JP2001274026A - Electromagnetic inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin electromagnetic inductor which can be mounted on a wiring board with a small mounting area. SOLUTION: This electromagnetic inductor is constituted in such a way that windings 11 and 12 are wound around a flat bobbin 1 having an axial dimension D1 smaller than its diametral dimension D2 and the middle leg sections 24 and 24 of a pair of F-shaped core pieces 23 and 23 are inserted into the center holes 20 and 22 of the bobbin 1. At the same time, the outer leg sections 27 and 27 of the core pieces 23 are positioned outside the windings 11 and 12 in the diametral directions of the windings 11 and 12 on the outside of the bobbin 1 and the arm sections 31 and 31 of the pieces 23 are extended in the diametral directions of the windings 11 and 11 and parallelly faced to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an electromagnetic inductor such as a transformer mainly used for driving a magnetron using an inverter.

[0002]

2. Description of the Related Art FIG. 6 shows an inverter-type high-frequency heating device (microwave oven) disclosed in Japanese Patent Publication No. 7-40465, in which a commercial power supply 61 is rectified and smoothed by a rectifier circuit 62. It is converted to a high frequency AC current of 20 kHz or more and supplied to a primary winding 64p of a transformer 64 having a core with a gap. Transformer 64-2
The high-frequency output voltage of the next winding 64s is rectified and smoothed by the half-wave rectifier circuit 65, and is supplied to the magnetron 66 as a DC high voltage. The magnetron 66 whose heater is driven by the heater winding 64h of the transformer 64 receives a high DC voltage and generates a microwave.

FIG. 8 is a sectional view showing the structure of the transformer 64. A bobbin 70 has a primary winding 64p and a secondary winding 64.
s and the heater winding 64h are wound apart from each other in the axial direction. The U-shaped core pieces 71 and 72 have one magnetic leg inserted into the cylindrical portion 70s of the bobbin 70 and a thickness G formed in the cylindrical portion 70s.
The spacers 70g are opposed to each other to form a square-shaped core 75 having gaps 73 and 74 between the opposed end faces of the two magnetic legs, respectively.

[0004]

However, in the transformer 64, the magnetic circuit C is formed only on one side (the left side in the figure) of the primary and secondary windings 64p and 64s. Since the arm portions 71a, 72a between the magnetic legs on both sides of the two core pieces 71, 72 forming the magnetic circuit C are relatively separated from each other and are positioned in parallel with each other, the magnetic loss increases and a strong magnetic flux is formed. Can not do it. Therefore, in order to obtain a required voltage, the primary and secondary windings 6
The number of turns of 4p, 64s cannot be reduced. Therefore,
The transformer 64 has two windings 6 in order to form a flat shape.
When the winding width (length in the axial direction) of 4p, 64s is reduced,
Since the winding thickness (radial thickness) of both windings 64p and 64s is increased in order to secure the number of turns required to obtain a predetermined voltage, the lateral dimension of the transformer 64 is increased. As a result, the transformer 64 having the above configuration cannot be downsized.
The mounting area on the wiring board increases.

The transformer 64 has a primary winding 64.
A spacer 70g for forming a gap 73 is provided at a position surrounded by p, and one U-shaped core piece 71, 72 of each of the core pieces 71, 72 is used by using U-shaped core pieces 71, 72 having different lengths of the magnetic legs. Is inserted into the cylindrical portion 70s of the bobbin 70. Therefore, two types of core pieces 71 and 7 having different shapes are provided.
2 is required, the types of core pieces 71 and 72 increase,
Manufacturing costs increase.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an electromagnetic inductor which can be reduced in height while suppressing an increase in a mounting area when mounted on a wiring board. I do.

[0007]

Means for Solving the Problems In order to achieve the above object, the electromagnetic inductor of the present invention has a winding mounted on a flat bobbin whose axial dimension is shorter than its radial dimension. The center leg of the pair of F-shaped core pieces is inserted into the center hole of the bobbin, and the outer leg is positioned outside the bobbin in the radial direction of the winding. Arm portions extend in the radial direction of the winding and face each other in parallel. Here, the F-shape refers to a shape that presents an F-shape in a stereoscopic view, and does not include a shape in which the center portion and the outer peripheral portion of the disk are provided with legs protruding in the axial direction, and the F-shape is obtained only in side view.

In this electromagnetic induction device, the middle leg of both core pieces,
In addition to the magnetic circuit that passes through the arm and the outer leg, a magnetic circuit that passes through the gap between the middle leg of the two core pieces, the arm, and the tip of the two arms, is formed. It is less than a letter core and a strong magnetic flux is formed by the two magnetic circuits. Furthermore, since the bobbin has a flat shape in which the axial dimension is shorter than the radial dimension, the interval between the arm portions of the pair of core pieces is reduced, so that the magnetic flux formed in the magnetic circuit is further increased. . As a result, this electromagnetic inductor has excellent magnetic properties, and
Even in the case where the winding width (length in the axial direction) of the secondary and secondary windings is reduced to be thin, the number of turns of the primary and secondary windings required to obtain a predetermined voltage can be reduced. Can,
The horizontal dimension, that is, the dimension along the radial direction of the bobbin is reduced by that much, and the size can be reduced, and the mounting area when mounting on the wiring board can be suppressed from increasing.

In a preferred embodiment of the present invention, a primary winding and a secondary winding are mounted on a bobbin so as to be axially separated from each other as the windings, and a center leg of the pair of core pieces and A gap is formed between the opposing tip surfaces of each of the outer legs. According to this configuration, an electromagnetic inductor having characteristics that are hardly magnetically saturated due to the presence of the gap can be obtained.

[0010] The coupling coefficient between the primary winding and the secondary winding is 0.1.
Preferably, it is set between 6 and 0.8. By applying the electromagnetic induction device having this configuration to an inverter-type high-frequency heating device, a high-frequency choke on the secondary side becomes unnecessary.

In a preferred embodiment of the present invention, a lead wire is led out from an end of the primary winding attached to the bobbin, and the leading end of the lead wire is connected to a terminal block mounted on a wiring board. A terminal connected by screwing or insertion is attached, and an end of the secondary winding is connected to a pin terminal fixed to a bobbin and inserted into the wiring board.

According to the above configuration, it is easy to connect the primary winding, which is usually formed of a thick conductor, to the wiring board. In addition, since the end of the secondary winding, which is usually formed of a thin conductive wire, is connected to the pin terminal fixed to the bobbin, the end of the secondary winding, which becomes a high voltage, is attached to the wiring board at the time of attachment. There is no risk of unexpected swinging and contact with surrounding conductors.

In a preferred embodiment of the present invention, at least a part of the winding is fixed by heat-sealing a fusion wire in which a core wire is coated with a fusion material capable of being heat-sealed in advance. The fixed winding is mounted on a bobbin. As a result, the winding that has been aligned and wound in advance and is attached to the bobbin is mounted on the bobbin, so that the winding width (length in the axial direction) is set.
The winding can be easily mounted on a small bobbin.

[0014]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a magnetron driving transformer 100 according to an embodiment of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a longitudinal sectional view, and FIG. 4 is an exploded front view. First, as shown in FIG. 4, the resin bobbin 1 is composed of a first bobbin piece 2 and a second bobbin piece 3 divided in the axial direction. In the first bobbin piece 2, three disc-shaped flanges 4, 7, and 8 are integrally formed on the outer peripheral surface of the cylindrical tube portion 14 in a parallel arrangement. 1 having a first collar 4 and a second collar 7 at both ends
A primary winding 11 is wound in a cylindrical shape around the next winding frame 9, and a heater winding 13 is provided on a heater winding frame 10 having a second flange 7 and a third flange 8 at both ends. It is wound one turn.

On the other hand, the second bobbin piece 3 is integrally formed with a disk-shaped flange 18 on the outer peripheral surface of the central short cylindrical portion 17. First
Secondary bobbin frame 1 which is connected to bobbin piece 2 and has a flange 18 at each end and a third brim 8 of first bobbin piece 2
9 is formed, around which the secondary winding 12 is wound. The secondary winding 12 is one in which a fusion wire in which a heat fusion material is coated on an electric wire as a core wire is aligned and wound in a cylindrical shape in advance, and is fixed by heat fusion. The secondary winding 12, the primary winding 11, and the heater winding 13 are positioned displaced in the axial direction of the bobbin 1. When assembling the secondary winding 12,
Prior to connecting the second bobbin piece 3 to the first bobbin piece 2, the secondary winding 12 is previously mounted on the outer peripheral surface of the short tube portion 17, and in this state, the short tube portion 17 is brought into the first position. The bobbin piece 2 is fitted on the outer peripheral surface of the cylindrical portion 14.

As shown in FIG. 2, the bobbin 1 of the transformer 100 has an axial dimension D1 shorter than the radial dimension D2, and has a flat and thin shape. Here, the axial dimension D1 is an axial length of a portion where each of the windings 11 to 13 including the flanges at both ends of the bobbin 1 is mounted, and the radial dimension D2 is a plurality of flanges 4,7. , 8,18.

The center hole 20 inside the cylindrical portion 14 of the first bobbin piece 2 and the center hole 22 inside the short cylindrical portion 17 of the second bobbin piece 3 have the same diameter. When 3 is connected as described above, it becomes one central hole as the bobbin 1. As shown in FIG. 1, four guide ribs 21 projecting radially inward at 90 ° intervals are formed on the inner surface of the center hole 20 of the first bobbin piece 2.

As shown in FIG. 3, the core piece 23 has a cylindrical middle leg 24 substantially at the center of the arm 31 and a polygonal or cylindrical outer leg 27 having a square or larger shape at one end. It protrudes so as to extend in parallel in the same direction, and has an F-shape. A pair of F-shaped core pieces 23, 23 having the same shape and the same size, which constitute the core CR,
4 and 24 are inserted into the center holes 20 and 22 along the guide ribs 21 from both sides of the bobbin 1, and the outer legs 27 and 27 are opposed to each other outside the bobbin 1 so as to be primary and secondary.
They are arranged so as to be located radially outside the next windings 11 and 12. The two core pieces 23, 23 are attached to the bobbin 1 by being clamped and fixed from both sides in the axial direction by a U-shaped pressing spring 28 in the above arrangement.

When the pair of F-shaped core pieces 23, 23 are attached to the bobbin 1, the middle legs 24, 24 of each of the core pieces 23, 23 face each other, and a gap between the tip surfaces thereof is formed. Further, gaps 29, 30 are formed between the tip surfaces of the outer legs 27, 27, respectively. Thus, 1
The coupling coefficient between the secondary winding 11 and the secondary winding 12 is 0.6 to 0.8.
, Leakage inductance is provided on the secondary winding 12 side, and the secondary-side high-frequency choke coil required for the conventional magnetron inverter circuit is not required. The gap 29 is located inside the cylindrical portion 14 where the primary and secondary windings 11 and 12 of both bobbin pieces 2 and 3 are applied. Note that gap 2
Although the sizes of 9, 30 are appropriately set, zero, that is, the tip surfaces of the middle leg portions 24, 24 and the tip surfaces of the outer leg portions 27, 27 may contact each other.

The arms 31, 31 of the pair of F-shaped core pieces 23, 23 have a rectangular parallelepiped shape having a width substantially equal to the outer diameter of the middle leg 24, as shown in FIG. As shown in FIG. 3, the windings 11 to 13 extend in the radial direction and face each other in parallel, and at this position, the core housing portions 32 and 33 formed on the first and second bobbin pieces 2 and 3 It is stored in. Both ends of the arm portions 31, 31 of the core pieces 23, 23 are located radially outward of the outer diameter portions of the windings 11 to 13.

In the primary winding 11, the lead wire (lead wire) 11 a at the beginning of winding shown in FIG. 1 is pulled out from a lead portion 34 formed of a radially extending notch groove in the first bobbin piece 2. While being locked by the locking portion 37, the lead wire (lead wire) 11 b at the end of winding is drawn out from the drawing portion 34 and locked by the locking portion 38.
A flag terminal 39 is attached to the end of the leading wire 11a at the start of winding, and a round terminal 40 is attached to a terminal of the leading wire 11b at the end of winding. Conversely, the round terminal 40 may be attached to the end of the leading wire 11a at the beginning of the winding, and the flag terminal 39 may be attached to the terminal of the leading wire 11b at the end of the winding. The primary winding 1
1 is connected to the terminals 3a and 11b.
Instead of using the components 9 and 40, the components may be directly connected to the wiring board on which the transformer 100 is mounted by soldering.

On the other hand, as shown in FIG. 2, the lead wires 12a, 12b of the secondary winding 12 are inserted into and fixed to the second bobbin piece 3, and project from the pair of pin terminals 41, 42 in the axial direction.
And are connected by soldering. Further, the heater winding 13 has pin-type terminals 4 at both ends.
3 and 44 are attached to the heater reel 10 shown in FIG.
Turn wound.

The transformer 100 configured as described above includes:
For example, it is used for driving the magnetron 66 in the high-frequency heating device shown in FIG. 6, and in that case, it is incorporated into the high-frequency heating device in the following procedure. That is,
Transformer 100 has pin terminals 4 in connection holes provided in a wiring board on which a circuit pattern as shown in FIG.
1 and 42 are inserted and soldered, and the flag terminal 39 and the round terminal 40 are connected to the connection base provided on the wiring board by insertion and screwing, respectively, and the pin terminals 43 and 44 are connected. By inserting and connecting to the connection terminals provided on the wiring board, the wiring board is attached to the wiring board of the inverter circuit in a connected state. In addition, the above-mentioned circuit board has
Even if the full-wave rectifier circuit 47 of FIG. 7 is formed instead of the half-wave rectifier circuit 65 of FIG. 6, the transformer 100 can be mounted in a connected state.

According to the above configuration, both core pieces 2 shown in FIG.
A magnetic circuit C with low magnetic loss passing through the middle legs 24, 24, the arms 31, 31, and the outer legs 27, 27
In addition to 1, a magnetic circuit C <b> 2 is formed that passes through the middle leg portions 24, 24 of the core pieces 23, 23, the arm portions 31, 31 and the gap between the tips of the arm portions 31, 31. Therefore, the transformer 100 has the U-shaped core pieces 71, shown in FIG.
72, the magnetic loss can be reduced by forming two magnetic circuits C1 and C2 as compared with the transformer 64 that can form only one magnetic circuit C. That is, the magnetic flux passing inside the two windings 11 and 12 becomes strong. In addition, since the transformer 100 has a flat shape in which the bobbin 1 has an axial dimension D1 shorter than the radial dimension D2, the arm portions 31 of the pair of core pieces 23 are connected to each other. Since the distance is reduced, the magnetic flux formed in the magnetic circuits C1 and C2 is further increased.

As a result, the transformer 100 has excellent magnetic characteristics, so that the primary and secondary windings 11 and
12, the primary and secondary windings 11, 1 necessary to obtain a predetermined voltage even when the winding width is reduced.
2, the number of turns can be reduced, and the transverse dimension of the transformer 100, that is, the dimension along the radial direction of the bobbin 1, is reduced by that much, and the size can be reduced. Therefore, this transformer 100 can suppress an increase in the mounting area when mounting on the wiring board. Further, since both core pieces 23 have the same shape and the same dimensions, they can be molded using a common molding die. However, the two core pieces 23 may have different shapes or dimensions. In particular, the middle legs 24, 24
The positions of the gaps 29, 30 may be adjusted by making the lengths of the outer legs 27, 27 different from each other.

The ends of the secondary winding 12, which is usually formed of a thin wire, are connected to the pin terminals 41, 4 fixed to the bobbin 1.
2, the end of the secondary winding 12, which is at a high voltage, does not unexpectedly swing at the time of attachment to the wiring board, so that there is no possibility of contact with the surrounding conductor.

By the way, the secondary winding 12 is aligned and wound in advance and fixed as described above for the following reasons. That is, the bobbin 1 including the first and second bobbin pieces 2 and 3 is a synthetic resin molded product. Since the transformer 100 of the present invention is thin, the winding diameter of the primary winding 11 and the secondary winding 12 is larger than that of a thick type, so that the primary and secondary winding frames 9 and 19 are formed. Spit 4,7,
8, 18 become longer and thinner.

For this reason, heat distortion when molding the bobbin pieces 2 and 3 with a mold and the application of the windings 11 and 12 to the windings 11 and 12
The collar 4, due to the axial pressing force received from 12, etc.
Warpage tends to occur on 7, 8, and 18. In the case of the secondary winding frame 19 having a short winding frame width which is the length in the axial direction, the collars 8 and 18 are shown in FIG.
When a warp as shown by a two-dot chain line occurs, the winding frame width W changes in the radial direction. Therefore, when a thin electric wire used as the secondary winding 12 is wound in such a winding frame 19, the winding width becomes Is regulated by the winding frame width W, it is difficult to form a perfectly aligned winding, and the interlayer insulation characteristics are degraded. On the other hand, according to the present embodiment, since the secondary winding 12 is fixed in a completely aligned winding in advance, it is possible to mount the perfectly aligned secondary winding 12 even if there is a warp. As a result, interlayer insulation characteristics are improved.

The present invention can be applied to other electromagnetic inductors such as a choke coil and a reactor in addition to a transformer.

[0030]

In the electromagnetic inductor according to the present invention, the middle leg of a pair of F-shaped core pieces is inserted into the center hole of a flat bobbin whose axial dimension is shorter than the radial dimension. Since the outer legs are located outside the bobbin in the radial direction of the winding and the arm portions of the two core pieces extend in the radial direction of the winding and face each other in parallel, In addition to the magnetic circuit passing through the middle leg, the arm and the outer leg of both core pieces, a magnetic circuit passing through the gap between the middle leg, the arm and the tip of both arms of the core piece is formed. By reducing the distance between the arm portions of the pair of core pieces, the magnetic loss is reduced, and the magnetic flux formed by the core is further increased. Therefore, even in the case of a thin type, the number of turns of the primary and secondary windings required to obtain a predetermined voltage can be reduced, and the dimension of the bobbin along the radial direction is reduced by that much. It is possible to reduce the size and suppress an increase in the mounting area when mounting on a wiring board.

[Brief description of the drawings]

FIG. 1 is a plan view showing an electromagnetic inductor according to one embodiment of the present invention.

FIG. 2 is a front view of the embodiment.

FIG. 3 is a longitudinal sectional view of the embodiment.

FIG. 4 is an exploded front view of the embodiment.

FIG. 5 is a partially enlarged cross-sectional view showing a state in which the winding of the embodiment is mounted in a bobbin.

FIG. 6 is an electric circuit diagram showing a high-frequency heating device to which the electromagnetic induction device of the present invention can be applied.

FIG. 7 is an electric circuit diagram of a main part showing another high-frequency heating device.

FIG. 8 is a sectional view showing a conventional transformer (electromagnetic inductor).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bobbin, 11 ... Primary winding, 11a, 11b ... Lead wire (lead wire), 12 ... Secondary winding, 20, 22 ... Center hole of bobbin, 23 ... F-shaped core piece, 24 ... Middle leg part , 27 ...
Outer leg part, 29, 30 ... gap, 31 ... arm part, 39
... Flag terminal (terminal), 40 ... Round terminal (terminal), 41,
42: pin terminal, D1: axial dimension, D2: radial dimension.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) // H05B 6/66 H01F 27/24 E H 31/00 A (72) Inventor Hideaki Soma 1-chome Motejima, Nishiyodogawa-ku, Osaka-shi No. 12-20 Tabuchi Electric Co., Ltd. F term (reference) 3K086 AA10 BA08 CB12 CB13 CC01 DA03 DB01 FA02 FA03 FA04 5E043 AA02 AB01 BA01 EA01 EA05 EB03 EB05 EB06 5E044 AA08 AB01 BA04 BA06 BB02 BB09 BC02

Claims (5)

[Claims] 1. A winding is mounted on a flat bobbin whose axial dimension is shorter than its radial dimension, and a pair of middle legs of an F-shaped core piece are inserted into a center hole of the bobbin. In addition, the outer leg portion is located outside the bobbin in the radial direction of the winding, and the arm portions of the two core pieces extend in the radial direction of the winding and face each other in parallel. Inductor. 2. The winding according to claim 1, wherein
An electromagnetic device in which a secondary winding and a secondary winding are mounted on a bobbin so as to be spaced apart in the axial direction, and a gap is formed between opposed end surfaces of the middle leg and the outer leg of the pair of core pieces. Inductor. 3. The electromagnetic inductor according to claim 2, wherein a coupling coefficient between the primary winding and the secondary winding is set between 0.6 and 0.8. 4. The lead wire according to claim 2, wherein a lead wire is led out from an end of the primary winding attached to the bobbin, and the leading end of the lead wire is screwed to a terminal block mounted on a wiring board. Alternatively, an electromagnetic inductor in which a terminal connected by insertion is attached, and an end of the secondary winding is connected to a pin terminal fixed to a bobbin and inserted into the wiring board. 5. A winding wire according to claim 1, wherein at least a part of the winding wire is arranged in advance by winding a fusion wire whose core wire is covered with a fusion material capable of heat fusion, and is fixed by heat fusion. An electromagnetic inductor in which this fixed winding is mounted on a bobbin.