JPH02283009A - Liquid-impregnated enclosed capacitor - Google Patents

Abstract

PURPOSE:To obtain a liquid-impregnated enclosed capacitor which is excellent in sealing property and long in service life by forming coating films of a fluoropolymer on surfaces of components which come into contact with rubber- made sealing members. CONSTITUTION:O-rings 8 and 9 are made of silicone rubber having hardness of 70 and the surfaces of the rings 8 and 9 and those of all components which come into contact with the rings 8 and 9, namely, the flange section 1a of a bolt terminal 1, upper and lower end sections of an insulator 5, and upper surface of an upper lid 7 are coated with fluoropolymer films by applying a solution containing 20-% fluoro-olefin and alkyl vinyl-ether copolymer/ chlorofluorocarbon TF solution to the surfaces and drying the solution for 30 minutes at 105 deg.C. When the fluoropolymer films are formed on the surfaces of the components in such way, oil leakage from the sealed part of this capaci tor can be prevented even when the compressed deformation is lowered than 30%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid-impregnated sealed capacitor impregnated or filled with liquid insulating oil, and particularly relates to an improvement in the sealing performance thereof.

[Prior art] A capacitor is impregnated with liquid insulating oil or exposed to light.
It is used in boat fishing as a means to improve the performance of capacitors. The capacitor container is then sealed to prevent this liquid insulating oil from leaking out. Rubber sealing In, which utilizes the elasticity of rubber, is widely used as such a sealing method.

In the rubber sealing structure, a rubber sealing material is sandwiched between structures and strongly compressed to make them adhere tightly without any gaps, thereby preventing leakage of insulating oil. In this case, if the compression of the rubber sealant is too weak, gaps will be created due to microscopic irregularities between the structure and the rubber sealant, and there is a risk of oil leakage due to capillary action of the liquid. Therefore, when fishing on a boat, the sealing performance is improved by compressing the rubber sealant as strongly as possible and increasing the repulsive force of the rubber sealant.

However, even in capacitors whose sealing performance is improved by strongly compressing the rubber sealing material, oil leakage may occur after a long period of time. If such oil leakage is left untreated, it not only contaminates other parts, but also reduces the amount of liquid in the leaking capacitor itself, leading to a decline in performance. This point will be specifically explained below.

Figure 1 shows terminal 'AM' of an oil-filled film capacitor using a rubber sealing structure.

In FIG. 1, reference numeral 1 denotes a bolt terminal, and a flange portion 1a is provided at the intermediate portion thereof. The upper part of the bolt terminal 1 than the flange part 1a is threaded, and a nut 2, a spring washer 3, and a flat washer 4 are inserted in combination.
The external electrode portion is received by the flange portion 1a. These parts 1-4 are made of copper or copper alloy,
Finished with tin or nickel plating. Further, the portion below the flange portion 1a of the bolt terminal 1 is shaped like a rod without a screw, and is inserted into hollow insulators 5 and 6. These insulators 5 and 6 are attached from above and below to a hole provided in the upper lid 7 of the container, and sandwich the upper lid 7. The rubber sealing structure between the bolt terminal 1 and the insulator 5.6 and the rubber sealing structure between the insulators 5, 6 and the upper M7 include the flange portion 1a of the bolt terminal 1 and the upper end of the upper insulator 5. O-rings 8 and 9 made of silicone rubber are sandwiched between the upper insulator 5 and the upper cover 7 as rubber sealants, respectively. In this state, after aligning the flange portion 1a of the bolt terminal 1 by pressing it against the upper end of the upper insulator 5, place the washer 10 on the lower part of the lower insulator 6, and then It's hardened. As a result, the bolt terminal 1 and the insulators 5, 6 are fixed to the upper M7 of the container, and the O-rings 8, 9 are compressed.

In the rubber sealing structure described above, if the compressive deformation rate of the rubber sealing material is less than 40%, there is a risk of initial sealing failure, and if the compressive deformation rate is 40% or more, sufficient sealing performance is not achieved. Since it can be obtained, it is usually controlled at 40% or more. However, after long-term use, oil leakage may occur as described above. As a result of the inventor's investigation of such oil leaking structures, it was found that the repulsive force of the rubber sealant was reduced. When we roughly investigated the relationship between the compression deformation rate and compression set of rubber sealants, we found that when the compression deformation rate is 40% or more, the compression set becomes extremely large, which leads to a decrease in elasticity over time, and the oil It was found that leakage was more likely to occur.

Therefore, in order to suppress permanent deformation of the rubber sealant, it is desirable to set the compression deformation rate to less than 40%. The gaps caused by oil leakage cannot be filled completely, and oil leaks are likely to occur from the initial stage. In particular, oils with low surface tension,
For example, when alkyldiphenylethane or the like is used as the insulating oil, the oil has strong permeability and is likely to leak.

[Problems to be Solved by the Invention] As explained above, in the rubber sealing structure applied to the conventional liquid-impregnated sealed capacitor, when the compressive force of the rubber sealing material is weakened, the rubber sealing material and the structure become A small gap is created at the boundary of the rubber sealing material, making it easy for oil leakage to occur.
Initially, oil leakage is difficult, but as the rubber sealant becomes susceptible to permanent compression deformation, it becomes impossible to maintain a long service life.

Therefore, in order to avoid such problems, the permissible range of pressure deformation rate of the rubber sealing material must be set extremely narrow, but at this stage it is possible to satisfy both sealing performance and compression set. No such structure has been obtained.

The present invention was proposed in order to solve the problems of the prior art as described above, and its purpose is to solve the problem of oil leakage due to capillary action in the area of low compression deformation rate where compression set is difficult to occur. By realizing a sealed structure that can prevent this, it is possible to provide a liquid-impregnated sealed capacitor with excellent sealing performance and a long life.

[Means for Solving the Problems] The liquid-impregnated closed capacitor according to the present invention has a rubber sealing structure in which a rubber sealing material is sandwiched between the structures as a means for sealing the container, and the rubber sealing material of the structure and It is characterized in that a fluorine-based polymer film is formed on the contacting surface or on both this surface and the surface of the rubber sealant.

In this case, as the fluoropolymer, a fluid solution of a fluoropolymer having a smaller value (usually 11 to 13 dyne/cm) than the surface tension of the liquid S rim impregnated or lost in the capacitor is used. Then, this fluid solution of the fluoropolymer is applied to the surface of the structure that will come into contact with the rubber sealant, and dried at room temperature or by heating to form a film, followed by assembly.

In addition, when fluorine-based rubber is used as a rubber sealant, the surface tension of the rubber itself is small, so no special treatment is required on the surface of the rubber sealant. SBR rubber, CR rubber,
When using EPT rubber, thiocol rubber, 2) ~ Lil rubber, silicone rubber, etc., these rubbers themselves have a high surface tension, so they should be treated with the fluoropolymer container mentioned above in the same way as the contact surface of the structure. , forming a film. After this, it is sandwiched between structures. In this case, the compression ratio of the rubber sealant is suitably about 30%.

[Action] The action of the non-invention having the above structure is as follows. In other words, the surface of the fluorine-based polymer film, which has a small surface tension, repels the liquid insulating oil, which has a larger surface tension. The invention has excellent effects in preventing oil leakage from the peripheral portion. Therefore, according to the present invention, it is possible to realize a sealed structure in a region of low compression deformation rate where compression set is difficult to occur, and which can prevent oil leakage due to capillary phenomenon, and which provides long-life liquid with excellent sealing performance. We can provide impregnated sealed capacitors.

Furthermore, since the fluoropolymer film has excellent chemical and thermal stability, it has the advantage of significantly improving the high-temperature life expectancy of capacitors.

[Example] Examples of the liquid-impregnated sealed capacitor according to the present invention will be described below.

First Embodiment - Fig. 1 First, the present invention is applied to the terminal structure of an oil-filled film capacitor shown in Fig. 1, and this is referred to as a first embodiment. Note that the basic structure of this embodiment is the same as the structure described as the prior art, so the explanation will be omitted, and the features of this embodiment will be mainly explained below.

That is, the O-rings 8 and 9 shown in FIG. A 20% fluoroolefin and alkyl vinyl ether copolymer/Freon TF solution is applied to the surfaces in contact with the O-ring 8.9 at the flange portion 1a, the upper and lower ends of the insulator 5, and the upper surface of the upper lid 7, respectively. 105
A fluoropolymer film was formed by drying at ℃ for 30 minutes. After this, each part is assembled for the first time,
The structure shown in Figure 1 has been completed. In addition, in this example,
By adjusting the lower end portion of the bolt terminal 1, the compressive deformation rate of the O-rings 8 and 9 was set to 25 to 30%.

A capacitor was manufactured using the terminal structure configured as described above. In this case, alkyldiphenylethane, which is a low viscosity insulating oil, was impregnated as the liquid insulating oil.

When we conducted an airtight test on this capacitor by heating it at 85°C for 3 hours, there was no oil leakage.
It withstood a durability test of 15,000 hours at 0'C without any abnormality.

The reason for this is that O-rings 8 and 9 are necessary for rubber sealants.
By forming a fluoropolymer film on the surface of the O-rings 8 and 9 and on the surface of the structure that contacts them, leakage from the sealing part can be prevented even if the compressive deformation rate of the O-rings 8 and 9 is as low as 30% or less. In addition, since the compression set is low, the compression set can be kept to a minimum, which is thought to have ensured durability.

2 and 3 show the relationship between the compression deformation rate and extraction leakage of the O-rings 8 and 9, and the relationship between the pressure Wi deformation rate and compression set. In this case, as mentioned above, O-ring 8
, 9 is a silicone rubber with a hardness of 70, and the curve B is a curve showing the characteristics of the capacitor of the alkyldiphenylethane present example.
is a curve showing the characteristics of a conventional capacitor in which a fluoropolymer film is not formed on the sealing part. From this figure 2, in conventional example B, the compression deformation rate is 40%.
If it is less than 10%, the initial seal failure rate increases rapidly, whereas in Example A, there is no initial seal failure occurrence even when the rate decreases to 20%, and there is only a slight increase in the initial seal failure rate at around 10%. It can be seen that a product is sold just by the occurrence of defective products. That is, from FIG. 2, even if the compressive deformation rate of the O-rings 8 and 9 is set much lower than the conventional one in this embodiment A, no initial sealing failure occurs and the sealing performance is excellent. It is clear that

FIG. 4 shows comparative data regarding changes in insulation resistance in a humidity load test between the capacitor according to this example and a conventional capacitor in which a fluoropolymer film is not formed on the sealing portion. Here, the test conditions are a temperature of 40
'C, relative humidity 90-95%, 1000WVX1.25
It is necessary to double the voltage.

In addition, the sample capacitor in both this example and the conventional example is 10
00WV. AC, 4! l F17) N t-11/Te7 satay. It is clear from FIG. 4 that while the insulation resistance of the conventional capacitor is unstable, the insulation resistance of the capacitor of this embodiment is extremely stable.

■Other embodiments...Figs. 5 to 9 In the embodiments shown in Figs. 5 to 7, silicone rubber is used as the rubber sealing material, and the surface of the rubber sealing material and the surface of the rubber sealing material are The same fluoropolymer film as in Example 1 was applied to the surface of the skin structure that came into contact with it.

The embodiment shown in FIG.
An O-ring 12 made of silicone rubber is provided between A and M7 of the container. The other structure is the same as that of the first embodiment, and an O-ring 8 is provided between the flange portion 1a of the bolt terminal 1 and the upper end portion of the insulator 11. Even in such a configuration, the effect of the sealing part is the same as in the first embodiment.

The embodiment shown in FIG. 6 is a modification of the embodiment shown in FIG. 5, in which a hexagonal nut 13 is used instead of providing the flange portion 1a on the bolt terminal 1.

The other configurations are the same as the embodiment 191 in FIG. 5, and the effects are also the same.

The embodiment shown in FIG. 7 is a modification of the first embodiment in which a hexagonal nut 14 is used in the lower tightening structure, but the sealing structure is the same as in the first embodiment and has the same effect. can get.

In the embodiment shown in FIG.
is inserted into the insulator 16, and a silicone rubber 17 is installed between the shaft of the rivet 15, the case M7, and the insulator 16. In this case, the sealability of the contact surface between the insulator 16 and the silicone rubber 17 is not important, but the contact surface between the silicone rubber 17 and the shaft of the rivet 15 and the contact surface between the silicone rubber 17 and the top lid 7 of the case are important. Since this is a sealed portion, if a fluoropolymer film is formed on this portion, the same effects as in each of the above embodiments can be obtained.

The embodiment shown in FIG. 9 is a modification of FIG. 8, in which a bolt 18 and a nut 19 are used in place of the rivet 15, and the effects are essentially the same.

It should be noted that the present invention is not limited to the above-mentioned examples, and as the fluorine-based polymer, it is also possible to use polyvinylidene fluoride and copolymers with a low degree of fluorination, and as the solvent, , dimethyl acetamide, dimethyl phthalate, diisobutyl ketone, and mixtures thereof may be used in addition to the above-mentioned examples, and after applying these organosols or dispersion paints to the relevant areas,
Similar effects can be obtained by heating at ~400'C to form a fluoropolymer film.

[Effects of the Invention] As explained above, the present invention provides a capacitor having a rubber sealing structure in which fluorine is added to the surface of the structure that comes into contact with the rubber sealant, or to both this surface and the surface of the rubber sealant. By forming a polymer film, it is in the region of low compression deformation rate where compression set is difficult to occur, and it is also possible to prevent oil leakage due to capillary phenomenon, so it is a long-life liquid with excellent sealing performance compared to conventional products. We can provide impregnated sealed capacitors.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a general bolt terminal structure, and is also a sectional view showing a first embodiment to which a liquid-impregnated sealed capacitor of the present invention is applied. Fig. 2 is a graph showing the relationship between the compression deformation rate and oil leakage of the O-ring in the first embodiment, Fig. 3 is a graph showing the relationship between the compression deformation rate and compression set, and Fig. 4 is a graph showing the relationship between the O-ring compression deformation rate and compression set in the first embodiment. 7 is a graph showing comparative data regarding changes in insulation resistance in a humidity load test between a capacitor according to an example and a capacitor of a conventional example. Figures 5 to 9 are cross-sectional views showing embodiments of the stomach according to the present invention. 1... Bolt terminal, 1a... Flange part, 2...
Nut, 3...Spring washer, 4...Flat washer 5°6...Insulator, 7...Top lid, 8,9...
・O-ring, 10... washer, 11... insulator, 11a... flange part, 12... O-ring,
13.14...Hexagon nut, 15...Rivet, 1
6... Insulator, 17... Silicone rubber, 18.
...Boruto, 19...Natsuto.

Claims (4)

[Claims] (1) It is impregnated or filled with liquid insulating oil, and a rubber sealing material is sandwiched between the structures as a means of sealing the container.
A liquid-impregnated sealed capacitor having a structure that is strongly compressed and tightly adhered without any gaps, and a fluorine-based polymer is contained on the surface of the structure that comes into contact with the rubber sealant, or on both this surface and the surface of the rubber sealant. A liquid-impregnated sealed capacitor characterized by the formation of a film. (2) The surface tension of the fluoropolymer is 15 dyne/
2. The liquid-impregnated sealed capacitor according to claim 1, wherein the liquid-impregnated sealed capacitor has a liquid-impregnated capacitor of less than cm. (3) The liquid-impregnated sealed capacitor according to claim 1, wherein electrical insulating oil is used as the liquid impregnating agent. (4) The liquid-impregnated sealed capacitor according to claim 1, wherein the compressibility of the rubber sealant is 40% or less.