JPH07235432A - Coil bobbin for transformer - Google Patents

Abstract

PURPOSE:To prevent the dispersion of an output characteristic by preventing the variation of the mutual inductance of both coils and the positional variation of the path of the leakage flux of each coil. CONSTITUTION:A primary bobbin 34 and a secondary bobbin 35 are molded at a predetermined distance G into one body with a square cylinder-like body 31, and an installation part 36 for a leakage iron core is formed between both bobbins 34, 35. A primary coil is constituted by winding a primary coil wire in the primary bobbin 34, and a secondary coil is constituted by winding a secondary coil wire in the secondary bobbin 35. Therefore, the mutual position between both bobbins is not changed, so that the mutual inductance is not changed. A pair of notches 37 which can be fitted so as not to move the leakage iron core are formed in the installation part 36. Therefore, the relative position between the leakage iron core and each coil is not shifted, and the position of the path of leakage magnetic flux is not changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil bobbin used for winding each coil wire of a primary coil and a secondary coil housed in a transformer case such as a neon transformer.

[0002]

2. Description of the Related Art Conventionally, a case 51 of a neon transformer has a primary coil 52 and a secondary coil 5 as shown in FIG.
3 is stored. Both coils 52 and 53 are configured by winding coil wires 56 and 57 around bobbins 54 and 55, respectively, and the primary side bobbin 54 and the secondary side bobbin 55 are separately configured. Each bobbin 54, 55 is inserted through and supported by the main leg 59 of the magnetic core 58 at a predetermined distance g.

In a neon transformer which is a magnetic leakage transformer, a leakage iron core 60 is arranged between a primary bobbin 54 and a secondary bobbin 55 so as to sandwich the main leg 59 of the magnetic core 58. The leakage iron core 60 forms a path for leakage magnetic flux from the coils 52 and 53, and
The neon transformer is prevented from burning when a short circuit occurs in the secondary coil 53. A pair of insulating spacers 61 are inserted and arranged between the leaky iron core 60 and the secondary bobbin 55. The insulating spacers 61 isolate the leaky iron core 60 and the secondary bobbin 55 from each other. The insulating spacer 61 is an elastic member and always presses the leaky iron core 60 toward the primary bobbin 54.

After filling the case 51 with a liquid insulating compound (not shown) and curing the compound, the entire primary coil 52 and secondary coil 53 are enclosed in the case 51. It was fixed. Although not shown in the drawings, pins are projected from the bobbins 54 and 55, the pins are soldered on the board, and then the boards are mounted in the case 51 so that the coils 52 and 53 are placed in the case 51. In some cases, the positioning was fixed.

[0005]

However, in the former case, since the bobbins 54, 55 are separately inserted through the main legs 59 of the magnetic core 58, the inflow pressure at the time of filling the case 51 with the insulating compound may be affected. The mutual position of both bobbins 54, 55 may fluctuate.

In the latter case, if the pins protruding from each bobbin 54, 55 are bent, the bobbin 54, 55 may be mounted on the board while the mutual positions of the bobbins 54, 55 are changed. there were.

Therefore, the distance g between the bobbins 54 and 55 varies from the design specification, and the coils 52 and 5 are
There was a problem that the mutual inductance of No. 3 changed and the output characteristics varied, and the brightness of the neon tube changed.

Further, when the mutual positions of the bobbins 54 and 55 change, the leakage iron core 6 located between the bobbins 54 and 55.
Since the coils 52 and 53 are displaced with respect to 0, there is a problem that the path of the leakage magnetic flux moves and the output characteristics vary.

On the other hand, even if the mutual positions of the bobbins 54 and 55 do not change, if the leakage iron core 60 is displaced, the passage position of the leakage magnetic flux of the coils 52 and 53 also changes, so that the output characteristics are improved. There was a problem that there was variation in.

Therefore, the first object of the present invention is to prevent mutual positional fluctuations of both bobbins that cause variations in output characteristics. Further, the second purpose is to prevent the positional deviation of the two coils with respect to the leakage iron core, which similarly causes the output characteristics to vary. Furthermore, the third purpose is to prevent the positional deviation of the leaky core with respect to each coil, which also causes the output characteristics to vary.

[0011]

In order to achieve the first object, the invention of claim 1 provides a bobbin of a primary coil and a bobbin of a secondary coil in a direction in which magnetic fluxes of both coils interlink. They were integrated at a predetermined distance.

In order to achieve the second object, the invention of claim 2 provides a bobbin of the primary coil and a bobbin of the secondary coil with a predetermined distance in a direction in which the magnetic fluxes of both coils interlink. Then, the bobbin and the bobbin are integrated to form a mounting portion for the leaking iron core.

Furthermore, in order to achieve the third object, the invention of claim 3 provides a bobbin of the primary coil and a bobbin of the secondary coil with a predetermined distance in a direction in which the magnetic fluxes of both coils interlink. Then, the bobbin is integrated with the bobbin to form a mounting portion for the leaky core, and the mounting portion is provided with a positioning means for immovably mounting the leaky core.

[0014]

That is, in the invention of claim 1, since both bobbins are integrated, mutual positions of both bobbins do not change, and mutual inductance of both coils does not change.

Further, according to the second aspect of the present invention, as long as the mutual positions of both bobbins do not change, the respective coils will not be displaced with respect to the leakage iron core mounted between both bobbins. Further, according to the third aspect of the present invention, the mutual position variation of both bobbins is prevented, and the movement of the leakage iron core mounted between both bobbins is restricted by the positioning means, so that the leakage iron core is displaced with respect to each coil. There is nothing to do.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a coil bobbin of a neon transformer will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, a neon transformer N
The main body case 1 has a substantially rectangular tubular shape with a bottom, and an opening 1a is provided at the lower end thereof. Also, as shown in FIG.
A locking recess 2 is formed near the opening 1a on the front side of the body case 1. And body case 1
A fixing metal fitting 3 for attaching and fixing the neon transformer N to an attachment portion (not shown) is attached to the rear surface side.

A substrate 5 on which a transformer body 4 described later is mounted is inserted into the body case 1 through the opening 1a. Long and thin spacers 6 that penetrate the substrate 5 and extend in both front and back directions are provided on the left and right sides of the upper end of the substrate 5, and a short and large diameter that extends only to the back side of the substrate 5 at the center of the substrate 5. Spacer 7 is provided. The spacers 6 and 7 ensure a desired space between the substrate 5 and the inner surface of the main body case 1 in the main body case 1. Although not shown, the substrate 5
An electric circuit of the neon transformer N including an inverter circuit and the like is provided on the upper side, and the primary side lead wire 8 derived from the power supply side is connected to the electric circuit.

A bushing 11 is inserted and disposed in the opening 1a of the main body case 1 through a fitting 10 that is bent to correspond to the left and right width of the opening 1a.
The bushing 11 includes a main body 13 having a pair of secondary-side lead wire insertion holes 12 formed therein, and a projecting piece 14 projecting from an upper portion of the rear surface of the main body 13, and the lower surface of the projecting piece 14 is formed. A locking step portion 15 is formed on the side. A cylindrical portion 17 having a primary-side lead wire insertion hole 16 is formed at the tip of the locking step portion 15.

A pair of positioning protrusions 18 are provided on the lower portions of the left and right side surfaces of the main body portion 13 so as to abut and engage with the edge of the opening portion 1a when the main body portion 13 is inserted into the main body case 1. A locking claw 19 is formed on the lower part of the front surface of the main body 13 so as to elastically engage with the locking recess 2 at the lower part of the front surface of the main body case 1 when it is inserted into the main body case 1. On the other hand, a locking groove 20 corresponding to the locking stepped portion 15 of the bushing 11 is provided at substantially the center of the mounting member 10.
Is cut out from the front end side, and a pair of screw holes 23 are formed at the base end portions of both the bending pieces 21, 22. Further, a screw hole 24 for connecting a protective earth terminal (not shown) is formed at the tip of the long bent piece 21 of the bent pieces 21, 22.

Therefore, as shown in FIG. 3, the bushing 1
1 is inserted into the opening 1a of the main body case 1 in a state of being supported from below by a fitting 10 that is fitted and locked to a locking step portion 15 of the projecting piece 14 via a locking groove 20. .
Further, both the positioning projections 18 are brought into abutting engagement with the edges of the opening 1a, and the locking claws 19 are positioned and locked at the positions where they are engaged with the locking recesses 2 on the front surface of the main body case 1. Then, at the same position, the bent pieces 21, 22 of the mounting bracket 10
Screw 2 that penetrates both sides of the body case 1 into the screw hole 23 of
5, the bushing 11 is inserted and fixed to the opening 1a of the main body case 1 together with the fitting 10.

Next, the transformer main body 4 mounted on the substrate 5 will be described. The transformer body 4 includes a coil bobbin 26, a primary coil 27 and a secondary coil 28, a magnetic core 29, and a leakage iron core 30. First, the contents of each component such as the coil bobbin 26 will be described.

The coil bobbin 26 is made of a thermosetting resin material such as phenol resin and has a rectangular cylindrical body 3.
As shown in FIG. 4, the outer surface of 1 is provided with a pair of collar portions 3 on the front end side.
2 are integrally formed, and eight flange portions 33 are integrally formed on the rear end side. Then, in the body 31, a space between the pair of flange portions 32 formed on the front end side is configured as a primary side bobbin 34, and each of the eight flange portions 3 formed on the rear end side.
A portion between 3 is configured as a secondary bobbin 35. Further, a predetermined distance G is secured between the bobbins 34, 35, and the mounting portion 36 of the leaky iron core 30 is attached to the bobbins 34, 3 respectively.
5 and the coil bobbin 26 are integrally formed.

As shown in FIGS. 5 and 6, the mounting portion 36 is formed with a pair of notches 37 as positioning means notched over the upper surface and both side surfaces of the body 31. Further, five pins P1 are projected in a row on the lower surface of the front end portion of the primary side bobbin 34, and a pair of pins P2 are projected in a diagonal line on the lower surface of both front and rear ends of the secondary side bobbin 35. Has been done. Further, a positioning protrusion 38, which serves as a mark in the mounting direction of the coil bobbin 26 when the coil bobbin 26 is mounted on a winding jig, is provided on the upper portion of the front end surface of the coil bobbin 26. The coil bobbin 26 may be formed by molding a thermoplastic resin material such as polybutylene terephthalate, and the number of the flange portions 32 and 33 of the primary and secondary bobbins 34 and 35 may be changed appropriately. It is also possible.

The primary coil 27 is a coil bobbin 2
Of the body 31 of No. 6, both flange portions 3 of the primary side bobbin 34
It is configured by winding three primary side coil wires 39 having a wire diameter of 0.5 mm between the two. Further, the secondary coil 28 has a wire diameter of 0.0 with respect to the secondary bobbin 35.
A single secondary coil wire 40 having a length of 8 mm is wound around the collar portions 33. The winding start end and the winding end end of each primary coil wire 39 are wound around the corresponding pins P1 on the lower surface of the front end of the primary bobbin 34. A winding start end of one coil wire 39 and a winding end end of another coil wire 39 are commonly wound around one pin P1 of the five pins P1. The winding start end and the winding end end of the secondary coil wire 40 are wound around the pair of pins P2 on the lower surface of the front end and the lower surface of the rear end of the secondary bobbin 35.
In the state where the coil wires 39 and 40 are wound, an insulating varnish is impregnated between both the collar portions 32 of the primary bobbin 34 and between the collar portions 33 of the secondary bobbin 35.
The coil wires 39 and 40 are insulated from each other.

The magnetic core 29 is a pair of single-phase three-leg iron cores made of ferrite, and has a substantially E-shaped plane. The main leg 29a provided at the center of the coil bobbin 26 is formed so as to be inserted into the body 31 of the coil bobbin 26. In this embodiment, the left and right width of the main leg 29a is formed to correspond to the space between the notches 37 formed in the body 31. A pair of side legs 29b are provided in parallel on both sides of the main leg 29a.

The leaky cores 30 are a pair of I-shaped cores made of ferrite, and are formed to have a thickness capable of being fitted into the notches 37 of the mounting portion 36. Then, in the state of being fitted in the cutout portion 37, the coils 27,
A passage for the leakage magnetic flux of 28 is formed, and a passage for letting out a short-circuit current when a short circuit occurs in the secondary coil 28 is formed.

Next, the mounting state of the transformer body 4 on the substrate 5 will be described. The coil bobbin 26 is connected to the primary bobbin 34 and the secondary bobbin 35, respectively.
9, 40 are wound and the primary side coil 2 is provided on the body 31.
7 and the secondary coil 28 are formed on the substrate 5
It is mounted on. In the same state, the pins P1 and P2 projecting from the lower surface of the coil bobbin 26 are penetratingly mounted on the board 5, and the pins P1 and P2 are soldered to the electric circuit formed on the board 5. Also, the substrate 5
Each pin P of the primary side bobbin 34 is connected via the above electric circuit.
1 is connected to the primary side lead wire 8. Further, both the pins P2 of the secondary bobbin 35 are connected to the secondary side lead wire 9 led out to the load side such as a neon tube through the secondary side lead wire insertion hole 12 of the bushing 11. .

Also, as shown in FIG. 1, the coil bobbin 26
The main legs 29a of each magnetic core 29 are inserted from the front and rear ends of
The end faces of the side legs 29b are joined together in a state of contacting each other. Then, in this state, the leaky iron core 30 is fitted in each notch 37 of the mounting portion 36 as shown in FIG. 6, and is positioned immovably in the notch 37.

Therefore, when a voltage of 100 V is applied from the primary side lead wire 8 in this mounted state, the secondary side coil 28 is excited via the primary side coil 27 and the magnetic core 29, and the secondary side lead wire 9 is excited. To a predetermined voltage (for example, 15
KV) is output to the load side. In addition,
An insulating compound (not shown) is filled in the body case 1 so that the substrate 5 is fixed in position in the case 1. The bushing 11 and the fitting 10 are inserted and fixed to the opening 1a of the main body case 1 before the insulating compound is solidified.

Next, the operation of the coil bobbin 26 of the neon transformer N configured as above will be described. First, by using a winding jig, the coil wires 39, 4 are attached to the primary bobbin 34 and the secondary bobbin 35 of the coil bobbin 26.
When winding 0, the coil bobbin 26 is mounted on the winding jig with the positioning protrusion 38 as a mark. Therefore,
The risk of mounting the coil bobbin 26 upside down with respect to the winding jig can be avoided, and the coil wires 39 and 40 are accurately wound so that the primary coil 27 and the secondary coil 28 are mounted on the body 31 of the coil bobbin 26. Can be formed.

Further, when the pins P1 and P2 are bent when the coil bobbin 26 is mounted on the substrate 5, the coil bobbin 26 is left on the substrate 5 as it is.
It will not be possible to mount it in the upper predetermined position. That is, since the mutual positions of both bobbins 34 and 35 do not change, the bent pins P1 and P2 do not correspond to the electric circuit on the board 5, and the pins P1 and P2 are not soldered to the electric circuit. . Therefore, unlike the case where both bobbins 34 and 35 are separate components, when the pins P1 and P2 are bent, the distance G between the bobbins 34 and 35 is not changed and mounted on the substrate 5. Further, for the same reason, there is no fear that the mutual position of both bobbins 34, 35 may be changed by the inflow pressure of the insulating compound filled in the main body case 1.

Therefore, the mutual inductance of the primary side coil 27 and the secondary side coil 28 does not fluctuate either, so it is possible to reliably prevent the occurrence of variations in the output characteristics due to variations in the inductance, and to prevent fluctuations in the brightness of the neon tube. can do.

Furthermore, as long as the mutual positions of the bobbins 34, 35 do not change on the substrate 5, the primary coil 2
7 and the secondary coil 28 are not positioned with respect to the leaky iron core 30 arranged in the mounting portion 36. Moreover, since the leakage iron core 30 arranged in the mounting portion 37 is immovably fitted in the cutout portion 37, the leakage iron core 30 may move and be displaced relative to the coils 27, 28. Nor.

Therefore, since the relative positions of the primary side coil 27 and the secondary side coil 28 and the leakage core 30 do not fluctuate, variations in the output characteristics due to the fluctuations of the leakage flux passage positions of the coils 27 and 28 also occur. It can be surely prevented.

Further, since the notch 37 acts as an insertion guide when the leaky iron core 30 is mounted, the work of assembling the leaky iron core 30 to the transformer body 4 can be easily performed. Moreover, since the leaky core 30 can be made immovable by the notch 37 formed in the body 31 without inserting and arranging other members such as insulating spacers, the number of members can be reduced and the work of assembling the leaky core 30 is complicated. Can be prevented.

In this embodiment, the leakage iron core 30 is used.
Is composed of a pair of I-shaped cores, but a U-shaped leakage core 41 as shown in FIG. 7 may be used. When this U-shaped leaky iron core 41 is used, the work of attaching the leaky iron core 41 to both the notches 37 can be performed only once, so that the work of assembling the transformer main body 4 can be performed promptly. or,
When there is a difference between the width between the legs of the U-shaped leaky iron core 41 and the width between the notches 37, a spacer made of resin or paper (not shown) is adhered to the inner surface of both legs of the U-shaped leaky iron core 41. It is also possible to adjust.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The same components as those in the first embodiment will be designated by the same reference numerals in the drawings, and duplicate description will be omitted.

The second embodiment differs from the first embodiment only in the structure of the positioning means. That is, in the first embodiment, the notch portion 37 constitutes the positioning means, but in the second embodiment, the pocket portion 44 formed by the guide ridge 42 and the receiving piece 43 protruding from both side surfaces of the body 31. This constitutes the positioning means. Therefore, in this second embodiment, in addition to the effects of the first embodiment, the body 3
Since the cutout portion 37 is not formed in the groove 1, the strength reduction of the coil bobbin 26 due to the formation of the cutout portion can be prevented.

When the U-shaped leaky iron core 41 is used, it is preferable to use the leaky iron core 41 having a width corresponding to the width of the body 31 as shown in FIG. Further, in this case, since the U-shaped leakage iron core 41 can be supported on the upper surface of the body 31, it is possible to omit the receiving piece 43 and configure the positioning means only with the guide ridge 42.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is also different from the above-mentioned embodiments only in the structure of the positioning means, and the same components as those in the above-mentioned embodiments are designated by the same reference numerals in the drawings and their duplicated description will be omitted. .

In the third embodiment, the collar portion 3 of the secondary bobbin 35 is provided on the upper surface and both side surfaces of the body 31 in the mounting portion 36.
A positioning step portion 45 is formed to bulge out from 3, and the step portion 45 constitutes a positioning means. Therefore, in the third embodiment, the U-shaped leaked iron core 4 is used instead of the I-shaped leaked iron core 30.
1 will be used. However, if a resin holder 46 as shown in FIG. 11 and FIG.
Since the I-shaped leaky iron core 30 can be fitted and held in the fitting frame 47 of No. 6, the I-shaped leaky iron core 30 can be used instead of the U-shaped leaky iron core 41. Therefore, in the third embodiment, in addition to the effects of the above-described respective embodiments, the notch 37 and the pocket 4 are provided.
The forming process of the coil bobbin 26 can be further simplified as compared with the case of forming 4, and the strength of the positioning means itself can be increased.

The present invention is not limited to the configuration of each of the above-described embodiments, but can be modified and implemented as follows. That is, it may be applied to a coil bobbin of a transformer for a gas appliance other than the neon transformer N or a transformer for a combustion appliance such as a fan heater. Further, in each of the above embodiments, the plane E type single-phase tripod core is used for the magnetic core 29, and the outer iron type transformer structure in which the coils 27 and 28 are arranged on the main leg 29a thereof is used. A core type may be used to form an inner iron transformer structure. If the transformer is of a low frequency type, it is more easily magnetized than ferrite and the coil wire 3
It is also possible to form the magnetic core 29 from silicon steel capable of reducing the number of turns of 9, 40.

Further, only one set of the primary side bobbin 34 and the secondary side bobbin 35 is integrally formed on the body 31 of the coil bobbin 26, but the number of both bobbins 34, 35 is further increased to alternately form a plurality of sets. Good. In addition, the primary side bobbin 34, the secondary side bobbin 35, and the mounting portion 36 are formed separately from each other without being integrally molded on the body 31, and then the bobbins 34, 35 are sandwiched so as to sandwich the mounting portion 36. The coil bobbin 26 may be obtained by joining and fixing. further,
In that case, as the joining and fixing means, in addition to adhesive fixing with an adhesive, it is also possible to adopt a fitting and locking structure including a locking claw and a locking recess at each bonding site. In this case, the coil bobbin 26 can be disassembled and assembled.

Next, among the technical ideas grasped from the above-mentioned respective embodiments and modified embodiments, technical ideas other than those described in the claims will be described together with their operational effects. (B) A coil bobbin for a transformer in which a primary bobbin and a secondary bobbin sandwiching a mounting portion of a leaky core are integrated so that a plurality of sets are continuous in the direction in which the magnetic fluxes of both coils interlink. This makes it possible to apply it to a transformer having a plurality of primary coils and a plurality of secondary coils. (B) A coil bobbin for a transformer in which the primary side bobbin, the secondary side bobbin, and the mounting portion of the leaky iron core that are separately configured are detachably connected with the mounting portion sandwiched therebetween. In this way, if any of the bobbins is damaged, the coil bobbin can be disassembled and the damaged bobbin can be replaced and changed. (C) A holder provided with a pair of fitting frames capable of fitting and locking the I-shaped leaky iron cores, and fitted in the coil bobbin mounting portion with the I-shaped leaky iron cores fitted and locked in both fitting frames. By using this holder, the I-shaped leaky core can be handled in the same manner as the U-shaped leaky core. (D) A bushing provided with a positioning projection that abuts and engages with the edge of the opening of the main body case, and a locking claw that elastically locks the locking recess on the outer surface of the main body case. According to this bushing,
The amount of insertion into the opening can be easily determined by the positioning protrusion, and the bushing can be temporarily fixed to the opening before the bolt is tightened by the locking claw.

[0046]

According to the first aspect of the present invention, since the mutual position of the primary side coil and the secondary side coil does not fluctuate, it is possible to reliably prevent the occurrence of variations in the output characteristics due to the mutual inductance fluctuations of both coils. it can.

According to the second aspect of the present invention, since the primary coil and the secondary coil are not displaced with respect to the leakage iron core, it is possible to reliably prevent the occurrence of the variation in the output characteristics due to the positional variation of the leakage flux passage. can do.

According to the third aspect of the present invention, since the leakage iron core is not displaced with respect to the primary side coil and the secondary side coil, it is possible to reliably generate the variation in the output characteristics due to the position variation of the leakage magnetic flux passage. Can be prevented.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a first embodiment in which the present invention is embodied in a coil bobbin of a neon transformer.

FIG. 2 is likewise a side sectional view thereof.

FIG. 3 is an explanatory view showing a structure for inserting and fixing a bushing and a mounting bracket to a main body case.

FIG. 4 is a perspective view of a coil bobbin according to the first embodiment.

FIG. 5 is a plan view of the same.

FIG. 6 is an explanatory view showing a method of mounting the I-shaped leaky iron core on the notch.

FIG. 7 is likewise an explanatory view showing a method of mounting the U-shaped leaky iron core.

FIG. 8 is a plan view of a coil bobbin according to a second embodiment.

FIG. 9 is likewise an explanatory view showing a method of attaching the U-shaped leaky iron core to the pocket portion.

FIG. 10 is a plan view of a coil bobbin according to a third embodiment.

FIG. 11 is an explanatory view of a holder in which an I-shaped leaked iron core is fitted and held.

FIG. 12 is also an explanatory view of a holder in which an I-shaped leaky iron core is fitted and held.

FIG. 13 is a plan sectional view showing a conventional technique.

[Explanation of symbols]

26 coil bobbin, 27 primary side coil, 28 secondary side coil, 30 I type leaky core, 34 primary side bobbin,
35 secondary side bobbin, 36 mounting part, 37 notch part as positioning means, 41 U-shaped leakage core, 44 pocket part as positioning means, 45 positioning step part as positioning means.

Claims (3)

[Claims] 1. A coil bobbin for a transformer in which a bobbin of a primary coil and a bobbin of a secondary coil are integrated at a predetermined distance in a direction in which magnetic fluxes of both coils cross each other. 2. A transformer in which the bobbin of the primary coil and the bobbin of the secondary coil are integrated at a predetermined distance in the direction in which the magnetic flux of both coils interlinks, and a mounting portion for the leakage iron core is formed between both bobbins. Dexterous coil bobbin. 3. The bobbin of the primary side coil and the bobbin of the secondary side coil are integrated at a predetermined distance in the direction in which the magnetic fluxes of both coils cross each other, and a mounting portion for the leakage iron core is formed between both bobbins. A coil bobbin for a transformer, wherein the mounting portion is provided with positioning means for immovably attaching the leaky iron core.