JP2714997B2 - Coil device - Google Patents

Description

The present invention relates to an improvement in a coil device used for a flyback transformer, a transformer for a switching power supply, a choke coil, and the like, and particularly to the use of a magnetic core having a gap. It relates to improvement of a coil device.

(Prior Art) Conventionally, in a transformer, a choke coil, and the like, a gap is provided in a magnetic path so that a magnetic core does not saturate when a target current flows. For example, the magnetic permeability μ of a ferrite core is
Although it is about 5000, when it is used as a transformer core, a gap is provided to use an effective magnetic permeability μ of 50 to 300.

This means that a gap having a large reluctance must be inserted in a ferrite core having a small reluctance, and a large leakage magnetic flux is generated around the gap.

It is known that this leakage magnetic flux has at least two adverse effects as described below.

Generation of noise on peripheral devices (parts) that are easily affected by magnetic induction.

When the coil is wound so as to surround the gap, the coil around the gap generates abnormal heat due to the leakage magnetic flux.

Therefore, various improvements have been studied for these problems.

For example, in order to solve the above-mentioned problem, a method of providing a gap only in the coil is known, but this method alone further increases the above-mentioned problem.

Regarding the above, JP-A-55-77115, 57-1
As disclosed in Japanese Patent No. 30402, there is also an example in which a gap located in a coil is magnetically divided in series and into a plurality to disperse the concentration of leakage magnetic flux.
Japanese Utility Model Publication No. 53-53850 and Japanese Utility Model Publication No. 60-7448 disclose the above-mentioned problems. These materials have a relative permeability higher than that of air (1 or more) as a gap filling material. To reduce the magnetic reluctance to reduce the leakage magnetic flux.

(Problems to be Solved by the Invention) When a material (1 or more) having a relative magnetic permeability larger than that of air is provided as a gap inside the coil as described above,
There is a possibility that both problems can be improved to some extent.

 However, even in such a case, leakage magnetic flux concentrates at the boundary between the gap and the magnetic core.

II. It is difficult to obtain a magnetic material that has an appropriate magnetic permeability as a gap material, and has a high saturation magnetic flux density comparable to that of a magnetic core and low core loss characteristics.

For example, the coil on the boundary between the gap and the magnetic core abnormally generates heat, the gap generates abnormal heat due to the loss of the magnetic core of the gap material, and the BH curve of the magnetic core with a gap becomes non-linear and used as a transformer. In this case, a new problem that the waveform is distorted occurs, and no more effective improvement plan has been obtained at present.

In the above-mentioned conventional improvement plans, large leakage magnetic flux is generated around the gap despite the complicated structure such as providing a gap of another gap material instead of an air gap, or dividing into multiple parts. Since the occurrence of the problem cannot be sufficiently reduced, problems such as an increase in cost and a decrease in reliability occur.

The present invention solves the above problems, has high saturation resistance to magnetic flux, reduces the influence of noise on peripheral devices (parts), reduces the leakage magnetic flux generated around the gap, and reduces the coil around the gap. It is an object of the present invention to provide a coil device that can prevent occurrence of abnormal heat generation, is inexpensive, and has improved reliability.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a magnetic path,
In a coil device comprising a magnetic core having a non-contact gap in a magnetic core portion in the magnetic path, and coils wound respectively so as to include a region forming the gap of the magnetic core, one or more coils are provided in the gap. A shape in which two or more magnetic core members are arranged to form a plurality of gaps, and at least one of magnetic core portions located at both ends of a region where the plurality of gaps are formed is tapered from the base end toward the center of the tip end. The cross-sectional area of the distal end portion is smaller than the cross-sectional area of the proximal end portion, and the lateral cross-sectional area of the magnetic core member disposed in the gap is changed to the distal end portion of the core of the gap forming portion. Is smaller than the cross-sectional area in the lateral direction.

Further, a coil device having a plurality of gaps having the above configuration may be used.

(Operation) By dividing the inside of the gap around which the coil is wound into a plurality of gaps, the concentration of the leakage magnetic flux can be dispersed over the entire length of the coil. Since the taper shape is tapered from the end to the center of the tip, the magnetic flux is concentrated at the center of the tip to reduce the leakage magnetic flux, and the core member disposed inside the gap has a size within the tip area of the core. So
Since the leakage magnetic flux flowing outward from the insertion core member can also be reduced, abnormal heat generation inside the coil can be completely prevented.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 (a) and 1 (b) are a schematic view and a plan view showing a first embodiment of a coil device according to the present invention. In the coil device 1, a magnetic core portion is opposed to each other via a non-contact gap 5. FIG. It comprises an O-shaped magnetic core 2 having one leg 2 a and a second leg 2 b, a core member 3 disposed in a gap 5, and a coil 6. The gap 5 is divided by the core member 3 into a first gap 5a and a second gap 5b. A coil 6 is wound so as to cover these gaps 5a and 5b. A flat core member 4 is provided at the tip of each of the opposing first and second legs 2a and 2b. As the O-shaped magnetic core 2 and the core member 4, for example, ferrite is used. In the coil device 1 having such a structure,
Each of the opposed first and second legs 2a, 2b
Lateral cross-sectional area B at the distal end rather than lateral cross-sectional area A at the base end
Is formed in such a shape as to be smaller.

2 (a) and 2 (b) are a schematic view and a plan view showing a second embodiment of the present invention, in which a coil device 1 has a first leg 2a and a first leg 2a facing each other with a gap 5 therebetween. An O-shaped magnetic core 8 having two legs 2b, and a first core 8 disposed in the gap 5;
Core member 3a, second core member 3b and third core member 3c
And a coil 6. The gap 5 is formed by the first to third core members 3a, 3b, 3c.
a, a second gap 5b, a third gap 5c, and a fourth gap 5d. A coil 6 is wound so as to cover these gaps 5a to 5d. A flat core member 4 is provided at the tip of each of the opposing first and second legs 2a and 2b. Further, similarly to the first embodiment, each of the opposing first and second legs 2a and 2b has a lateral cross-sectional area B at the distal end portion larger than a lateral cross-sectional area A at the base end portion. It is formed in a smaller shape.

3 (a) and 3 (b) are a schematic view and a plan view showing a third embodiment of the present invention. The coil device 1 has a first section U having first and second legs 9a and 9b. A second U-shaped core 10 having a U-shaped core 9 and first and second legs 10a, 10b;
In the gap 5 between each first leg 9a, 10a and each second leg
It comprises a core member 3 arranged in a gap 5 between 9a and 10b, a first coil 6 and a second coil 7. The gap 5 is divided by the core member 3 into first and second gaps 5a and 5b. First and second sections U
The magnetic cores 9 and 10 are arranged such that the first legs 9a and 10a and the second legs 9b and 10b face each other with gaps 5a and 5b interposed therebetween. The first and second coils 6, 7 are wound so as to cover the first and second coils. A flat core member 4 is provided at the tip of each leg.
Further, each of the first leg portions 9a and 10a and the second leg portions 9b and 10b is formed in a shape in which the lateral cross-sectional area B at the distal end is smaller than the lateral cross-sectional area A at the base end. .

FIGS. 4 (a) and 4 (b) are a schematic view and a plan view showing a fourth embodiment of the present invention. The coil device 1 has a first section U having first and second legs 11a and 11b. -Shaped core 11 and a second U-shaped core 12 having first and second legs 12a, 12b.
And the first, second and third core members disposed in the gap 5 between the first legs 11a and 12a and between the second legs 11b and 12b.
3a, 3b, and 3c, and first and second coils 6 and 7. The gap 5 is divided into first to fourth gaps 5a to 5d by the first to third core members 3a, 3b, 3c. The first and second gaps cover these gaps 5a to 5d.
Are wound. A flat core member 4 is provided at the tip of each leg. Furthermore, the first leg 11
Each of the a, 12a and the second leg portions 11b, 12b is formed in a shape in which the lateral cross-sectional area B at the distal end is smaller than the lateral cross-sectional area A at the proximal end.

As described above, according to each of the first to fourth embodiments, one or a plurality of coils each having a plurality of gaps therein are provided, and at least one of a pair of magnetic cores opposed to each other via the gap is provided at a base end. Since the shape is formed such that the lateral cross-sectional area of the tip portion is smaller than the lateral cross-sectional area of the portion, the concentration of leakage magnetic flux can be dispersed over the entire length of the coil. Thereby, abnormal heat generation of the coil can be prevented.

In each of the above embodiments, the magnetic core member arranged in the gap is set to have a size within the area of the core end portion of the gap forming region. So that it does not leak.

FIG. 5 shows a coil device having a conventional structure for comparison. The coil device 1 has a first U-shaped magnetic core 19 having a leg 19a and a second U-shaped magnetic core 19 having a leg 20a. Magnetic core 20
The coil 21 is wound so as to cover the inside of the gap 5 formed between the opposing legs 19a and 20a. The opposing legs 19a and 20a are formed in a shape having the same lateral cross-sectional area over the entire length.

The following table shows the results of measuring the temperature of each part of the coil device obtained by each embodiment in comparison with the conventional coil device. The positions of each part were determined using a test apparatus 30 as shown in FIG. (Test conditions: frequency 1000KHz, 0.8A sine wave, ambient temperature 40 ° C) As is clear from the above table, according to each embodiment of the present invention, a decrease in temperature is observed in any of the coil center portion X, the coil end portion Y, the core portion Z, and the surrounding W as compared with the conventional example. Therefore, abnormal heat generation of the coil can be prevented. In addition, since assembly can be easily performed, cost can be reduced.

In each embodiment, in at least one of the pair of magnetic cores facing each other with a gap therebetween, the shape in which the lateral cross-sectional area of the distal end is smaller than the lateral cross-sectional area of the base end is an example in which the magnetic core is formed in a curved shape. Although shown in the drawings, the present invention is not limited to these shapes, and may have shapes as shown in FIGS. 7 (a) to 7 (c). That is, FIGS. 7 (a), (b), (c)
Are tapered portions 22a and 23a, 22b and 23b, 22c and 23c so that the inclined surface becomes gradually gentle around a pair of opposing legs 22 and 23.
This shows an example in which the lateral cross-sectional area B at the distal end is made smaller than the lateral cross-sectional area A at the base end by forming. Further, shapes as shown in FIGS. 8A to 8H can be taken. That is, the eighth
FIG. 7A shows spherical surfaces 25a and 26a on opposite ends of a pair of legs 25 and 26, respectively.
FIG. 8 (b) shows a shape in which curved surfaces 25b and 26b are similarly formed to reduce the cross-sectional area toward the facing surface, and FIG. 8 (c) shows curves 25c and 26c. Shape,
FIG. 8 (d) is a shape having peaked surfaces 25d and 26d, FIG. 8 (e) is a shape having notched surfaces 25e and 26e, and FIG. 8 (f).
Is a shape having stepped surfaces 25f and 26f, FIG. 8 (g) is a shape having square surfaces 25g and 26g formed on the upper surface of a truncated cone, and FIG. 8 (h).
Indicates a shape in which square pyramid surfaces 25h and 26h are formed.

Although the embodiment has been described with an example in which up to three coils are provided, it is also possible to provide four or more coils.

[Effects of the Invention] As described above, according to the present invention, it has high saturation resistance to magnetic flux, further reduces the influence of noise on peripheral devices, reduces leakage magnetic flux generated around the gap,
Thus, it is possible to provide a coil device that prevents abnormal heat generation of the coil around the gap and that is inexpensive and has improved reliability.

[Brief description of the drawings]

FIGS. 1 (a) and (b) to FIGS. 4 (a) and (b) show a coil device according to a first embodiment, a second embodiment, a third embodiment, and a fourth embodiment, respectively. FIG. 5 is a schematic diagram showing a conventional example, FIG. 6 is an explanatory diagram of a temperature measuring method of each part of a coil device, and FIGS. 8 (a) to 8 (h) are schematic diagrams showing other modified examples of the shape of the magnetic core used in the coil device of the present invention. . 1 ... coil device, 2,8 ... magnetic core, 5,5a to 5d ... gap, 9,11 ... first magnetic core, 10,12 ... second magnetic core, 6,7 ... coil, 2a , 2b, 9a, 9b, 10a, 10b, 11a, 11b, 12a, 12b ... leg, 30 ... test equipment, A ... lateral cross-sectional area of base end of leg, B ... leg The lateral cross-sectional area of the tip.

Claims (2)

(57) [Claims] A magnetic core is formed from a magnetic core having a gap in which a magnetic core portion has no contact in the magnetic path, and coils wound respectively so as to include a region of the magnetic core forming the gap. In the coil device, one or two or more magnetic core members are arranged in the gap to form a plurality of gaps, and at least one of core portions located at both ends of a region where the plurality of gaps is formed is a base end. The shape is such that the cross-sectional area of the distal end is smaller than the cross-sectional area of the proximal end as a shape that becomes narrower from the portion toward the center of the distal end, and the lateral cut of the core member disposed in the gap is reduced. A coil device having an area smaller than a lateral cross-sectional area of a tip portion of a magnetic core of the gap forming portion. 2. A magnetic core having a plurality of gaps in which a magnetic path is formed and whose magnetic core portions are not in contact at different positions in the magnetic path, and wound around the core so as to include a region forming the gap. And a coil device comprising at least one magnetic core member disposed in the gap to form a plurality of gaps, and a magnetic core portion located at both ends of a region where the plurality of gaps are formed. At least one has a shape in which the lateral cross-sectional area of the distal end portion is smaller than the lateral cross-sectional area of the proximal end portion as a shape that becomes thinner from the proximal end portion toward the center of the distal end portion, and a magnetic core disposed in the gap. A coil device, wherein a lateral cross-sectional area of a member is smaller than a lateral cross-sectional area of a tip portion of a magnetic core of the gap forming portion.