JPH09120924A - Manufacture of coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent additives from restraining the impregnation of insulating resin when insulating resin containing addtives is put in a case and the coils are impregnated with the insulating resin. SOLUTION: An ignition coil 11 is fixed on a rotating table 25 of a filling device 22 so that the axis C1 of a secondary bobbin 15 may be aligned with the axis C2 of a drive shaft 24a. A vacuum is produced in a vacuum chamber 23. A filler mainly made of epoxy resin is injected into a space 13 through an injection tube 30. At the same time, the rotating table 25 is rotated by a drive motor 24. Since glass fibers in the filler have a specific gravity greater than that of the epoxy resin, they separate from the secondary bobbin 15 and move near the inside of the case 12. Then the pressure in the vacuum chamber 23 is increased to the atmospheric pressure and a secondary winding 21 is impregnated with the filler in its inside. Since the glass fibers have moved near the inside of the case 12, they do not restrain the impregnation of the filler into the secondary winding 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil manufacturing method, and more particularly to a method of filling a case with a coil body with a filler.

[0002]

2. Description of the Related Art Conventionally, in the case of a coil such as an ignition coil, by filling an insulating resin in the case of the coil and hardening it, parts such as a bobbin and an igniter around which a winding is wound are fixed in the case. , Ensuring insulation between each part. When the insulating resin is filled in the case, first, the coil case is placed in a vacuum container in a vacuum state, and a liquid insulating resin is injected into the case. Next, by raising the internal pressure of the vacuum container to atmospheric pressure, the insulating resin is permeated between the windings wound around the bobbin so that the space between the windings is filled with the insulating resin. There is. In this way, the insulation between the windings is secured by filling the space between the windings with insulating resin.

[0003]

A technique for adding an additive such as glass fiber to the insulating resin is known (for example, Japanese Utility Model Laid-Open No. 4-77220). As described above, the heat resistance and the rigidity can be improved by adding the additive to the insulating resin, and the insulating resin can be made more suitable as the filler.

However, when the insulating resin containing the additive is used as the filler, the additive 51 is adsorbed on the surface of the winding 52 as shown in FIG. , Its surface may be covered with the additive 51. Note that FIG. 5 is a cross-sectional view showing the winding wire 52 and the filler 53 wound around the bobbin 50. In this case, the additive 51 prevents the insulating resin 53 from penetrating between the windings 52, and as shown in the figure, forms a void 54 not filled with the insulating resin 53 between the windings 52. Become. In the coil in which such a gap 54 is formed, the winding 52a and the winding 5 that are wound in separate positions are wound.
Since there is a risk of dielectric breakdown due to the potential difference between the coil and 2b, the coil becomes a defective product, and as a result, there is a problem that the yield at the time of manufacturing is reduced.

The present invention has been made in view of the above problems, and an object thereof is to fill an insulating resin containing an additive in a coil case to allow the insulating resin to permeate between windings of a coil. It is to prevent the penetration from being hindered by the additive.

[0006]

In order to solve the above problems, the present invention is directed to filling a case in which a coil body is arranged with a liquid insulating resin and an additive having a specific gravity larger than that of the resin. A method of manufacturing a coil in which a filler is filled, wherein the filler is injected into the case in a low pressure state, and the case is rotated so that the coil main body is substantially a rotation center, and the additive is added to the coil main body. The main point is to move the filler to a position away from and to infiltrate the filler between the windings of the coil body under high pressure.

(Operation) According to the coil manufacturing method of the present invention, in the low pressure state, in the coil case,
A filler containing a liquid insulating resin and an additive is injected.
Then, the case is rotated about a coil main body disposed inside the case as a substantial rotation center. At this time, since the additive contained in the filler has a larger specific gravity than the insulating resin,
It moves to a position separated from the coil body by the action of the centrifugal force accompanying the rotation.

Next, the case and the coil body are placed in a high pressure state, and the filling material on the outer peripheral portion of the coil body in the case is pressurized to the inside of the coil body, that is,
Penetrates between windings. At this time, since the additive in the filler has moved to a position separated from the coil body, it does not hinder the permeation of the filler between the windings.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied as a method for manufacturing an ignition coil constituting an ignition device for a vehicle or the like will be described below with reference to FIGS.

FIG. 2 is a sectional view of the ignition coil 11. The case 12 of the ignition coil 11 is made of synthetic resin, and as shown in the figure, a housing space 13 having an opening on one end side (right end side in the figure) is formed therein. In this accommodation space 13, the primary bobbin 1
4, parts such as the secondary bobbin 15 and the igniter 16 are arranged, and a filling material (not shown) is filled therein. This filler fixes each component and ensures insulation between each component.

In this embodiment, a filler containing an epoxy resin as a main component, which is excellent in insulation and heat resistance and has high mechanical strength, is used. In addition, this filling material
Glass fibers having a higher specific gravity than the epoxy resin (other inorganic substances such as silica particles may be added) are added. In this way, by adding glass fiber,
The heat resistance, crack resistance, and strength of the filler are improved, and the linear expansion coefficient thereof is adjusted to a predetermined value. The weight ratio of both is (epoxy resin):
(Glass fiber) = 3: 7
It is desirable for improving heat resistance, crack resistance, and strength. The epoxy resin constitutes the insulating resin of the present invention, and the glass fiber constitutes an additive.

The primary bobbin 14 is fitted around a core 17 penetrating the inside of the case 12, and a primary winding 18 covered with an insulating film is wound around the core 17. There is. A secondary bobbin 15 is fitted around the outer circumference of the primary bobbin 14. The secondary bobbin 15 has a plurality of winding grooves 19 defined by ribs 20, and the secondary winding 21 has a plurality of winding grooves 19 formed in layers in the winding groove 19 as shown in FIG. It is wound. Secondary winding 21
Like the primary winding 18, it is coated with an insulating coating, and its diameter is smaller than that of the primary winding 18. The coil body of the present invention is configured by the secondary bobbin 15 and the secondary winding 21 wound around the bobbin 15.

Next, a method of filling the case 12 of the ignition coil 11 with a filler will be described. FIG.
Is for explaining the filling method of the filling material in the present embodiment, and shows a schematic configuration of the filling device 22 according to the method.

The filling device 22 includes a vacuum chamber 23,
It is provided with a drive motor 24, a rotary plate 25, and the like. The vacuum chamber 23 is connected to an exhaust pump (not shown) via an exhaust passage, and the inside of the vacuum chamber 23 can be brought to a substantially vacuum state by driving the exhaust pump.

A drive motor 24 is provided in the vacuum chamber 23.
And a disk-shaped rotary plate 25 is connected and fixed to the drive shaft 24a of the motor 24. The rotary plate 25 is rotatable by driving the drive shaft 24a of the drive motor 24. Further, on the upper surface of the rotary plate 25, two fixing jigs 26 having a substantially L shape are formed.
Is arranged and the rotating plate 25 is attached by the bolt 27.
It is fastened and fixed to.

As shown in FIG. 1, the ignition coil 11 is arranged between the fixing jigs 26. The case 12 of the coil 11 is fixed to the fixing jigs 26 when the fixing jigs 26 are tightened and fixed by the bolts 27.
And is fixed on the rotary plate 25. At this time, as shown in FIG. 1, the ignition coil 11 is positioned so that the axial center C ₁ of the secondary bobbin 15 in the longitudinal direction and the axial center C ₂ of the drive shaft 24a substantially coincide with each other. A lid 28 is placed on the case 12 so as to close the opening of the housing space 13. A through hole 29 for injecting the filler into the accommodation space 13 is formed in the lid body 28.

An injection pipe 3 is provided above the vacuum chamber 23.
0 is provided. One end side of the injection pipe 30 is opened corresponding to the through hole 29 of the lid 28, and the filling material can be injected into the accommodation space 13 of the ignition coil 11 through the injection pipe 30 and the through hole 29. Has become.

When the filling material is filled in the accommodation space 13, first, the vacuum chamber 23 is set by the exhaust pump.
The air inside is discharged and the internal pressure is adjusted so that the inside of the chamber 23 is in a substantially vacuum state. At this time, the vacuum chamber 2
In order to make the air in the chamber 3 as lean as possible, the same chamber 2
It is desirable to adjust the internal pressure of 3 to be 3.0 Torr or less.

When the internal pressure of the vacuum chamber 23 is adjusted,
In the accommodation space 13, the injection tube 30 and the through hole 29.
A predetermined amount of filler is injected through the. The filling material has a predetermined viscosity by being temperature-controlled, and is filled so as to cover the primary bobbin 14, the secondary bobbin 15, the igniter 16 and other parts in the storage space without any gaps. Here, since the secondary winding 21 has an extremely small diameter,
The filling material does not sufficiently penetrate between the secondary windings 21,
The filler penetrates only into a part between the windings 21 on the surface side (the upper side in FIG. 4) of the windings 21.

Next, the rotary plate 25 is rotationally driven by the drive motor 24 to rotate the case 12 of the ignition coil 11. At this time, since the glass fibers contained in the filler injected into the accommodation space 13 have a larger specific gravity than the epoxy resin, they are subjected to a larger centrifugal force than the epoxy resin per unit weight.

FIG. 3 is for explaining the state of the glass fiber when it is subjected to centrifugal force. It is arranged in the accommodation space 13 of the case 12 and the secondary winding 21 is wound. Two
Next bobbin 15 and filler A injected into the same space 13
(Epoxy resin R and glass fiber S).
As shown in the figure, the glass fiber S receives the centrifugal force larger than that of the epoxy resin R and moves away from the secondary bobbin 15 to the inner peripheral wall side of the case 12. That is, the glass fibers S (indicated by black dots in the figure) are non-uniformly dispersed in the accommodation space 13, and the distribution density of the glass fibers S becomes small around the secondary bobbin 15, and conversely,
The distribution density near the peripheral wall of the case 12 becomes large.

Next, the rotary plate 2 is driven by the drive motor 24.
In the state where 5 is kept rotating, the atmosphere is introduced into the vacuum chamber 23 from the exhaust pump through the exhaust passage, and the internal pressure of the chamber 23 is raised to the atmospheric pressure. Thus, when the pressure in the vacuum chamber 23 is increased, the pressure on the surface side (the upper side in FIG. 4, the outer peripheral side in FIG. 1) of the secondary winding 21 becomes the inner side (the lower side in FIG. 4). Temporarily greater than pressure. Therefore, the filling material in the vicinity of the surface of the secondary winding 21 moves to the inside due to the pressure difference, so that each winding 21
Infiltrate between. As a result, no gap is formed between the secondary windings 21 and the secondary windings 21 are filled with the filling material.

At this time, since the distribution density of the glass fibers around the secondary bobbin 15 is small as described above, the glass fibers are adsorbed on the surface of the secondary winding 21 and hinder the permeation of the filler. The filling material quickly penetrates into the inner side of the secondary winding 21.

After the filler has sufficiently penetrated to the inside of the secondary winding 21 as described above, the rotation driving of the drive motor 24 is stopped and the ignition coil 11 is taken out of the vacuum chamber 23. Then, the ignition coil 11 is heated to a constant temperature for a predetermined time. In this step, the glass fibers that are non-uniformly distributed in the accommodation space 13 are dispersed with the passage of time and are changed into a uniform distribution state again. Further, by being heated to a constant temperature, the epoxy resin-containing filler exhibits thermosetting properties, and the curing causes each component in the accommodation space 13 to be fixed.

By the above steps, the filling space is filled with the filling material. Since glass fiber is added as an additive to this filler to improve heat resistance, crack resistance, and strength, the ignition coil 11 repeatedly changes in temperature depending on the use environment and undergoes thermal expansion. Even in this case, the filler will not be damaged. Furthermore, since the linear expansion coefficient is adjusted, thermal expansion of the filler does not cause excessive thermal stress on the case 12.

Since the filler that has penetrated into the inner side of the secondary winding 21 contains almost no glass fibers, there is concern that the rigidity of the filler may be reduced. However, since each wire of the secondary winding 21 has substantially the same effect as that of glass fiber, there is no possibility of causing such rigidity reduction.

When the pressure is reduced to a vacuum state, the accommodation space 1
Some air may remain inside the third or secondary winding 21, but this air contracts to a negligible amount when the pressure inside the vacuum chamber 23 is increased to atmospheric pressure. Therefore,
Bubbles of a size that causes dielectric breakdown do not occur in the accommodation space 13, particularly in the secondary winding 21.

The present embodiment described above can bring about the following effects. (A) When the filler penetrates into the inner side of the secondary winding 21,
The penetration can be prevented from being hindered by the glass fiber contained in the filler. Therefore, 2 fillers
It can penetrate to the inner side of the next winding 21,
Predetermined insulation between the windings 21 can be ensured.

(B) In the present embodiment, the glass fiber is separated from the periphery of the secondary winding 21 by utilizing the difference in the magnitude of the centrifugal force acting on the epoxy resin contained in the filler and the glass fiber. Moved to the position. Therefore, the effect shown in the above (a) can be achieved by extremely simple equipment.

(C) In the present embodiment, when the filler is infiltrated into the inner side of the secondary winding 21, the pressure difference generated between the surface side and the inner side of the secondary winding 21 is utilized as described above. ing. In the present embodiment, this pressure difference is reduced to the vacuum chamber 23.
Since it is generated by a process in which the vacuum pressure is released and then the atmospheric pressure is released, the pressure control can be facilitated.

(D) In the present embodiment, since the filler can penetrate into the inner side of the secondary winding 21 without being hindered by the glass fiber, the degree of freedom in design can be increased. . That is, in the past, a small-diameter winding is wound densely, or the winding height H
The design change that increases (shown in FIG. 4) is limited because it makes penetration of the filler material more difficult, but in the present embodiment, the secondary winding 21 has a smaller diameter. It is possible to select a suitable winding, and the winding 21 can be wound in a denser state. In addition, the winding height H can be increased.

Further, by winding the small-diameter winding in a dense state and increasing the winding height H, the ignition coil 11 can be miniaturized.

(E) In the present embodiment, the glass fiber is prevented from being adsorbed on the surface of the secondary winding 21 so that the filler is sufficiently permeated into the inner side of the secondary winding 21. I chose When the glass fiber is adsorbed on the surface of the secondary winding 21, the penetration of the filler is hindered and the distribution density of the glass fiber contained in the filler in the other part of the accommodation space 13 is reduced. However, in the present embodiment, such a problem can be solved at the same time.

The present embodiment can be carried out as follows. (1) In the present embodiment, epoxy resin is selected as the insulating resin contained in the filler and glass fiber is selected as the additive added to the insulating resin. However, the insulating resin and the additive are limited to this combination. Not something. That is, the specific gravities of the insulating resin and the additive (γ _r and γ _a , respectively)
As long as satisfies the relation of (γ _r <γ _a ), any one can be selected as the insulating resin and the additive, and for example, crystalline silica or the like can be selected as the additive. Further, in the present embodiment, the weight ratio of the epoxy resin and the glass fiber is set to (3: 7), but this weight ratio may be changed to appropriately change the mechanical properties, viscosity, etc. of the filler. Good.

(2) In this embodiment, the vacuum chamber 2
The internal pressure of 3 is increased to atmospheric pressure, and the filling material is used for the secondary winding 2
Although the rotation of the rotary plate 25 was stopped after permeating the inside of the rotary plate 25, the internal pressure of the vacuum chamber 23 was increased to the atmospheric pressure after the rotation of the rotary plate 25 was stopped, and the secondary filling material was added. You may change a process so that it may permeate into the inside of the winding wire 21.

In this case, when the rotation of the rotary plate 25 is stopped, the glass fibers that are non-uniformly distributed in the housing space 13 of the case 12 disperse and move, and change to have a uniform distribution. Therefore, when the process is changed as described above, the permeation of the filler into the inner side of the secondary winding 21 is completed at the initial stage when the glass fiber starts the dispersion movement.

(3) In the present embodiment, the coil manufacturing method according to the present invention is applied to the ignition coil 11 manufacturing method. However, the present invention is not limited to the ignition coil 11 and various coils (for example, , Flyback transformer).

The technical idea grasped from the above-described embodiment will be described below together with its effect. (A) In the method for manufacturing a coil according to claim 1,
While injecting the filler into the case in a vacuum state, the case is rotated so that the coil body is substantially the center of rotation to move the additive to a position separated from the coil body, and the coil is kept in an atmospheric pressure state. Infiltrate the filler between the windings of the body.

According to the coil manufacturing method of the above (a), in addition to the operational effects of the coil manufacturing method described in claim 1, it is possible to facilitate pressure control in the manufacturing process.

[0040]

According to the coil manufacturing method of the present invention, when the filler is permeated between the windings of the coil body, it is possible to prevent the permeation from being hindered by the additive contained in the filler. it can. Therefore, a gap is not formed between the windings and the filler is infiltrated, so that a predetermined insulating property between the windings can be secured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an entire filling device according to an embodiment.

FIG. 2 is a cross-sectional view of an ignition coil.

FIG. 3 is an explanatory diagram for explaining an operation in one embodiment.

FIG. 4 is an enlarged cross-sectional view showing a secondary bobbin and a secondary winding.

FIG. 5 is an enlarged cross-sectional view showing a bobbin and a winding wire of an ignition coil manufactured by a conventional technique.

FIG. 6 is an enlarged cross-sectional view showing a winding wire and a filling material of an ignition coil manufactured by a conventional technique.

[Explanation of symbols]

11 ... Ignition coil, 12 ... Case, 15 ... 2
Next bobbin (coil body), 21 ... Secondary winding (coil body), R ... Filler material, R ... Epoxy resin (insulating resin), A
... glass fiber (additive).

Claims (1)

[Claims] 1. A method of manufacturing a coil, comprising filling a filler containing a liquid insulating resin and an additive having a larger specific gravity than the resin in a case in which the coil main body is disposed, the method comprising: While injecting the filler into the case, the case is rotated so that the coil body is substantially the center of rotation to move the additive to a position separated from the coil body, and the coil body is wound in a high pressure state. A method for manufacturing a coil, wherein a filler is impregnated between the wires.