JP3205356B2 - Coil device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to various transformers,
The present invention relates to a coil device that is applied to a choke coil or the like and that forms a magnetic circuit by combining a U-shaped core and an I-shaped core.

[0002]

2. Description of the Related Art A coil device of this type includes an E device shown in FIG.
I type coil device 10, EE type coil device 20 shown in FIG.
Etc. are mainly used. These coil devices 1
Nos. 0 and 20 have a configuration in which gaps 11 and 21 are provided in the magnetic circuit in order to increase the inductance accuracy.

The EI type coil device 10 forms a magnetic circuit by combining an E-shaped core 12 and an I-shaped core 13 by providing a gap 11, and a central leg 12 a of the E-shaped core 12.
And a coil 14 wound therearound. However, since the gap 11 is provided outside the coil 14, heat generated by the eddy current of the coil 14 is small, but the leakage magnetic flux 15 to the outside is large, which adversely affects other components and peripheral devices. The gap 11 is formed mainly by sandwiching the film sheet between the E-shaped core 12 and the I-shaped core 13. For this reason, automatic assembly is difficult, and in order to change the size of the gap 11, a film sheet of that type is required.

[0004] The EE type coil device 20 includes a central leg 22.
The E-shaped core 22 and the E-shaped core 23 are provided with a gap 21 between a and 23a to abut a leg end face of each other to form a magnetic circuit, and a coil 2 is attached to central leg portions 22a and 23a.
4 is wound. In this case, when the magnetic flux leaking from the gap 21 links the coil 24,
Since an eddy current is generated in the fin and is consumed as heat, there is little leakage magnetic flux to the outside. However, there is a disadvantage that the heat generated by the coil 24 near the gap 21 increases. Although the accuracy of the inductance depends on the accuracy of the gap 21, the gap 21 is provided only at the center legs 22a and 23a.
Is large, and the variation is large.

In order to alleviate these problems, a UI coil device 30 shown in FIG. 4 has begun to be used as a coil device for such a transformer and choke coil. The UI-type coil device 30 shown in FIG. 1 includes a U-shaped core 32, an I-shaped core 33, an I-shaped coil unit 37 including a resin bobbin 36 and a coil 34 holding the I-shaped core 33. A magnetic circuit is formed by arranging an I-shaped core 33 between the two leg portions 32a and 32b of the U-shaped core 32 such that a gap 31 is formed on one or both end faces.
The coil 34 is wound around the bobbin 36 holding . The gap 31 is often provided on both end faces of the I-shaped core 33. In addition, this gap 31 is
The gap size can be adjusted by managing the dimensional difference ΔL between the distance Lu between the inner surfaces 32 c and 32 d of the a and 32 b and the length Li in the longitudinal direction of the I-shaped core 33.

The UI type coil device 30 is, for example, an EI
It has been confirmed that the leakage magnetic flux 35 is reduced as compared with the die coil device 10. Further, since the UI coil device 30 has two gaps 31 and has a smaller gap size per location than the EE type coil device 20 having only one gap 21, it has an external Since a small amount of magnetic flux leaks to the coil 34 and a part of the gap 31 goes out of the coil 34 due to the structure of the coil 34, the coil 3
There is a merit that less heat is generated in 4. Further, by changing the length of the I-shaped core 33, the size of the gap 31 can be easily changed. A coil 34 is wound around the bobbin 36, and a hollow portion 36a of the bobbin 36 is formed.
The I-shaped core 33 is inserted into the inside, and the insertion-side tip 36a of the bobbin 36 is U-shaped between the legs 32a of the U-shaped core 32.
Since it is manufactured by a method of inserting until it comes into contact with the character-shaped core 32, it has an advantage that it can also cope with automatic assembly. Therefore, the UI coil device 30 is increasingly used.

[0007]

However, this U
As shown in FIG. 4, when forming the U-shaped core 32, the I-type coil device 30 polishes a fired body made of ferrite powder or the like on the inner surfaces 32c, 32d of the legs 32a, 32b to obtain a dimension Lu. Like that. The dimensional difference ΔL is small,
Since the corners of the inner surfaces 32c, 32d of the legs 32a, 32b are edges, when the relative positions of the bobbin 36 and the U-shaped core 32 are shifted as shown in FIG.
There is a problem that the insertion-side tip 36a of the bobbin 36 hits the legs 32a and 32b, and the bobbin 36 cannot be inserted properly.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coil device which has a small leakage magnetic flux and is easy to assemble.

[0009]

According to the present invention, there is provided a coil device comprising a U-shaped core and an I-shaped core to form a magnetic circuit, wherein the U-shaped core has two legs. In a coil device provided with a bobbin holding an I-shaped core so that the I-shaped core is disposed with a gap at both ends inside a front end surface, the bobbin has one end face of one of the two leg portions. The other end surface is inserted between the two leg portions so as to form a gap between the other leg portion and the other inner surface of the both leg portions.
A gap formed at one end of the I-shaped core is communicated to the outside by providing an inclined surface on the inner surface of the distal end of the leg that contacts one end surface of the bobbin among the two legs of the I-shaped core. It is intended to be.

[0010]

According to the coil device of the present invention constructed as described above, the inclined surface provided on the inner surface of the tip of the leg of the U-shaped core is used.
The bobbin holding the I-shaped core can be easily inserted. Ma
In addition, the I-shaped core has not only a gap at one end but also the other end.
Side gap also communicated to the outside by the formation of the inclined surface
It becomes a gap, so through an inclusion (for example, a bobbin)
Since the heat dissipation effect is large compared to the formed gap,
Heat generation at the coil winding portion can be suppressed. In addition,
Magnetic flux passing through the I-shaped core due to the inclined surface provided on the inner surface of the tip
Leakage to the outside is reduced.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a coil device 40 according to an embodiment of the present invention.
FIG. The present coil device 40 includes, for example, a U-shaped core 42 made of ferrite, an I-shaped core 43 made of ferrite, for example, configured similarly to the conventional coil device 30 shown in FIG. 4, a bobbin 46 made of resin holding the core 43, and And an I-shaped coil portion 47 composed of a coil 44.

The U-shaped core 42 has, for example, a C0.5 chamfer (inclined surface) 4 at the tip of the inner surface 42d of the lower leg 42a.
2 g. The other corners of the U-shaped core 42 are provided with C0.4. With this chamfer 42g,
When the I-shaped coil portion 47 is inserted between the two leg portions 42a and 42b of the U-shaped core 42, the insertion-side tip 46a of the bobbin 46 is inserted.
Are prevented from being caught on both legs 42a and 42b of the U-shaped core 42. Therefore, the chamfer 42g may be formed at the tips of the inner surfaces 42c, 42d of the two legs 42a, 42b, respectively, or may be formed in an arc shape.

The above-described coil device 40 constructed as described above
One manufacturing method will be described.

First, a magnetic powder such as a ferrite powder is fired to obtain a fired U-shaped core. Next, after the inner surfaces 42c and 42d of the two leg portions 42a and 42b are polished flat by a polishing tool, a chamfer 42g is formed on the tip of the inner surface 42d of the lower leg portion 42b by the same polishing tool. The letter core 42 is obtained. Note that the chamfer 42g may be formed before finishing the inner surfaces 42c and 42d, or may be formed simultaneously. Further, the chamfer 42g may be formed at the time of firing the powder.

After the U-shaped core 42 shown in FIG. 1 is obtained, the I-shaped coil portion 47 is set using the lower inner surface 42d as a reference surface.
The bottom surface of the bobbin 46 is brought into contact, and the I-shaped coil portion 47 is inserted between the two leg portions 42a and 42b. I-shaped coil part 47
As shown in FIG. 1, the two legs 42a, 4
Inserted between 2b. The I-shaped core 43 includes two legs 42.
a, 42b are disposed inside the respective distal end faces,
Desired gaps 41 are formed at the ends of the a and b and both end faces of the I-shaped core 43. Also, the bottom surface of the bobbin 46 contacts the inner surface of the one leg, but the upper end surface of the bobbin 46 does not contact the inner surface of the other leg, so that a gap is formed. The upper gap communicates with the outside, and the gap below the I-shaped core 43 also communicates with the outside via the inclined surface 42g.

According to the above-described embodiment apparatus 40,
Since the I-shaped core portion 47 can be easily inserted between the two leg portions 42a and 42b of the U-shaped core 42 in parallel without being surely inclined, it is easy to assemble, and a desired gap is provided at both end surfaces of the I-shaped core 43. Since 41 can be formed, the accuracy of the inductance is improved, and the leakage magnetic flux can be reduced as compared with, for example, the EI coil device. Further, compared with, for example, an EE-type coil device, a part of the gap 41 in the structure of the coil 44 goes out of the coil 44, so that the coil 44 does not generate heat much. In addition, since the gap is formed without using a conventionally used film sheet, automatic assembly becomes possible. Further, by changing the length of the I-shaped core 43, the size of the gap 41 can be easily changed. Further, when compared with the conventional UI coil device shown in FIG. 4, the inclined surface provided on the tip side of the U-shaped core reduces the leakage of magnetic flux passing between the I-shaped core to the outside, so that the leakage is reduced. Magnetic flux is further reduced. Also, I
The gaps formed at both ends of the U-shaped core are both inclusions
Because it is a gap that communicates with the outside without going through
Improves heat dissipation effect and suppresses heat generation in coil windings
it can.

The present invention is not limited to the above embodiment,
Various modifications can be made without departing from the scope of the invention.

[0019]

According to the present invention described in detail above, the U-shaped
The I-shaped core is formed by the inclined surface provided on the inner surface of the leg tip
The held bobbin can be easily inserted. Also, I-shaped core
Not only the gap at one end but also the gap at the other end
The formation of the inclined surface results in a gap communicating with the outside.
Therefore, the gear formed through the inclusion (for example, bobbin)
The heat dissipation effect is greater than that of the
Heat generation can be suppressed. Also, it is installed on the inner surface of the tip.
Leakage of magnetic flux through the I-shaped core due to the inclined plane
Is reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a coil device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional EI coil device.

FIG. 3 is a sectional view of a conventional EE-type coil device.

FIG. 4 is a sectional view of a conventional UI coil device.

FIG. 5 is a cross-sectional view showing a problem during a conventional assembling of the UI coil device shown in FIG.

[Explanation of symbols]

 Reference Signs List 40 Coil device 41 Gap 42 U-shaped core 42 a, 42 b Leg 42 c, 42 d Leg inner surface (polishing surface) 42 g Chamfer 43 I-shaped core 44 Coil 46 Bobbin 47 I-shaped coil

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Kinoshita, inc. 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (56) References JP-A-62-259409 (JP, A) −49955 (JP, U)

Claims (2)

(57) [Claims] 1. A coil device in which a U-shaped core and an I-shaped core are combined to form a magnetic circuit, wherein the I-shaped core is provided with gaps at both ends inside a space between tip surfaces of both legs of the U-shaped core. In a coil device provided with a bobbin holding an I-shaped core so that the bobbin is disposed so that the bobbin has one end surface in contact with one inner surface of the two leg portions, and the other end surface has the other inner surface of the two leg portions. And a gap is formed between the two legs so as to be inserted between the two legs. Of the two legs of the U-shaped core, the inner surface at the tip end of the leg in contact with the one end surface of the bobbin is provided. A coil device wherein an inclined surface is provided so that a gap formed at one end of the I-shaped core communicates with the outside. 2. The coil device according to claim 1, wherein the inclined surface is a chamfer of C 0.2 mm or more or an arc of R 0.2 mm or more.