JPS6050909A - Choke coil - Google Patents

Abstract

PURPOSE:To reduce the magnetic resistance of the junction part without the need of tightening members by a method wherein an annular magnetic core is composed of the assemblage of split bodies, which are then coupled into an integral body by the fit-coupling of grooves formed in the split body with projections thereof. CONSTITUTION:The choke coil consists of the annular magnetic core 3 and a coil 4 wound around this core. The core 3 is formed by the fit-coupling of the split bodies 5 and 6. The split body 5 is provided with the grooves 9 and 10 extending in the axial direction at both end surfaces 7 and 8, respectively. On the other hand, the split body 6 is provided with the projections 13 and 14 extending in the axial direction at both end surfaces 11 and 12. In such a construction, the split bodies 5 and 6 can be coupled only by fitting the grooves with the projections after winding each to the bodies 5 and 6, therefore the work of winding becomes easy, and the work of winding by means of machines can be also employed. Besides, since the junction area of the bodies 5 and 6 is made larger than that of the abutment of planes against each other, the magnetic resistance in the junction part can be kept low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a choke coil formed by winding a coil around an annular magnetic core.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, various types of filters have been used at signal input/output portions in electronic devices such as various communication devices, information devices, and power supply circuits. In particular, in such a filter,
As schematically shown in FIG. 1, a choke coil constituting a high-frequency filter is composed of an annular magnetic core 1 made of a so-called dust core, a ferrite core, etc., and a coil 2 wound around the annular magnetic core 1.

However, although the choke coil configured as described above has the great advantage of having little magnetic flux leaking from the magnetic core to the outside, the winding process around the annular magnetic core is very complicated, especially when the coil is wound around a small annular magnetic core. When used, there was a problem that mechanical winding was not possible.

Therefore, in order to solve this problem, a choke coil is constructed using a so-called cut core, in which the annular magnetic core is divided into two parts, each of which is wound beforehand, and then butted together again at the divided surfaces. It is also being done,
When using a cut core, a special fastening member is required to fasten the cut core. Therefore, there is a problem in that the element becomes large in size, and it is not possible to wind a portion of the annular magnetic core occupied by the fastening member, resulting in a decrease in the space factor of the magnetic core.

Furthermore, since the joint area of each divided body on the dividing plane is the same as the cross-sectional area of the magnetic path, there is also a problem in that the magnetic resistance corresponding to the air gap increases.

[Purpose of the invention]

The present invention has been made in view of the above, and an object of the present invention is to construct an annular magnetic core with a plurality of divided bodies, but to separate the divided bodies without particularly requiring a fastening member. It is an object of the present invention to provide a choke coil which can be easily wound and miniaturized by reducing the magnetic resistance of the joint portion of the choke coil.

[Summary of the invention]

In the choke coil C according to the present invention, the coil-shaped magnetic core is constituted by a set of divided bodies divided into a plurality of parts in the circumferential direction, and each part is formed by fitting and connecting grooves and protrusions formed in the divided bodies. The divided bodies are integrally connected. The grooves and the protrusions are provided so as to exhibit a wedge effect that increases the degree of adhesion between the joined portions of the divided bodies by relative sliding of the divided bodies in the axial direction.

〔Effect of the invention〕

According to the present invention, since the annular magnetic core is composed of the same number of divided bodies as the columns, winding can be applied to the divided bodies in advance, and the winding process can be extremely simplified.

These split bodies can increase the degree of adhesion of the mutually joined parts by the wedge action of the protrusions and grooves formed on the divided bodies, and the joint surface area is larger than that of the cut core type strain joint. Therefore, it is possible to reduce the magnetic resistance between the divided bodies, that is, to strengthen the magnetic coupling. Moreover, since the divided bodies can be connected to each other without using a fastening member, the space factor of the magnetic core relative to the coil can be improved, and as a result, the choke coil can be made smaller, resulting in great effects.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained based on illustrated embodiments.

FIG. 2 is a perspective view showing the appearance of a choke coil according to an embodiment of the present invention.

The choke coil according to this embodiment is composed of an annular magnetic core and a coil 4 wound around the annular magnetic core. The annular magnetic core l is formed by fitting and connecting the divided bodies 5 and 6, and the divided body 5°6 is made of, for example, 5377 m of Fe.
-1.5% S1 alloy magnetic powder and semi-hardened epoxy resin powder are mixed at a volume ratio of 85:15, and the resulting mixture is compression-molded in a mold at a pressure of 600 MPa. There is. The divided body 5 is provided with grooves 9 and 1o extending in the axial direction on both end surfaces 7 and 8, respectively, as shown in FIG. As shown in the figure, axially extending protrusions 13.14 are provided on both end faces 11.12. The grooves 9 and 10 are each formed in the same shape, and the width thereof gradually becomes narrower as it advances in the axial direction, and the width of the bottom surface is wider than the width of the opening surface. is formed. The protrusion 13.74 has a shape corresponding to the grooves 9 and 1o, the width of the tab gradually narrows as it advances in the axial direction, and the width of the proximal end is larger than the width of the tip. It is formed into a narrow shape.

After winding tm on each of the divided bodies 5 and 6, the groove 9 and the protrusion 14 are fitted together, and the groove 1o and the protrusion 13 are fitted together as shown in FIG. The divided bodies 5 and 6 are connected by sliding the bodies 5 and 6 relative to each other in the axial direction, and in this state, heat treatment is performed at 150°C for 15 minutes to integrate the joint surfaces and connect the annular magnetic cores. After that, the coil 4 is formed by connecting the windings wound around each of the divided bodies 5 and 6.

With this configuration, the winding work is easy because after winding each of the divided bodies 5 and 6, the grooves and the protrusions are fitted together to connect the divided bodies 5 and 6. Mechanical winding work can also be used. Furthermore, when the divided bodies 5 and 6 are combined, if they are slid relative to each other in the direction of the dotted line arrow in FIG.
and the side walls 26.27 of the protrusions 14 formed on the divided body 6 slide, and as a result, the side walls 24.25 and the side walls 2
6.27, the divided bodies 5.6 move in a direction in which they come into close contact with each other, as shown by the solid line arrows in the figure. Therefore, the divided bodies are bonded to each other in such a way that the bonding surfaces are in close contact with each other.

In addition, since the joint area between the dividing body 5 and the dividing body 6 is expanded by approximately the side wall of the protrusion, compared to simply abutting planes, the magnetic resistance at the joint can be kept low. As a result, the above-mentioned effect can be obtained.

In addition, experiments conducted by the present inventors have confirmed that the choke coil of this example has no difference in inductance value compared to a monolithic choke coil having the same shape and composition.

Further, since the divided bodies 5 and 6 in this embodiment have a shape that can be molded with a metal mold, productivity is also good.

In this embodiment, only grooves were formed in one of the divided bodies 5 and only protrusions were formed in the other divided body 6, but for example, as shown in FIG. 3, and a protrusion 32 may be formed on the other end surface.

If the divided body has such a shape, only one type of mold is required, which is more economical.

Further, the annular magnetic core is not limited to a circular shape, but may be composed of rectangular divided bodies 33, as shown in FIG. 6, for example.

Furthermore, the shapes of the grooves and protrusions of the divided body are not limited to those described above. Any shape may be used as long as it can ensure the mechanical bonding strength between the pick and the divided bodies, and can increase the degree of adhesion between the joints of the two divided bodies by the wedge action that occurs when the two divided bodies slide in the axial direction. Further, the annular magnetic core may be constructed of three or more divided bodies. Furthermore, the material of the divided body is not limited to those specifically described in the above embodiments, and may be ferrite or the like. When using powder magnetic material, for example, iron powder, Fe −
Si alloy powder.

p's -Ni alloy powder, Fe-8i-At alloy powder, F
e-C.

Soft magnetic powder such as alloy powder, Nl powder, Fe-At alloy powder, polyamide resin, polyester resin.

It is preferable to use a mixture of thermoplastic resin such as polycarbonate resin or semi-cured thermosetting resin, for example, Fe-Ni alloy powder with an average particle size of 44 μm and polyamide resin in a volume ratio of 8: The mixture obtained by mixing in step 2 may be molded at a pressure of 500 MPa. As described above, if the average particle size of the magnetic powder is 100 μm or less, the high frequency characteristics and the surface roughness after molding will be good. In addition, the amount of resin in the dust magnetic material is 1 in volume ratio.
．． If it is 5 or more, the strength of the magnetic core and the mutual insulation between the magnetic powders will be good, and a choke coil that fully exhibits the effects of the present invention will be obtained.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the appearance of a conventional choke coil, Fig. 2 is a perspective view showing the appearance of a choke coil according to an embodiment of the present invention, and Figs. 3(a) and (b) are the same choke coil. 4th perspective view showing the divided bodies constituting the annular magnetic core of
This figure is a perspective view showing a state in which the divided bodies are being fitted together, and FIGS. 5 and 6 are perspective views showing divided bodies constituting choke coils according to other embodiments of the present invention. 1.3...Annular magnetic core, 2.4...Coil, 5,6°30.33...Divided body, 9,10,31.34...
Mizo, 13, 14, 32.35...Toto. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Sukui Figure 3 Figure 4 Figure 5 Figure 6 Figure 34 35

Claims (2)

[Claims] (1) In a choke coil formed by winding a coil around a ring-shaped magnetic core, both end surfaces of the ring-shaped magnetic core are used as joint surfaces for magnetically connecting them in series, and in each series connection, one A plurality of divided bodies forming an annular magnetic path, and a relative relationship in the axial direction of the adjacent divided bodies provided in a pairwise relationship with each other on the end face portions of the divided bodies adjacent in the circumferential direction of these divided bodies. ridges and grooves extending in the axial direction that are fitted into each other by a slide to form a mechanical connection between the adjacent divided bodies and to increase the degree of adhesion of the mutually joined portions by a wedge action accompanying the slide; A choke coil comprising: (2) The divided body is obtained by compression molding a mixture of soft magnetic metal powder and thermoplastic or semi-hardened thermosetting resin. The choke coil described in item 1.