modification 2]
The noise reducer 3 of this modified example is the same as the noise reducer 1 of the above-described embodiment, except that the magnetic core 11 and the core holding member 21 are replaced with a magnetic core 13 and a core holding member 23 (FIG. 8). The noise reducer 3 includes a fixing member 33 similar to the fixing member 31 included in the noise reducer 1 of the embodiment (FIG. 8).

The magnetic core 13 is molded from a ferromagnetic material such as ferrite. The magnetic core 13 of this modified example is molded into a triangular prism whose cross section perpendicular to the column axis is an equilateral triangle (Figures 8 and 9). All of the magnetic cores 13 are molded to the same shape (Figure 8).

The core holding member 23 is molded from a flexible synthetic polymer material (synthetic resin, synthetic rubber, elastomer, etc.) similar to the core holding member 21 of the previously described embodiment, although the thickness of its main body 23a is different (Figure 8). Like the core holding member 21 of the previously described embodiment, this core holding member 23 has a core holding portion 23b for each magnetic core 13 on the main body 23a (Figure 8). In this modified example, the core holding portion 23b is also formed as a fitting portion into which the magnetic core 13 is fitted.

However, in this modified example, the core holding portion 23b fits the magnetic core 13 at its base so that the apex of the magnetic core 13 is positioned on the wire We side or the wire bundle Web side in the radial direction of the wound shape (Figure 8). This core holding portion 23b is formed as a trapezoidal columnar space into which the bottom side of the magnetic core 13 can be fitted. For example, the bottom side of the magnetic core 13 is fitted into the core holding portion 23b by press-fitting along the columnar axis direction.

The core holding member 23 may also be produced, for example, using insert molding technology to place multiple magnetic cores 13 in a mold, with the bottom side of each magnetic core 13 fitted into its respective core holding portion 23b.

The core holding member 23 of this modified example also has a communicating portion 23c that connects two adjacent core holding portions 23b and allows the bases of the magnetic cores 13 held by these two core holding portions 23b to contact each other in a wound shape (Figure 8). This communicating portion 23c is, for example, a portion of the wall between two adjacent core holding portions 23b cut out in the hole axis direction (winding axis direction) of the core holding portion 23b, and is provided for each pair of adjacent core holding portions 23b. Here, the vertices of the bases of two adjacent magnetic cores 13 are brought into contact with each other via this communicating portion 23c. Furthermore, in this core holding member 23, when the core holding member 23 is cut away, the remaining walls 23d closer to the apex of the magnetic core 13 than the communicating portion 23c are connected together, and a wall portion (not shown) is provided at one end of the core holding portion 23b in the column axis direction that connects these to the bottom side 23e of the magnetic core 13 than the communicating portion 23c.

Even though the noise reduction device 3 of this modified example uses such a triangular prism-shaped magnetic core 13, it can still achieve the same effects as the noise reduction device 1 of the previously described embodiment.

Furthermore, the noise reduction device 3 of this modified example uses a triangular prism-shaped magnetic core 13 whose cross section perpendicular to the column axis direction forms an equilateral triangle, so any of its three sides can be used as the base that fits into the core holding member 23b. This makes it easy to assemble the magnetic core 13 to the core holding member 23, which also contributes to cost reduction.

Furthermore, because the noise reducer 3 of this modified example uses a triangular prism-shaped magnetic core 13, by reducing the cross-sectional area of the magnetic core 13 in a cross section perpendicular to the column axis direction, the number of magnetic cores 13 increases for a given diameter of the electric wire We or electric wire bundle Web, but the sum of the surface areas of the magnetic cores 13 increases. As a result, the noise reducer 3 can improve its heat dissipation performance.

The wire harness WH of this modified example is equipped with this noise reducer 3, and can achieve the same additional effects as this noise reducer 3.

In this way, the noise reducer 3 and wire harness WH of this modified example not only achieve the same effects as the noise reducer 1 of the previously described embodiment, but also achieve additional effects. Therefore, like the noise reducer 1 and wire harness WH of the embodiment, by applying this noise reducer 3 and wire harness WH to electric vehicles and charging systems, they will further contribute to the widespread use of electric vehicles and charging systems.

Furthermore, charging systems configured for rapid charging are more likely to generate noise than those configured for normal charging. Therefore, the noise reduction device 3 and wire harness WH of this modified example are particularly useful in charging systems for rapid charging and electric vehicles that can be rapidly charged using such charging systems.

1, 2, 3 Noise reduction tool 11, 12, 13 Magnetic core 21, 22, 23 Core holding member 21b, 22b, 23b Core holding portion 21c, 23c Communication portion 31, 32, 33 Fixing member We Electric wire Web Wire bundle WH Wire harness

Claims (5)

a plurality of columnar magnetic cores extending in a column axis direction;
a sheet-like or strip-like core holding member that holds a plurality of the magnetic cores and can be wound around an electric wire or an electric wire bundle obtained by bundling a plurality of electric wires at least once around the axis of the electric wire or the electric wire bundle;
a fixing member that fixes the core holding member to the electric wire or the electric wire bundle while maintaining the wound shape of the core holding member wound around the electric wire or the electric wire bundle;
Equipped with
the core holding member holds the magnetic cores in the wound shape, arranged one by one at equal intervals around the axis of the electric wire or the electric wire bundle, for at least one turn, and has a core holding portion for each of the magnetic cores that holds each of the magnetic cores with the column axis direction aligned with the winding axis direction of the wound shape,
The noise reducing tool is characterized in that the core holding portion is formed as a fitting portion into which the magnetic core is fitted. The magnetic core is formed into a cylindrical shape,
the core holding portion is formed as a cylindrical space into which the magnetic core can be fitted along the column axis,
the core holding member has a communicating portion that communicates two adjacent core holding portions and brings the magnetic cores held by the two core holding portions into contact with each other in the wound shape,
The noise reducer according to claim 1 , wherein the communication portion is provided for each pair of adjacent two of the core holding portions. The magnetic core is formed into a trapezoidal columnar shape having a cross section orthogonal to the column axis direction,
2. The noise reducer according to claim 1, wherein the core holding portion is formed in a shape that fits the magnetic core at its lower bottom portion so that the upper bottom portion of the magnetic core is positioned on the electric wire side or the electric wire bundle side in the radial direction of the wound shape, and that brings the upper bottom portions of two adjacent magnetic cores into contact with each other in the wound shape for each combination. The magnetic core is formed into a triangular prism shape having a cross section perpendicular to the column axis direction that is an equilateral triangle,
the core holding portion fits the magnetic core at a bottom side thereof so that a top portion of the magnetic core is disposed on the electric wire side or the electric wire bundle side in a radial direction of the wound shape,
the core holding member has a communicating portion that communicates two adjacent core holding portions and brings the base portions of the magnetic cores held by the two core holding portions into contact with each other in the wound shape,
The noise reducer according to claim 1 , wherein the communication portion is provided for each pair of adjacent two of the core holding portions. an electric wire or an electric wire bundle obtained by bundling a plurality of electric wires together;
a noise reducer that reduces the emission of radiation noise from the electric wire or the electric wire bundle to the outside;
Equipped with
The noise reduction tool is
a plurality of columnar magnetic cores extending in a column axis direction;
a sheet-like or strip-like core holding member that holds a plurality of the magnetic cores and can be wound around the electric wire or the electric wire bundle at least once around the axis of the electric wire or the electric wire bundle;
a fixing member that fixes the core holding member to the electric wire or the electric wire bundle while maintaining the wound shape of the core holding member wound around the electric wire or the electric wire bundle;
Equipped with
the core holding member holds the magnetic cores in the wound shape, arranged one by one at equal intervals around the axis of the electric wire or the electric wire bundle, for at least one turn, and has a core holding portion for each of the magnetic cores that holds each of the magnetic cores with the column axis direction aligned with the winding axis direction of the wound shape,
The wire harness is characterized in that the core holding portion is a fitting portion into which the magnetic core is fitted.