JP2011222727A - Toroidal core, and high frequency toroidal coil and high frequency toroidal transformer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a toroidal core, a high frequency toroidal coil, and a high frequency toroidal transformer having excellent heavy current/high power performance by improving the manufacture thereof.SOLUTION: This toroidal core made of soft ferrite includes a large number of micromagnetic gaps disposed in a ring core at large, uniformly dispersed with a small span kept from each other. As means to realize the toroidal core, a large number of I-shaped soft ferrite cores 1 are arranged in the shape of a single layer or multilayer ring by adjoining each other to form one ring core 2. Each of micromagnetic gaps 5 is retained mutually between the I-shaped soft ferrite cores 1. By using the toroidal core as an ion core, the specific high frequency toroidal coil and high frequency toroidal transformer are formed.

Description

  The present invention relates to a toroidal core and a high-frequency toroidal transformer such as a high-frequency toroidal coil such as a high-frequency choke, a filter, a reactor, and an inductance element, and a high-current high-frequency induction heating transformer.

  A conventional ring-shaped toroidal core is formed of a magnetic steel plate (alloy soft magnetic material) such as ferrite (soft ferrite ceramic) or a silicon steel plate (see Non-Patent Document 1 and Patent Document 1).

Most of the practical soft ferrite ceramics from the early 1930s to the present are spinel type ferrite ceramics represented by the chemical formula MFe2 O4 (M is mainly a divalent metal ion). Ferrite cores have high electrical resistance, low eddy current loss, excellent performance in the high frequency band, and can be molded into molds, so they can be made into various shapes. Since the saturation magnetic flux density is smaller than that of the soft magnetic material (refer to pages 216 to 218 of Non-Patent Document 1), this point has been improved in recent years, and the magnetic permeability is high in the high frequency band, and the saturation magnetic flux density is It is expressed as MOFe2 O3 (M: divalent metal), which has features such as large, high specific electric resistance and low eddy current loss. Soft ferrites have been developed and used in large quantities as high-frequency magnetic materials.

  However, when the toroidal core is formed of this MOFe2 O3 soft ferrite, the saturation curve increases and the saturation point of the magnetic flux increases, but the magnetization curve becomes steep and the magnetic saturation becomes remarkable. In toroidal coils and toroidal transformers for high-frequency, high-current and high-power cores, the magnetic flux of the core quickly exceeds the saturation point due to the current flowing through the coil. Cannot be used properly except for. On the other hand, if the magnetic resistance is increased by providing a magnetic gap in the magnetic path, the magnetic flux of the core is reduced and the inclination of the magnetization curve is relaxed. If the distance of the magnetic gap becomes longer, the leakage magnetic flux increases during this time, resulting in poor efficiency. Further, the inductance of the coil is reduced, an excessive current flows through the coil, the temperature of the coil rises extremely, and there is even a risk of burning. Will occur. Further, in the production of a toroidal core, for example, after mixing raw materials and calcining, this is pulverized, granulated, molded, and fired, requiring a complicated and advanced manufacturing process (Non-Patent Document). 1 (see page 218), and the finished core has no flexibility in shape, and it is remade from the beginning each time the shape changes, or if not, the finished core is cut, cut, polished, etc. In order to ensure high quality, especially high-precision machining, it is necessary to carry out advanced processing. In any case, it takes considerable time and money, and it is inevitable that the cost is high even if appropriate equipment is required. .

  Next, a core made of an alloy-based soft magnetic material, that is, a magnetic steel plate such as a silicon steel plate, is usually radial by laminating a suitable number of magnetic steel plates having different diameters in the radial direction or by winding a suitable number of magnetic steel plates. A magnetic gap is formed in the magnetic path by laminating in the direction to form a ring, or by dividing into a plurality of parts from the beginning or after the ring is formed, or by inserting a slit (see Patent Document 1). Therefore, in the case of this core as well, the inclination of the magnetization curve is relaxed by the magnetic gap, so that it can be used for high frequency high current and high power, and eddy current can be electrically prevented.

However, in the state where a small number of magnetic gaps are unevenly distributed, the magnetic gap does not necessarily prevent the eddy current as a whole of the core, and a considerable amount of heat (resistance heat) is generated by the eddy current in the core. The eddy current loss, particularly in the high frequency band, cannot be sufficiently reduced. Furthermore, the magnetic flux may be biased and locally increased, which may cause heat generation. In addition, a large leakage magnetic flux is generated in the magnetic gap, and the efficiency is deteriorated. As a whole, the magnetic characteristics, particularly the magnetic characteristics in the high frequency band are deteriorated. In this case, of course, the above-described machining or the like is required, resulting in an increase in cost.

  By the way, the coil provided in the ring-shaped toroidal core is generally wound around the core when the core is completed, but this winding is not easy. The toroidal core is cut in a radial direction at a key point and divided into a plurality of parts, and each of the divided cores is wound in an air core state while bending the cylindrical coil into a ring shape. (See Patent Document 2), No. 2, a cylindrical bobbin having a coil wound around its outer periphery is butted at both ends and bent into a ring shape to form an air core toroid A coil is formed, the bobbin is once opened at both ends of the coil, a ribbon of magnetic steel sheet is fed into the bobbin from the opening, and the coil is wound spirally in the bobbin (Patent Document) Reference) have been developed.

  However, in the first means, in order to obtain the above-mentioned split core, the ring-shaped toroidal core once is subjected to precision machining such as cutting, cutting and polishing in a radial direction at a critical point, or special processing from the beginning. Therefore, it is necessary to follow the problems of the conventional ferrite cores and the cores made of alloy soft magnetic materials as described above. In addition, it is not easy to join the split surfaces of the split cores in a coil into which a plurality of split cores are inserted. Therefore, the product maintains certain electrical and magnetic characteristics. This is extremely difficult, and it is difficult to stably supply high-quality products. In addition, specifically, an amorphous nanocrystalline alloy made of Fe, Zr, Nb, B or the like made of a magnetic material is wound or punched into a predetermined shape and laminated after being laminated. By using a ring core, a toroidal coil that has a high saturation magnetic flux density and is difficult to be magnetically saturated can be formed. A thin ribbon of the amorphous nanocrystalline alloy is difficult to manufacture if it is too thin, but it must be at least 20 μm or less. The current loss cannot be ignored, and the high frequency characteristics are degraded (see paragraph number 0017 of Patent Document 2). And if the target ring core is thick, it is formed by winding a thin ribbon, and if it is thin, it is preferable to punch and laminate a thin plate (see the same paragraph number 0017). It does not come out.

  Next, in the second means, the ribbon of the magnetic steel sheet is drawn into the bobbin from the opening of the ring-shaped bobbin that has been once opened, and is spirally wound in the bobbin to form the ring core. This means cannot be directly applied to a hard core made of soft ferrite ceramic. In addition, since the ribbon of magnetic steel sheet has bending elasticity, it cannot be easily and smoothly retracted into the bobbin or spirally in the bobbin, and the appropriateness and accuracy of the entrainment are lacking. There is a risk of becoming. Furthermore, the ring core in this case may also generate eddy currents, particularly eddy current loss and heat generation in a high frequency band.

JP-A-2005-303001 JP 2001-68364 A Special table 2007-527607 gazette

Patent Office Edition Patent Map by Technology Field "Ferrite Ceramic" Japan Institute of Invention and Innovation Chapter 4 4.2 “Soft Ferrite Ceramic”

  The present invention aims to solve all the above-mentioned conventional problems.

  In order to achieve the above object, the toroidal core of the present invention is characterized in that a large number of minute magnetic gaps are uniformly distributed in a small span over the entire ring core. Small I-shaped cores are formed in one ring core by arranging them in a single-layer or multi-layer ring shape adjacent to each other.

  Thus, the high-frequency toroidal coil according to the present invention is formed by using the toroidal core as an iron core.

  The high-frequency toroidal transformer according to the present invention is formed by using the toroidal core as an iron core.

  As described above, the toroidal core of the present invention has a large number of minute magnetic gaps uniformly distributed over the entire core in a small span, so that the magnetic resistance of the magnetic path is required by the sum of these minute magnetic gaps. Therefore, the inclination of the magnetization curve can be relaxed, and it can be adapted for high frequency, high current and high power. And, all of these minute magnetic gaps are minute distances, and the leakage of magnetic flux from these minute gaps is very small, and even if all the gaps are summed up, the leakage magnetic flux does not become so large, ensuring good efficiency. In addition, the inductance necessary for the coil can be maintained, an excessive current flowing in the coil can be properly prevented, and the temperature rise of the coil can be suppressed low. In addition, the core's electrical resistance can generally be increased almost uniformly by a large number of minute magnetic gaps distributed uniformly in a small span throughout the core, and the eddy current loss of the core and the heat generated by the eddy current. In addition, the magnetic flux in the core can be prevented from being biased, and the core can be prevented from being heated due to the magnetic flux being excessively increased. Note that the toroidal core of the present invention is not limited to a circular shape, and can be formed in a substantially circular shape including a spiral, an elliptical shape, an oval shape, a rectangular shape, a polygonal shape, and the like.

  Also, in order to disperse a large number of minute magnetic gaps uniformly over the entire ring core in a small span, a large number of small I-shaped cores are arranged adjacent to each other in a single or multi-layered ring to form a single ring core. In addition, a large number of small I-shaped cores, such as small I-shaped soft ferrite cores that are mass-produced and are commercially available, are sufficient, and thus a toroidal core can be realized simply and accurately. It can be freely formed in any size, ensuring flexibility and adaptability to design changes, etc., and has the inconvenience of having to be recreated from the beginning each time the shape changes. Otherwise, high-quality toroidal cores can be manufactured easily, easily, quickly, and inexpensively without the need for cutting, cutting, polishing, etc. with precision machinery. Facilities without the need, it is possible to reduce the cost down. Therefore, the high-frequency toroidal coil using the toroidal core and the high-frequency toroidal transformer can be appropriately improved.

  Furthermore, if a large number of I-shaped cores are initially formed in an I-shaped core row by adhering them on a heat-resistant, electrically insulating, bendable adhesive tape, the I-shaped core row is formed in advance. It can be easily inserted into the air core portion of the ring-shaped air core coil, and can be formed into a ring core appropriately and accurately within the coil.

  Therefore, according to the toroidal core of the present invention, the toroidal core, the high-frequency toroidal coil, and the high-frequency toroidal transformer for high current / high power that have remarkably superior high-frequency performance compared to the conventional toroidal core, toroidal coil, and toroidal transformer are provided. It can be provided, their production can be improved, it can be provided at low cost, and the intended purpose can be achieved.

The top view which shows Example 1 which concerns on the toroidal core of this invention Side view of Example 1 The top view which shows Example 2 which concerns on the toroidal core of this invention Side view of Example 2 Process explanatory drawing in the said Example 1. Cutting plan view showing a fourth embodiment of the high frequency toroidal transformer of the present invention Cut front view of the fourth embodiment The perspective view which shows the leader line of the Example 4 Explanatory drawing which shows the rear assembly example of the ring core in Example 4 The top view which shows Example 5 which concerns on the high frequency toroidal transformer of this invention Front view of Example 5 Cut front view of the fifth embodiment Front view showing a usage example of Example 5

1 and 2 show a first embodiment of the toroidal core of the present invention. In the figure, 1 is a high frequency band represented by MOFe ₂ O ₃ (M: divalent metal). A small I-type core (hereinafter referred to as I-type soft ferrite core) made of soft ferrite having a high magnetic permeability, a high saturation magnetic flux density, a large specific electric resistance, and a small eddy current loss. The core is an appropriate size selected from among those with a length of 12.4 to 70.0 mm, a width of 4.85 to 31.6 mm, and a thickness of 1.5 to 4.6 mm that are mass-produced and are commercially available at a low price. Many of the same size are used.

  A large number of small I-type soft ferrite cores 1 are formed in one ring core 2 according to the process shown in FIG. That is, first, on the thin heat-resistant / electrical insulating / flexible adhesive tape 3, the above-mentioned many I-shaped soft ferrite cores 1 are adhered to each other on a common long surface one after another. Thus, the I-type soft ferrite core rows 4 arranged in a row are formed (step A). In the step A, (1) shows a plane related to the I-type soft ferrite core row 4, and (2) shows a side face related to the I-type soft ferrite core row 4. Next, this I-type soft ferrite core array 4 is wound in a single layer or multiple layer spiral shape with the adhesive tape 3 inside, and in the case of multiple layers, the minute magnetic gaps 5 are not overlapped as much as possible between the layers. In consideration from the beginning, it is wound (steps B to D) and formed into one ring core 2 (step E). In this step E, (1) shows the plane of the ring core 2 and (2) shows the side surface of the ring core 2. An appropriate jig may be used when winding the I-shaped soft ferrite core row 4 in a spiral shape. The ring core 2 may be fastened with a binding band around it, or may be molded with silicon resin, epoxy resin, or the like. A plurality of the finished ring cores 2 may be connected in the cylinder direction.

  In the ring core 2 formed in this way, minute magnetic gaps 5 are formed between the respective I-type soft ferrite cores, and these minute magnetic gaps 5 are uniformly distributed over the ring core 2 in a small span. Will be arranged. The leakage magnetic flux in these minute magnetic gaps 5 is extremely small and does not become very large even if the entire ring core 2 is combined, and the magnetic flux flowing through the ring core 2 is less likely to be demagnetized. In addition, since a coil is wound around the ring core 2, most of the small leakage magnetic flux from the ring core 2 to the outside is blocked by the coil.

  As a means other than FIG. 5, for example, without making an I-type soft ferrite core row once, the above-mentioned many I-type soft ferrite cores 1 are directly adjacent to each other on a common long surface on a jig. And by bonding them with an adhesive such as an electrically insulating silicon resin, epoxy resin or the like, the ring core 2 having a single or multi-layer spiral shape can be formed.

  3 and 4 show a second embodiment according to the toroidal core of the present invention. In this case, the arrangement of the large number of I-type soft ferrite cores 1 in the first embodiment is formed as a single layer or multiple layers. Except for this circular shape, it is the same as in the first embodiment, and the operation and effect are also the same.

  The third embodiment relates to a high-frequency toroidal coil using a soft ferrite toroidal core made of the above-described ring core 2 as an iron core, which is not shown, and a required winding around the soft ferrite toroidal core. A high frequency toroidal coil is formed by applying a wire. In this case, the advantage of the toroidal core made of soft ferrite is utilized, and the high frequency characteristics are remarkably excellent, and it can be obtained easily and inexpensively. The third embodiment can be configured as the fourth embodiment below.

  Example 4 relates to a high-frequency toroidal transformer using the finished soft ferrite toroidal core as an iron core. As shown in FIGS. 6 to 8, the soft coil toroidal core has a primary coil 6 attached thereto. And the high frequency toroidal transformer is comprised by winding the secondary coil 7. FIG.

  In this case, the primary coil 6 and the secondary coil 7 are edgewise coils made of insulation-coated rectangular copper wire, and both are formed in a ring shape by bifilar winding, and the ends of both the coils 6 and 7 are outward. The primary coil lead wires 8a and 8b and the secondary coil lead wires 9a and 9b are projected.

  The primary and secondary bifilar-wound edgewise coils 6 and 7 formed in this way have an outer space and a wide space, so that a suitable air-cooling flow path 10 in which cooling air naturally convects is formed on the outer periphery. At the same time, the edgewise coils 6 and 7 themselves serve as cooling fins, so that the coils 6 and 7 that rise in temperature when energized are well air-cooled. This air cooling combined with the excellent function of the ring core 2, that is, the above-described soft ferrite toroidal core, improves the performance of the high-frequency toroidal transformer, and promotes simplification, ease and cost reduction of production. Become. The same applies to oil cooling.

  By the way, in the fourth embodiment, the ring core 2 specifically shown in FIGS. 6 to 8 is formed by spirally winding the I-type soft ferrite core row 4 in FIGS. 1, 2, and 5 in the first embodiment. In this case, the ring core 2 may be assembled later with respect to the completed primary coil 6 and secondary coil 7. That is, as shown in FIG. 9, ring-shaped primary and secondary coils 6 and 7 are formed in advance using a jig or the like, and a part of the coil is expanded and opened, and this opening 14 is inserted into the primary / secondary coils 6 and 7 (step A), and further retracted into a spiral shape (step B). The ring core 2 is formed (step C).

At this time, the I-type soft ferrite core row 4 is twisted too much during insertion / retraction because a number of I-type soft ferrites 1 attached to the adhesive tape 3 also act as aggregates on the adhesive tape. In the coil, it can be smoothly wound with almost no hindrance, and can be formed on the ring core 2 appropriately and accurately even in the coil. In addition, by adjusting the width of the adhesive tape 3 to the situation in the coil at various places, the adhesive tape 3 serves as a guide for insertion / retraction and secures an appropriate position in the coil. Can serve as a spacer. After that, it is better to tighten with a binding band. You may mold with an epoxy resin etc.

  As shown in FIGS. 10 to 13, the fifth embodiment uses the circular ring core 2 of FIGS. 3 and 4 described in the second embodiment in the high-frequency toroidal transformer of the fourth embodiment, The coil 7 is formed in a plurality of divided secondary coils 11, and the secondary coil lead wires 9a and 9b are also divided into a plurality of divided secondary coil lead wires 12a and 12b, both of which are protruded upward and downward. Yes. In this case, a single or a plurality of divided secondary coils 11 may be selected and used, but they can be connected in series or in parallel through the divided secondary coil lead wires 12a and 12b.

  According to the fifth embodiment, the use as shown in FIG. 13 is also possible. That is, in the case of FIG. 13, one split secondary coil lead wire 12 a protruding upward in FIGS. 10 to 12 and the other split secondary coil lead wire 12 b protruding downward are respectively crimped terminals 13 a. , 13b are electrically connected. As a result, all the divided secondary coils 11 are electrically connected in parallel, and a low voltage and large current is possible between the crimp terminals 13a and 13b. Therefore, it is suitable for a high current high frequency induction heating transformer or the like.

  In each of the above-described embodiments, since the toroidal core is a soft ferrite toroidal core using a large number of small I-shaped soft ferrite cores 1, it is possible to exhibit the operational effects peculiar to soft ferrite. If these I-type soft ferrite cores are I-type cores made of an alloy-based soft magnetic material such as a magnetic steel plate, corresponding effects can be obtained.

1 I-type soft ferrite core 2 Ring core 3 Adhesive tape 4 I-type soft ferrite core array 5 Micro magnetic gap 6 Primary coil 7 Secondary coils 8a and 8b Primary coil lead wires 9a and 9b Secondary coil lead wire 10 Air cooling flow path 11 Division Secondary coil 12a, 12b Split secondary coil lead wire 13a, 13b Crimp terminal 14 Opening

Claims (3)

A toroidal core characterized in that a large number of minute magnetic gaps are uniformly distributed in a small span throughout the ring core. A high-frequency toroidal coil using the toroidal core according to claim 1 as an iron core. A high-frequency toroidal transformer using the toroidal core according to claim 1 as an iron core.