JPH01268096A - Sealing structure of electric equipment and the like - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is applicable to electrical equipment such as solenoids, transformers, semiconductor devices, etc.
This relates to the sealing structure of N-type devices and the like.

(Prior technology) Is a solenoid used as a means of driving the spool? It can be incorporated into the UIL valve or used as an actuator by itself. In order to generally make it waterproof, dustproof, insulated, and easy to install in a predetermined position, the yoke 3 on which the coil bobbin 2 with the coil 1 wound thereon is assembled is sealed with resin, as shown in Figure 1. A casing 4 is formed.

Conventionally, sealing with resin was done by filling the periphery of the yoke 3 with a thermosetting resin and then heating and hardening the resin in order to smoothly dissipate the heat generated in the coil 1 and prevent moisture from entering. I had it fixed at 3.

Furthermore, not only solenoids but also electrical equipment such as transformers and semiconductor elements are sealed with resin for waterproofing, dustproofing, insulation, and the like.

(Problems to be Solved by the Invention) However, in the conventional product, cracks may occur in the resin casing 4 due to the use of the solenoid, resulting in loss of insulation. The reason for this is that a steel plate or a silicon steel plate is used as the M material of the yoke 3 enclosed in the casing 4, and galvanized etc. are applied to prevent rust, but since it is formed by a press etc., there are many notched parts. It is conceivable that stress concentration occurs in the notch portion due to the difference in thermal expansion between the yoke 3 and the casing 4 due to the heat generated by the coil when the solenoid is used, causing cracks to occur in the casing 4. Therefore, it is thought that cracks occurring in the casing 4 can be prevented by using materials with the same coefficient of thermal expansion for the yoke 3 and the casing 4, but with the current technology, the thermal expansion of both materials can be prevented. It is impossible to make the rates the same.

Further, similar problems occur in other electrical devices such as transformers that employ resin sealing structures.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to seal the periphery of metal parts such as yokes with resin.
An object of the present invention is to provide a resin-sealed structure for electrical equipment, etc., which can prevent cracks from occurring during use.

<Means for Solving the Problems> In order to achieve the above object, in the present invention, a film is formed by electrodeposition on the surface of a metal part that undergoes thermal expansion during use, and the metal part is coated with a thermosetting resin. Sealed. As the electrodeposition coating, both anionic electrodeposition coating and cationic electrodeposition coating can be employed, but cationic electrodeposition coating is preferable. Further, as the thermosetting resin for sealing, epoxy resin is preferable from the viewpoints of ease of operation in curing molding, little shrinkage during curing, mechanical strength, electrical insulation, chemical resistance, etc.

(Function) The film formed on the surface of metal parts by electrodeposition has high adhesion to the metal, so even if the yoke as a metal part undergoes thermal expansion due to the heat generated by the coil when using a solenoid, The state of close contact with the yoke surface is maintained. In addition, since the film formed by electrodeposition is a resin, it has a higher affinity with the thermosetting resin used as a sealing material than a conventional metal plating layer. The adhesion between the film and the thermosetting resin used for the sealing material is increased. Therefore, the internal pushing force generated by the difference in coefficient of thermal expansion between the metal parts and the sealing resin due to the heat generated during use of electrical equipment such as solenoids is 1! ! It is absorbed by the entire surface and prevents cracks from forming.

(Examples) The present invention will be explained in more detail below using examples and test examples embodied in solenoids. Coil outer diameter 18.5mm,
An electrodeposition film was formed on the surface of the yoke to which a coil having a coil size of 26 mm was assembled by cationic electrodeposition coating.

The electrodeposition paint used was an ordinary cationic electrodeposition paint whose main resin was an epoxy resin into which amino groups had been introduced, and which contained a blocked isocyanate resin as a curing agent. After assembling the coil to this yoke, it was sealed with epoxy resin in the same manner as before to form a rectangular parallelepiped test specimen I1 as shown in Fig. 2.
．． I made S. In addition, as a comparison sample, a similar sample S was manufactured using a yoke that was not subjected to electrodeposition coating. Then, a temperature cycle test was conducted on these samples under the following conditions, and it was checked whether or not cracks were generated at each cycle.

One cycle is completed by keeping the sample in a constant temperature bath at -25°C for 2 hours, then leaving it at room temperature for 30 minutes, then placing it in a constant temperature bath at 70°C for 2 hours, and then leaving it at room temperature again for 30 minutes. .

For the sample with electrodeposition coating, no cracks were observed even after completing 15 cycles, whereas for the sample without electrodeposition coating, no cracks were observed after 1 cycle.
) and (b), the occurrence of cracks C was observed. In addition, after completing 15 cycles, the sample was checked for wire breakage and insulation, but no abnormalities were found. Furthermore, the thickness of the electrodeposited film on the yoke surface was almost the same as the thickness of conventional anti-corrosion plating, and there was no decrease in magnetic efficiency due to increased magnetic resistance.

Next, a test was conducted to examine the adhesion between the epoxy resin and the electrocoated film. The test method is as shown in Fig. 4, where 'Ffii! A film 6 is formed by painting, a washer 7 is embedded between both metal fittings 5 as a breakage point, and the epoxy resin 8 is cured to prepare a sample for a tensile test.The sample is subjected to a 50-ton tensile test. A tensile test was carried out using a machine at a tensile speed of 5 mm/min, and the breaking strength and the location of the damaged part were investigated. In addition,
Both cationic electrodeposition coating and anionic electrodeposition coating were carried out as electrodeposition coatings, and similar tests were also carried out on comparison samples with galvanized metal fittings 5 and those coated with melamine baking. . The number of samples was three in each case. The test results are shown in the table.

In the case of pivots and 70 zinc plating or melamine baking, in the case of a sample in which a film is formed on the surface of the metal fitting 5 by painting, the interface between the plating part and the resin or the interface between the metal and the film can be easily removed by simply pulling the sample by hand. Peeling occurred. On the other hand, when a film is formed by cationic electrodeposition, the breakage occurs in the epoxy resin part, and its strength corresponds to the calculated value of epoxy resin breakage (notched) strength of 190 Kg/c" Adhesion between paint film and metal and cation 1!
This proves that the adhesion between the painted film and the epoxy resin is extremely strong. In addition, in the case of anionic electrodeposition coating, unlike in the case of cationic electrodeposition, rupture occurs at the interface between the ffi coating and the epoxy resin, and the adhesion between the electrodeposition coating and the epoxy resin is affected by the cationic electrodeposition. Although it is weaker than the case of pre-coating, it is strong enough for practical use.

In addition, in the above embodiment, an example was described in which epoxy resin was used as the sealing resin, but thermosetting resins other than epoxy resin may be used. Further, the present invention may be applied to sealing structures of electrical equipment such as transformers other than solenoids and semiconductor elements.

(Effects of the Invention) As detailed above, according to the present invention, the sealing resin and the electrodeposition coating film adhere to each other due to the action of the electrodeposition coating film formed on the surface of the metal component that undergoes thermal expansion during use. Improved sex,
For example, when using a solenoid to close electrical equipment, the resistance to heat shock due to the heat generated by the coil increases, and the occurrence of cracks, etc. is reliably prevented, and the waterproofing and
Moisture-proofing and insulation properties are improved, and the rust-preventing effect on exposed parts of metal parts is also improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the solenoid sealing structure, Figure 2 is a schematic perspective view of a heat shock test sample, Figure 3 (a),
(b) is a schematic perspective view showing the position of cranks generated in a comparative sample by a heat shock test, and FIG. 4 is a cross-sectional view of a sample for measuring tensile strength. Coil 1, yoke 3, casing 4゜Patent applicant CKD Co., Ltd. Fig. 2 Fig. 4

Claims (1)

[Claims] 1. Sealing of electrical equipment, etc., characterized in that a film is formed by electrodeposition coating on the surface of a metal part (3) that undergoes thermal expansion during use, and the metal part (3) is sealed with a thermosetting resin. Stop structure.