JP2003086437A - Electromagnetic inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic inductor, capable of improving insulation performance between a secondary winding and an outgoing line, without enlarging the bobbin width. SOLUTION: In the electromagnetic inductor with its windings wound around the bobbin in which a core is inserted, a primary winding 11 and a secondary winding 12 are wound around a bobbin 1T separately of each other in the direction of their axes, a lead-out wire 12a of an inside diameter side of the secondary winding 12 is led out in the direction of axis, pulled toward the inner radial direction than an inside periphery face 12c of the secondary winding 12, and a lead-out wire 12b of the outer radial side is led out, pulled more toward the outer radial direction than toward an outside periphery face 12d of the secondary winding 12.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic inductor such as a transformer. 2. Description of the Related Art FIG. 7 shows an inverter type high frequency heating apparatus (microwave oven) disclosed in Japanese Patent Publication No. 7-40465. A commercial power supply 61 is rectified and smoothed by a rectifier circuit 62. The inverter 63 converts the current into a high-frequency AC current of 20 kHz or more and supplies the AC current 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 64 s is rectified and smoothed by the half-wave rectifier circuit 65 and 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. 9 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 while being spaced 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 face each other through a spacer 70g having a thickness G formed in the cylindrical portion 70s. By doing so, a gap 7 is formed between the opposing tip surfaces of the two magnetic legs.
A square-shaped core 75 having 3,74 is formed, and a coupling coefficient between the primary winding 64p and the secondary winding 64s is set to 0.6 to 0.8, so that a leakage inductance is provided on the secondary winding side. And eliminates the need for a secondary-side high-frequency choke coil that was required for the conventional magnetron inverter circuit. [0004] However, in the transformer 64, the secondary winding 64 is used in order to improve insulation by increasing the insulation distance between the secondary winding 64s and its lead wire.
It is necessary to provide a jumping groove adjacent to the s in the axial direction for passing the lead wire, so that the axial dimension of the bobbin 70 increases. The present invention has been made in view of the above-mentioned conventional problems, and without increasing the axial dimension of the bobbin.
It is an object of the present invention to provide an electromagnetic inductor capable of improving insulation between a secondary winding and a lead wire thereof. [0006] In order to achieve the above object, an electromagnetic inductor according to the present invention comprises a bobbin in which a core is inserted, a primary winding and a secondary winding being arranged in an axial direction. The lead wire on the inner diameter side of the secondary winding is mounted radially away from the inner peripheral surface of the secondary winding in the radial direction and is drawn out in the axial direction. , Are drawn radially outward from the outer peripheral surface of the secondary winding. [0007] According to the above configuration, the insulation between the secondary winding and the lead wire is improved, so as to increase the insulation distance between the secondary winding and the lead wire as in the related art. In addition, there is no need to provide a jumping groove for passing the lead wire adjacent to the secondary winding in the axial direction. Therefore, it is possible to improve insulation properties between the secondary winding and the lead wire at the beginning and end of winding of the secondary winding without increasing the axial dimension of the bobbin. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a magnetron driving transformer 50T according to a first embodiment of the present invention,
FIG. 2 is a side view, FIG. 3A is a cross-sectional view, and FIG.
3 is a plan view of the T-shaped core CR, FIG. 3C is a side view taken along line CC in FIG. 3B, and FIG. 4 is a rear view. First, as clearly shown in FIG. 2, the resin bobbin 1T is formed integrally with a first bobbin portion 1aT and a second bobbin portion 1bT, and has a cylindrical tube portion 14. In the first bobbin portion 1aT, three disk-shaped flanges 4, 7, and 8 are integrally formed on the outer peripheral surface of the cylindrical portion 14 in parallel with each other.
A primary winding 11 is wound on a primary winding frame 9 (FIG. 3) having a first collar 4 and a second collar 7 at both ends in a cylindrical shape, and a second collar 7 is provided at both ends. The heater winding 10 (FIG. 3) having the
Is wound one turn. On the other hand, in the second bobbin portion 1bT, a disc-shaped flange 18 is integrally formed on the outer peripheral surface of the central cylindrical portion 14, and the flange 18 and the third bobbin portion 1aT of the first bobbin portion 1aT are formed at both ends. A secondary winding frame 19 (FIG. 3) having a collar 8 is formed, around which the secondary winding 12 is wound in an aligned winding. The secondary winding 12, the primary winding 11, and the heater winding 13 are displaced in the axial direction of the bobbin 1T. As shown in FIG. 2, the bobbin 1T of the transformer 50T has an axial dimension D1 shorter than the radial dimension D2, and has a flat and thin shape. Here, the axial dimension D1 is the axial length of the portion where each of the windings 11 to 13 is not included, including the flanges at both ends of the bobbin 1T, and the radial dimension D2 is 7, 8, 18
Is the maximum outside diameter. As shown in FIG. 3, the bobbin 1T is provided with a center hole 20, and the inner surface of the center hole 20 of the first bobbin portion 1aT has 90 ° intervals as shown in FIG. , Four guide ribs 21 projecting radially inward are formed. As shown in FIGS. 3 (B) and 3 (C), the T-shaped core piece 23T has a T-shape with a columnar leg 24T protruding substantially at the center of the arm 25T. Core C
The leg portions 24T, 24T of the pair of T-shaped core pieces 23T, 23T of the same shape and the same size constituting the R are inserted into the center hole 20 along the guide ribs 21 from both sides of the bobbin 1T. When the pair of T-shaped core pieces 23T, 23T are attached to the bobbin 1T, each of the core pieces 23T, 2T
The tip surfaces of the legs 24T, 24T of the 3T face each other, and a spacer 27 is interposed between the tip surfaces to form a gap 29 set by the thickness of the spacer 27. Due to the existence of the gap 29, an electromagnetic inductor having characteristics that are hardly magnetically saturated can be obtained. For example, legs 24T, 24T
Of the core pieces 23T, 23T are prevented from falling off from the bobbin 1T. The size of the gap 29 is determined by the primary winding 11 and the secondary winding 12.
Are set to be 0.5 to 0.9. In this case, the axial distance W1 between the primary winding 11 and the secondary winding 12 in FIG. 2 is set to 2 to 10 mm. Thus, the secondary winding 12 is provided with leakage inductance, and the high frequency choke coil on the secondary side, which is 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 the bobbin pieces 2T and 3T are applied. The size of the gap 29 may be zero, that is, the tip surfaces of the legs 24T may be in contact with each other. The primary winding 11 has a lead wire (lead wire) 11a at the beginning of winding shown in FIG.
Is pulled out from the drawer portion 34 formed of a radially extending notch groove, and is locked by the locking portion 37a.
The lead wire (lead wire) 11b at the end of the winding is
4 and is locked by the locking portion 37b. For example, the terminals of the lead wires 11a and 11b are fixed with solder and the connection terminals 39a and 3 extend in the radial direction (downward) of the winding.
9b are formed, and the connection terminals 39a and 39b are directly soldered to the wiring board K on which the transformer 50T is mounted. In the present invention, the lead wire 12a at the beginning of winding on the inner diameter side of the secondary winding 12, as shown in FIG. 4, is a lead portion formed of a radially extending cutout groove in the second bobbin portion 1bT. A rib protruding from 35 is drawn radially inward from the inner peripheral surface 12c of the secondary winding 12 and is provided on the outer end surface of the second bobbin portion 1bT, that is, the outer surface of the outermost flange 18. It is bent along 36, extends radially outward, is wound around one of the pair of pin terminals 41a, 41b inserted and fixed to the second bobbin portion 1bT, and is connected by soldering. . The pin terminals 41a and 41b protrude in the radial direction (downward) of the winding and are connected to the wiring board K. On the other hand, the lead wire 12b at the end of the winding on the outer diameter side of the secondary winding 12 is brought closer to the outside in the radial direction than the outer peripheral surface 12d of the secondary winding 12 from the drawing portion 35, and the notch It is pulled out from the portion, wound around the other pin terminal 41b, and connected by soldering. The lead wires 13a, 13b of the heater winding 13 are also wound around a pair of pin terminals 43a, 43b which are inserted and fixed to the second bobbin portion 1bT and project in the radial direction (downward) of the winding, respectively, and are soldered. Connected by As shown in FIG. 1, the first bobbin portion 1aT
A plurality of primary winding cooling holes 28 are formed in the collar 4 in FIG. 2 to enhance the cooling effect on the primary winding 11. The ground wire 45 passes through the inside of the center hole 20 of the bobbin 1T, and comes into contact with the two T-shaped core pieces 23T, 23T,
The terminal is connected to the wiring board K, and the two T-shaped core pieces 23T, 23T are grounded at once. Since the core band is not grounded as in the related art, the width is reduced and the cost is reduced. Phosphor bronze is preferably used for the ground wire 45 because it is a non-magnetic material and requires spring properties. The transformer 50T thus configured is
For example, it is used for driving the magnetron 66 in the high-frequency heating device shown in FIG. 7, and in that case, it is incorporated into the high-frequency heating device in the following procedure. That is,
The transformer 50T is soldered by inserting the pin terminals 41a and 41b into connection holes provided in the wiring board K on which the circuit pattern as shown in FIG. 7 is formed, and soldering the terminals 39a and 3b.
9b is directly connected to a connection hole provided on the wiring board K by soldering, and the pin terminals 43a and 43b are inserted and connected to connection terminals provided on the wiring board K, thereby connecting the wiring of the inverter circuit. It is attached to the substrate K in a connected state. It should be noted that even if the full-wave rectifier circuit 67 of FIG. 8 is formed on the circuit board in place of the half-wave rectifier circuit 65 of FIG.
Can be attached in a connected state. According to the above configuration, as shown in FIG. 3, no core body exists on the side of the windings 11, 12, and 13.
The transverse dimension of the transformer, that is, the dimension along the radial direction of the bobbin 1T is reduced accordingly. Moreover, since the bobbin 1T has a flat shape, the winding widths of the primary and secondary windings 11 and 12 are small and thin, the pair of T-shaped core pieces 23T,
The space between the 23T arms 25T, 25T is reduced. Also, legs 24T, 24 of both core pieces 23T, 23T.
T and two magnetic circuits C passing through the arm portions 25T, 25T
1 and C2 are formed. Therefore, this transformer 50T
The magnetic loss is smaller than that of the transformer 64 in which only one magnetic circuit C can be formed by using the U-shaped core pieces 71 and 72 shown in FIG.
The magnetic flux passing through 24T, that is, the magnetic flux linked to both windings 11 and 12 becomes stronger. In addition, the transformer 50T
Since the bobbin 1T has a flat shape in which the dimension D1 in the axial direction is shorter than the dimension D2 in the radial direction, the interval between the arm portions 25T of the pair of T-shaped core pieces 23T, 23T becomes smaller. The magnetic flux of the magnetic circuits C1 and C2 is further increased. As a result, the transformer 50T has excellent magnetic characteristics, so that the primary and secondary windings 11,
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 50T, that is, the dimension along the radial direction of the bobbin 1T, is reduced by that much, and the size can be reduced. Moreover, the wiring board K
Are formed to extend in the radial direction of the winding.
Therefore, this transformer 50T can suppress an increase in the mounting area when mounting on the wiring board K. Also, since both T-shaped core pieces 23T, 23T have the same shape and the same dimensions, they can be formed using a common forming die. However, the two core pieces 23T, 23T may have shapes or dimensions different from each other. In particular, the position of the gap 29 and the coupling coefficient may be adjusted by making the lengths of the legs 24T, 24T different from each other. An end of the secondary winding 12, which is usually formed of a thin conductor, is connected to a pin terminal 41 fixed to the bobbin 1T.
Since they are connected to the terminals 41a and 41b, 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 K, so that there is no possibility of contact with the surrounding conductor. In the present invention, the bobbin portion 1bT is provided with a draw-out portion 35 formed of a cutout groove extending in the radial direction.
From the inner peripheral surface 1 of the secondary winding 12
Pull out radially inward from 2c and draw out 1 at the end of winding
Since 2b is drawn radially outward from the outer peripheral surface 12d of the secondary winding 12 and connected to the pin terminals 41a and 41b, a winding cross between the lead wires 12a and 12b and the secondary winding 12 is prevented. As a result, the insulation between them is improved. Therefore, as in the conventional case, the secondary winding 12
It is not necessary to provide a jumping groove for passing the lead wires 12a and 12b adjacent to each other in the axial direction. For this reason, without increasing the axial dimension of the bobbin 1T, the insulation characteristics between the lead wire 12a at the start of winding of the secondary winding 12 and the lead wire 12b at the end of winding and the secondary winding 12 are improved. Can be. FIG. 5 shows a second embodiment of the present invention. FIG.
3, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts. 5A is a cross-sectional view, FIG. 5B is a plan view of the L-shaped core CR, and FIG. 5C is a side view taken along line CC in FIG. 5B. Transformer 5 of this embodiment
0L uses a pair of L-shaped core pieces 23L, 23L shown in FIGS. 5 (B) and 5 (C), and the first and second bobbin portions 1aL integrally formed on the bobbin 1L accordingly. ,
The shapes of the core storage portions 32 and 33 of 1 bL are different. Other configurations are the same as those of the first embodiment, so that the illustration is omitted. As shown in FIGS. 5B and 5C, the L-shaped core piece 23L has a columnar leg 24L protruding from the base end of the arm 25L. A pair of L-shaped core pieces 23L, 2 having the same shape and the same size constituting the core CR.
3L, each leg 24L, 24L is inserted into the center hole 20 along the guide rib 21 from both sides of the bobbin 1L,
It is attached to bobbin 1L. The above pair of L-shaped core pieces 23L, 23L
Is attached to the bobbin 1L, each core piece 23L,
The legs 24L, 24L of the 23L face each other,
A gap 29 is formed between the tip surfaces. Thus, the coupling coefficient between the primary winding 11 and the secondary winding 12 is 0.5 to
By setting the ratio to 0.9, 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 provided between the primary and secondary windings 1 in both bobbin portions 1aL and 1bL.
It is located inside the cylindrical portion 14 to which the components 1 and 12 are applied. Note that the size of the gap 29 is appropriately set.
That is, the tip surfaces of the legs 24L may be brought into contact with each other. Also with the transformer 50L using the L-shaped core piece 23L, a relatively strong magnetic field is generated by the magnetic circuit C2 passing through the legs 24L and the arms of the core piece 23L, and the same effect as in the first embodiment is obtained. Is obtained. In the second embodiment, similarly to FIG. 4, the bobbin portion 1bL is provided with a lead-out portion 35 formed of a cutout groove extending in the radial direction, and the lead-out wire 12a which starts winding from the lead-out portion 35 is secondary-wound. The wire 12 is drawn radially inward from the inner peripheral surface 12 c of the wire 12, and the lead wire 12 b at the end of winding is drawn radially outward from the outer peripheral surface 12 d of the secondary winding 12, so that the pin terminal 4
1a, 41b. Therefore, similarly to the first embodiment, the secondary winding 12 can be connected between the secondary winding 12 and the lead wire 12a at the beginning and end of winding without increasing the axial dimension of the bobbin 1L. Can be improved in insulating properties. FIG. 6 shows a third embodiment of the present invention. FIG.
3, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts. 6A is a cross-sectional view, FIG. 6B is a plan view of the F-shaped core CR, and FIG. 6C is a side view taken along line CC in FIG. 6B. Transformer 5 of this embodiment
0F uses a pair of F-shaped core pieces 23F, 23F shown in FIGS. 6B and 6C, and in accordance with this, the first and second bobbin portions 1aF integrally formed on the bobbin 1F. ,
The shapes of the core storage portions 32 and 33 of 1 bF are different. Other configurations are the same as those of the first embodiment, so that the illustration is omitted. As shown in FIGS. 6 (B) and 6 (C), the F-shaped core piece 23F has a cylindrical middle leg 24F substantially at the center of the arm 25F, and a quadrangular or larger polygonal pillar or circle at one end. The column-shaped outer leg portions 26F are provided so as to protrude so as to extend in parallel in the same direction, and have an F-shape. A pair of F-shaped core pieces 2 of the same shape and the same size constituting the core CR
3F and 23F, each of the middle legs 24F and 24F is inserted into the center hole 20 along the guide rib 21 from both sides of the bobbin 1F, and each of the outer legs 26F and 26F is connected to the bobbin 1F.
They are arranged so as to be opposed to each other outside of F and radially outside the primary and secondary windings 11 and 12. When the above-mentioned pair of F-shaped core pieces 23F, 23F are attached to the bobbin 1F, each of the middle legs 2 of each of the core pieces 23F, 23F.
4F and 24F are opposed to each other, and gaps 29 and 30 are formed between the distal end surfaces and between the distal end surfaces of the outer leg portions 26F and 26F, respectively. Also with the transformer 50F using the F-shaped core piece 23F, a stronger magnetic field is generated as compared with the first embodiment by the magnetic circuit C3 passing through the leg 24F and the arm of the core piece 23F, which is more excellent. Magnetic properties are ensured. In the third embodiment, similarly to FIG. 4, the bobbin portion 1bF is provided with a lead-out portion 35 formed of a cutout groove extending in the radial direction, and the lead-out wire 12a which starts winding from the lead-out portion 35 is secondary-wound. The wire 12 is drawn radially inward from the inner peripheral surface 12 c of the wire 12, and the lead wire 12 b at the end of winding is drawn radially outward from the outer peripheral surface 12 d of the secondary winding 12, so that the pin terminal 4
1a, 41b. Therefore, similarly to the first embodiment, the secondary winding 12 is connected between the secondary winding 12 and the lead wire 12a at the beginning and end of winding without increasing the axial dimension of the bobbin 1F. Can be improved in insulating properties. The present invention is applicable not only to a transformer for driving a magnetron but also to other electromagnetic inductors such as a choke coil and a reactor. According to the present invention, the insulation between the secondary winding and the lead wire is improved, so that the connection between the secondary winding and the lead wire is improved as in the prior art. In order to increase the insulation distance, it is not necessary to provide a jumping groove for passing the lead wire adjacent to the secondary winding in the axial direction. For this reason, without increasing the width of the bobbin, the insulation characteristics between the lead wire at the start of winding of the secondary winding and the lead wire at the end of winding and the secondary winding can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of an electromagnetic inductor according to a first embodiment of the present invention. FIG. 2 is a side view of the embodiment. FIG. 3A is a sectional view taken along line III-III in FIG.
(B) is a plan view of the T-shaped core CR, and (C) is a side view taken along line CC in (B). FIG. 4 is a rear view of the embodiment. FIG. 5A is a cross-sectional view of an electromagnetic inductor according to a second embodiment of the present invention, FIG. 5B is a plan view of an L-shaped core CR,
(C) is a side view taken along line CC in (B). FIG. 6A is a cross-sectional view of an electromagnetic inductor according to a third embodiment of the present invention, FIG. 6B is a plan view of an F-shaped core CR,
(C) is a side view taken along line CC in (B). FIG. 7 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. 8 is an electric circuit diagram of a main part showing another high-frequency heating device. FIG. 9 is a cross-sectional view showing a conventional transformer (electromagnetic inductor). [Description of Signs] 1T: bobbin, 1aT, 1bT: bobbin part, 4, 7,
8, 18 ... collar, 9 ... primary reel, 10 ... heater reel, 1
1 ... primary winding, 12 ... secondary winding, 11a, 11b, 12
a, 12b: lead wire (lead wire), 12c: inner peripheral surface of secondary winding, 12d: outer peripheral surface of secondary winding, 13: heater winding, 14: cylindrical portion, 19: secondary winding frame, 20: center hole of bobbin, 23T: T-shaped core piece, 29, 30: gap, 3
2: Core storage part, 34, 35 ... Drawer part, 39a, 39b
... Terminals, 41a, 41b ... Pin terminals, 43a, 43b ...
Pin terminal, 50T transformer, C1, C2 magnetic circuit,
D1: axial dimension, D2: radial dimension, K: wiring board.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Fumiaki Yamagata             5-5 Techno Park, Sanda City, Hyogo Prefecture Tabuchi             Electric Co., Ltd.

Claims (1)

Claims 1. A primary winding and a secondary winding are mounted on a bobbin into which a core is inserted while being spaced apart in the axial direction, and a lead wire on the inner diameter side of the secondary winding is provided. The radially inner side surface of the secondary winding is moved radially inward and is drawn out in the axial direction, and the lead wire on the outer diameter side is radially outwardly moved from the outer peripheral surface of the secondary winding. The electromagnetic inductor being drawn out.