JPH0584046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reactor for large currents, which is formed by surrounding one or more annular magnetic cores with a conductor.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, there is a reactor shown in FIG. 1, for example, as a large current reactor with a relatively small inductance used in power converters and the like using semiconductor elements.

As shown in the figure, this reactor consists of a rod-shaped conductor 1 whose surface is insulated, a plurality of annular magnetic cores 2 that are sequentially sheathed around this conductor 1 and arranged in series in the axial direction, and both ends of the conductor 1. It consists of a terminal 3 attached to the section.

Such a reactor has advantages such as the inductance can be easily adjusted by adjusting the number, shape, size, etc. of the annular magnetic cores, the structure is simple, and the conductor has high mechanical strength against surge currents.

By the way, in such a reactor, conductor 1
In consideration of workability when fitting the annular magnetic core 2 to the annular magnetic core 2, a slight gap is provided between the outer diameter of the conductor 1 and the inner diameter of the annular magnetic core 2. However, this gap weakens the excitation force applied from the conductor 1 to the annular magnetic core 2, resulting in an increase in the required volume of the annular magnetic core to obtain a desired inductance.

Therefore, in order to solve this problem, we divided the annular magnetic core made of electromagnetic steel plate or ferrite into two in the diametrical direction, covered the resulting divided bodies (cut cores) with conductors, and then brought them together again to form a reactor. things are being done. This makes it possible to easily attach the magnetic core to the conductor, and at the same time to improve the adhesion between the conductor and the magnetic core.
However, in order to ensure the above-mentioned adhesion using such a cut core, a special fastening member for fastening the cut core is required, which has the problem of increasing the size of the device.

Further, the bonding condition at the above-mentioned dividing plane was not good, and there was also the problem that the magnetic resistance increased, making it impossible to obtain the desired inductance. Also,
In particular, magnetostriction is noticeable in ferrite, etc., and noise at the split surface sometimes becomes a problem.

[Purpose of the invention]

The present invention has been made in view of the above, and an object of the present invention is to form a conductor, a magnetic core, and the divided bodies without particularly requiring a fastening member, even though the annular magnetic core is composed of a plurality of divided bodies. It is an object of the present invention to provide a reactor which can ensure high adhesion between the divided bodies and the reactor, which can have a smaller external size and a simpler structure.

[Summary of the invention]

In the reactor according to the present invention, the annular magnetic core is
It is composed of a set of divided bodies divided into a plurality of parts in the circumferential direction, and each divided body is integrally connected by the fitting connection of grooves and protrusions formed in the divided bodies. . 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 a plurality of divided bodies, the exterior work of the magnetic core to the conductor can be performed extremely smoothly.

These divided bodies can increase the degree of adhesion between the joints of each other due to the wedge action between the protrusions and grooves formed on the divided bodies, thereby strengthening the magnetic coupling between the divided bodies. At the same time, it is possible to improve the adhesion between the conductor and the divided body.
As a result, the required magnetic core volume to obtain the desired inductance can be set small. Moreover, since the divided bodies can be connected to each other without using a fastening member, there is a great effect that the overall size can be reduced and the structure can be simplified.

[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 reactor according to an embodiment of the present invention.

The reactor according to this embodiment includes a rod-shaped conductor 1 whose surface is covered with an insulating layer, and a plurality of annular magnetic cores 4 which are sequentially sheathed around the conductor 1 and arranged in series in the axial direction.
and terminals 3 attached to both ends of the conductor 1. The annular magnetic core 4 is formed by fitting and connecting the divided bodies 5 and 6.
For example, a mixture obtained by mixing Fe-1.5% Si alloy magnetic powder with an average particle size of 53 μm and semi-hardened epoxy resin powder at a volume ratio of 85:15 is molded.
It is formed by compression molding at a pressure of 600MPa.
The divided body 5 is provided with grooves 9 and 10 extending in the axial direction on both end surfaces 7 and 8, respectively, as shown in FIG. Projections 1 extending in the axial direction at 11 and 12
3 and 14 are provided. The grooves 9 and 10 are each formed in the same shape, the width of which gradually narrows 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 protrusions 13 and 14 have a shape corresponding to the grooves 9 and 10, that is, a shape whose overall width gradually becomes narrower as it advances in the axial direction, and whose width is smaller at the base end than at the tip end. It is formed into a narrower shape.

Then, the pair of divided bodies 5 and 6 are attached to the conductor 1, and the groove 9 and the protrusion 14 are fitted together, and the groove 10 and the protrusion 13 are fitted together as shown in FIG. By sliding the divided bodies 5 and 6 relatively in the axial direction in this state, the divided bodies 5 and 6 are connected to assemble one annular magnetic core 4 , and the desired number of annular magnetic cores 4 is assembled by following the same procedure. After attaching to the outer circumference of conductor 1,
For example, a reactor is formed by applying heat treatment at 150°C for 15 minutes to integrate the joint surfaces.

With such a configuration, the annular magnetic core 4 can be attached to the conductor 1 very easily since it is only necessary to attach the divided bodies 5 and 6 to the conductor 1 and fit the grooves and the protrusions. Furthermore, when the divided bodies 5 and 6 are joined together, if the divided bodies 5 and 6 are slid relative to each other in the direction of the dotted line arrow in FIG. The protrusion 13 formed in
As a result, the side walls 24, 25 and the side walls 26, 27 form an angle with respect to the axial direction, so that 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 joint surfaces of the divided bodies 5, 6 and the joint surfaces of the divided bodies 5, 6 and the conductor 1 are strongly brought into close contact, and the divided bodies are bonded to 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 effects can be obtained.

In addition, since it is possible to maintain high adhesion between the conductor 1 and the annular magnetic core 4 , for example, in a reactor in which a copper pipe is used for the conductor 1 and cooling water is circulated inside the conductor, the cooling efficiency is improved. It also leads to increasing.

Further, since the divided bodies 5 and 6 in this embodiment have a shape that can be molded with a 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. is formed, and a protrusion 3 is formed on the other end surface.
2 may be formed. 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. In other words, the mechanical bonding strength between the divided bodies can be ensured, and the wedge effect that accompanies the sliding of both divided bodies in the axial direction can increase the degree of adhesion between the joints between the two bodies and the degree of closeness to the outer circumferential surface of the conductor. Any shape is fine. Alternatively, the annular magnetic core may be constructed of three or more divided bodies. Furthermore, the material of the dividing body is not limited to those specifically described in the above embodiments.
It may also be ferrite or the like. When using powder magnetic material, for example, iron powder, Fe-Si alloy powder, Fe
- Soft magnetic powders such as Ni alloy powder, Fe-Si-Al alloy powder, Fe-Co alloy powder, Ni powder, Fe-Al alloy powder, etc., and thermoplastic resins such as polyamide resin, polyester resin, polycarbonate resin, etc. It is best to use a mixture of thermosetting resin in a hardened state, such as a mixture obtained by mixing Fe-Ni alloy powder with an average particle size of 44 μm and polyamide resin at a volume ratio of 8:2. may be molded under a pressure of 500 MPa. In this way, if the average particle size of the magnetic powder is 100 μm or less, the high frequency characteristics and surface roughness after molding will be good, and if the average particle size of the magnetic powder is 10 μm or more, there will be no problems in handling the metal powder. It will not be a hindrance. In addition, if the amount of resin in the powder magnetic material is 1.5% or more by volume, the strength of the magnetic core and the mutual insulation of the magnetic powder will be good.
A reactor that fully exhibits the effects of the present invention can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the external appearance of a conventional reactor, Fig. 2 is a perspective view showing the external appearance of a reactor according to an embodiment of the present invention, and Fig. 3 a and b are divisions forming the annular magnetic core of the reactor. A perspective view showing the body;
FIG. 4 is a perspective view showing the divided body in the middle of being fitted, and FIGS. 5 and 6 are perspective views showing the divided body constituting a reactor according to another embodiment of the present invention. 1... Conductor, 2, 4 ... Annular magnetic core, 3... Terminal, 5,
6, 30, 33...divided body, 9, 10, 31, 34
... Groove, 13, 14, 32, 35... Projection.

Claims (1)

[Claims] 1. A reactor comprising one or more annular magnetic cores attached to the outer periphery of a rod-shaped conductor, wherein the annular magnetic core is composed of a plurality of divided bodies connected in series in an annular shape to form a closed magnetic path. , the joint end surfaces of these divided bodies that are joined to each other are fitted into each other by relative sliding in the axial direction of the adjacent divided bodies, mechanically connecting the adjacent divided bodies to each other, and A reactor characterized in that a joint between adjacent divided bodies is formed with protrusions and grooves having wall surfaces inclined in the axial direction to increase the degree of adhesion between the mutually joined parts as the sliding occurs. 2. Claim 1, characterized in that the divided body is obtained by compression molding a mixture of soft magnetic metal powder and thermoplastic or semi-hardened thermosetting resin. Reactor listed.