JP2003243236A - High-voltage transformer and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-voltage transformer and its manufacturing method, wherein a time required for curing an insulating resin can be shortened so as to improve the transformer in productivity, and a case material can be dispensed with so as to reduce the cost of the transformer. <P>SOLUTION: This high-voltage transformer is equipped with a primary coil and a secondary coil, and the primary coil and the secondary coil are impregnated with an impregnating resin and formed into a coil unit by curing the impregnating resin. The coil unit is formed into a prescribed shape by the use of molding resin for the formation of the high-voltage transformer. Its manufacturing method is provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high voltage transformer such as an ignition coil and a flyback transformer and a method for manufacturing the same.

[0002]

2. Description of the Related Art For example, in an automobile or the like, an ignition coil is used to supply a high voltage to an ignition plug, and a cathode ray tube of a television receiver, a computer monitor or the like applies a high voltage to an anode portion. A flyback transformer is used to do this.

In such a transformer that generates a high voltage, it is important and indispensable to ensure insulation. Therefore, the primary coil and the secondary coil are wound around the outer circumference of the iron core and housed in a case. The casting resin is injected and cured in this case. When injecting the casting resin, a method of injecting in a vacuum is adopted so that the coil is sufficiently filled without generating voids or bubbles. This is because if there are even a small amount of voids or if air bubbles remain in the resin, the insulation properties will deteriorate.

[0004]

However, in the method of injecting and curing the casting resin in the case as described above, since the amount of the resin to be injected and cured is large, the curing speed must be slowed, There is a problem that it takes a long time (generally, about several hours) to cure. This is because if the curing speed is high, when the amount of resin is large, distortion may occur due to curing heat generation, insufficient removal of bubbles, and further, inconvenience such as sink marks may occur. is there. There is also a problem that a case material is required, which leads to an increase in cost.

The present invention has been made in order to address the above-mentioned problems of the prior art, and can shorten the curing time of the insulating resin, thereby improving the productivity and the case material. It is an object of the present invention to provide a high-voltage transformer and a method for manufacturing the same that can reduce the cost by eliminating the above.

[0006]

In order to achieve the above object, a high voltage transformer of the present invention comprises a primary coil and a secondary coil, and these primary coil and secondary coil are impregnated with an impregnating resin. It is characterized in that the hardened coil portion is molded into a predetermined shape with a molding resin.

Here, the impregnating resin may be a solventless thermosetting resin, and the molding resin may be an unsaturated polyester resin or an epoxy resin.
Examples of the high voltage transformer include an ignition coil and a flyback transformer.

In the method of manufacturing a high voltage transformer according to the present invention, the entire coil portion including the primary coil and the secondary coil is impregnated with the impregnating resin, the impregnating resin is cured, and then the coil portion is molded. It is characterized in that the resin for molding is molded into a predetermined shape.

The high voltage transformer manufacturing method of the present invention is formed by applying the impregnating resin to the primary coil winding and the secondary coil winding, winding the coil in a coil shape, and curing the impregnating resin. It is characterized in that a coil portion having the primary coil and the secondary coil thus formed is molded into a predetermined shape with a molding resin.

According to the present invention, the primary coil and the secondary coil are impregnated with the impregnating resin and hardened, and the entire coil portion provided with such primary coil and secondary coil is defined by the molding resin. Since it is molded in the shape of, the curing time of the resin can be greatly shortened and productivity can be improved compared to the conventional high voltage transformer in which the casting resin is injected and cured in the case. Becomes
Moreover, since the insulating property is sufficiently secured by the impregnating resin and the molding resin, the reliability is excellent. Further, since the case can be eliminated, the cost can be reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a sectional view schematically showing an ignition coil according to a first embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a core 11 made of ferrite or the like whose surface is coated with a heat-resistant resin, a primary coil 12 made of polyurethane enamel wire or the like wrapped around the outer periphery thereof, and fitted on the outer periphery thereof. 1 shows a coil portion including a coil bobbin 13 that is formed and a secondary coil 14 that is wound around the coil bobbin 13 and that includes a polyurethane enameled wire or the like. In the present embodiment, the entire coil portion 10 is impregnated with the impregnating resin 20, and the impregnating resin 20 thus impregnated is cured by heating. And these are the molding resin 30
Is molded into a predetermined shape. In addition,
FIG. 2 shows a coil bobbin 13 in which a secondary coil 14 is formed.
It is an enlarged view of a part of.

The impregnation resin 20 is impregnated with the impregnation resin 20 and the heat curing treatment is performed. The impregnation resin 20 is placed in a vacuum chamber containing the impregnation resin 20 and decompressed to about 0.1 to 0.3 kPa. Completely impregnated with the resin for impregnation 20 and then the resin impregnated in the heating tank is cured by heating. The impregnation time is usually about 1 to 5 minutes.

As the impregnating resin 20, a known resin can be used, but it is preferable to use a solventless thermosetting resin from the viewpoints of insulation, curability, environmental consideration, and the like. Above all, it is preferable to use an unsaturated polyester resin or an epoxy resin.

Examples of unsaturated polyester resins include TVB2191K and TVB2906 (both of which are trade names) manufactured by Toshiba Chemical Corporation. As the epoxy resin, a liquid or low-viscosity epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether of polycarboxylic acid, or epoxidation product of cyclohexane derivative can be used. Liquid acid anhydrides such as acid anhydrides, methyltetrahydrophthalic anhydride, phthalic anhydride type derivatives, and methyl nadic acid anhydride, and those containing various liquid curing agents such as amine curing agents are available. Can be mentioned.
It is also possible to use a liquid monoepoxy resin as a concomitant component.

Insulating inorganic fillers such as silica, talc, aluminum hydroxide and calcium carbonate may be blended with these impregnating resins. By using the one in which such an inorganic filler is blended, heat resistance and insulating property can be improved. However, if the content is too large, or if an inorganic filler having a large particle size is blended, the impregnation may be insufficient, so an inorganic filler having a small particle size is preferable, Further, its content is preferably 30% or less of the whole.

In the ignition coil of this embodiment, the coil portion 10 which has been subjected to the above-mentioned treatment is set in a molding die together with other components necessary for the ignition coil, and then the molding resin 30 is molded. It is manufactured by press-fitting and heat-molding.

As the molding method, any of injection molding, transfer molding and compression molding can be applied. Therefore, the molding resin 30 can be used without particular limitation as long as it can be molded, but from the viewpoint of heat resistance, insulating property, moldability, etc., it is an unsaturated polyester resin or epoxy resin. It is preferable to use a resin. Specifically, as the unsaturated polyester-based resin, TAP214, AP401 manufactured by Toshiba Chemical Co., which can be used in any of injection molding, transfer molding, and compression molding methods.
(These are all trade names). Examples of the epoxy resin include KE4200 and KE1006 manufactured by Toshiba Chemical Co. for injection molding, and KE300 series manufactured by Toshiba Chemical Co. for transfer molding (all of which are trade names).

Insulating inorganic fillers such as silica, talc, aluminum hydroxide and calcium carbonate may be blended with these molding resins. By using the one in which such an inorganic filler is blended, heat resistance and insulating property can be improved. The content of the inorganic filler is preferably 50 to 90% of the whole.

In this embodiment, the coil portion 10 is impregnated with the impregnating resin 20, heated to cure the impregnating resin 20, and the molding resin 30 is molded into a predetermined shape. As compared with the conventional ignition coil in which the casting resin is injected and cured in the case, the curing time of the resin is significantly shortened, and efficient production is possible. Moreover, the impregnating resin 20 and the molding resin 30 ensure the insulation properties comparable to those of the conventional ignition coil. Further, since the case is unnecessary, the cost can be reduced.

Next, a second embodiment of the present invention will be described with a focus on differences from the first embodiment. FIG. 3 is a sectional view schematically showing an ignition coil according to the second embodiment of the present invention.

As shown in FIG. 3, in this embodiment, as shown in FIG.
In the ignition coil shown in (1), only the primary coil 12 and the secondary coil 14 are impregnated with the impregnating resin 20.

Such an ignition coil is manufactured as follows, for example. The impregnating resin 20 is attached to the surface of the primary coil winding of a polyurethane enameled wire or the like by passing it through a dipping tank containing the impregnating resin 20, and is wound around the core 11. Similarly 2
The impregnating resin 20 is attached to the surface of the coil winding for the next coil, and this is wound around the coil bobbin 13. After that, the resin 20 is immediately transferred to a heating tank and the impregnated resin 20 is cured by heating.
Then, the coil bobbin 13 is fitted around the core 11,
Similar to the case of the first embodiment, it is set in a mold for molding together with other constituent members required for the ignition coil, and the molding resin 30 is press-fitted into the mold for molding.

Even in such an ignition coil, the curing time of the impregnating resin 20 and the molding resin 30 is significantly shortened as compared with the conventional ignition coil in which the casting resin is injected into the case and cured. Efficient production is possible. In addition, the impregnating resin 20 and the molding resin 30 ensure high insulation. Further, since the case is unnecessary, the cost can be reduced. In addition, in the present embodiment, the impregnation step using the vacuum chamber in the first embodiment is unnecessary, and it is possible to achieve further efficiency improvement and cost reduction.

Although the embodiments described above are examples in which the present invention is applied to the ignition coil, the present invention is not limited to such an example, and a high insulation such as a flyback transformer is provided. It can be widely applied to various high-voltage transformers that require high performance. Also, the ignition coil is not limited to the one having the above structure.

[0026]

EXAMPLES Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

Example 1 A polyurethane enamel wire having an outer diameter of 0.03 mm was wound around a core made of ferrite coated with polyphenylene oxide (PPO) to form a primary coil. A coil bobbin made of polybutylene terephthalate (PBT) was wound with a polyurethane enamel wire having an outer diameter of 0.03 mm to form a secondary coil, and the secondary coil was fitted around the primary coil to form a coil portion.

On the other hand, 100 parts by weight of bisphenol A diglycidyl ether and 9 parts of methyltetrahydrophthalic anhydride
The impregnating resin prepared by stirring and mixing 0 part by weight and 0.5 part by weight of benzyldimethylamine was placed in a vacuum chamber and kept at 40 ° C., and then the pressure in the vacuum chamber was reduced to 0.1 to 0.3 kPa.

After dipping the coil portion preheated to 100 ° C. in the impregnating resin in the vacuum tank for 3 minutes, the coil portion was transferred to a heating tank, and 120
The impregnating resin was cured by heating at 30 ° C. for 30 minutes. Then
After setting this in the injection mold together with other components and raising the mold temperature to 130 ° C, the unsaturated polyester resin (Toshiba Chemical Co., trade name AP214) is placed in the mold. Pressed in. After 2 minutes, the mold was opened, the cured product was taken out, and then finish processing was performed to obtain an ignition coil.

Example 2 A core made of ferrite coated with polyphenylene oxide (PPO) was passed through an immersion tank containing the same impregnating resin as in Example 1 to pass the impregnating resin on the surface. A primary coil was formed by winding a polyurethane enameled wire having a diameter of 0.03 mm. A secondary coil was formed on a coil bobbin made of PBT by winding a polyurethane enameled wire having an outer diameter of 0.03 mm and having an impregnating resin adhered to the surface in the same manner. Immediately after the primary coil and the secondary coil were formed, they were transferred to a heating tank and heated at 120 ° C. for 30 minutes to cure the impregnating resin.

Next, the coil bobbin having the secondary coil was fitted into the outer circumference of the core having the primary coil and set in the injection molding die together with other components. After raising the mold temperature to 130 ℃, unsaturated polyester resin (trade name AP manufactured by Toshiba Chemical Co., Ltd.
214) was pressed into the mold. After 2 minutes, the mold was opened, the cured product was taken out, and then finish processing was performed to obtain an ignition coil.

COMPARATIVE EXAMPLE The coil portion produced in the same manner as in Example 1 was set in a case made of polyphenylene oxide (PPO),
It was preheated to 120 ° C and housed in a vacuum chamber. Then, the pressure inside the vacuum chamber was reduced to 0.1 to 0.3 kPa, and then the casting resin preheated to 60 ° C. was injected into the case over 1 minute. The casting resin includes 100 parts by weight of bisphenol A diglycidyl ether, 90 parts by weight of methyl tetrahydrophthalic anhydride,
What was prepared by stirring and mixing 0.5 part by weight of benzyldimethylamine and 200 parts of crystalline silica (Crystallite A-1 manufactured by Tatsumori Co., Ltd.) was used. After injecting the casting resin, the casting resin was transferred to a heating tank and heated at 90 ° C. for 3 hours and then at 130 ° C. for 2 hours to cure the casting resin. Got The ignition coils obtained in Examples 1 and 2 and Comparative Example all had good insulation characteristics.

[0033]

As described above, according to the present invention, since the curing time of the insulating resin is shortened, the productivity can be improved, and the case material is not required, so that the cost can be reduced. It is possible to obtain a high-voltage transformer capable of achieving the above.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an ignition coil according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of the ignition coil shown in FIG.

FIG. 3 is a sectional view schematically showing an ignition coil according to a second embodiment of the present invention.

[Explanation of symbols]

10 ... coil 11 ... core 12 ... primary coil 13 ... coil bobbin 14 ... secondary coil 20
...... Impregnating resin 30 …… Molding resin

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akihisa Takeuchi             9-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Toshiba             Chemical Co., Ltd. Kawasaki factory F-term (reference) 5E044 AB01 AC01 AD02                 5E070 AA13 AB08

Claims (6)

[Claims] 1. A coil portion comprising a primary coil and a secondary coil, wherein the primary coil and the secondary coil are impregnated with an impregnating resin and cured, and molded into a predetermined shape with a molding resin. A high-voltage transformer characterized by that. 2. The high-voltage transformer according to claim 1, wherein the impregnating resin is a solventless thermosetting resin. 3. The high-voltage transformer according to claim 1, wherein the molding resin is an unsaturated polyester resin or an epoxy resin. 4. The high voltage transformer according to claim 1, wherein the high voltage transformer is an ignition coil or a flyback transformer. 5. The entire coil portion including the primary coil and the secondary coil is impregnated with an impregnating resin, the impregnating resin is cured, and then the coil portion is molded into a predetermined shape with a molding resin. A method for manufacturing a high-voltage transformer, which comprises molding. 6. A primary coil and a secondary coil formed by winding the primary coil winding and the secondary coil winding in a coil shape while applying an impregnating resin and curing the impregnating resin.
A method of manufacturing a high-voltage transformer, comprising molding a coil portion having a secondary coil into a predetermined shape with a molding resin.