JPH0416929B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a capacitor equipped with a safety function that operates under all conditions. Conventional configurations and their problems Conventionally, there are two methods for adding safety functions to the capacitor itself: One is the method of incorporating a temperature fuse into the capacitor, which is described in Japanese Patent Publication No. 45-14621, and the other is the method of dividing the electrodes, which has already been proposed by the present inventors. be. However, each method has its own drawbacks. In other words, in a capacitor with a built-in temperature fuse, in the event of so-called thermal runaway, such as when the ambient temperature rises abnormally, the temperature fuse will easily melt and the safety function will be activated. In the case of short-term breakdown due to overvoltage (DC, AC, DC+AC, or pulsed voltage), the temperature fuse may not melt and the safety function may not operate. Conversely, a capacitor with a split electrode configuration will easily activate its safety function in the event of breakdown due to overvoltage.
It has the disadvantage of being difficult to operate in the event of destruction due to thermal runaway. OBJECTS OF THE INVENTION The present invention relates to a resin-clad metallized film capacitor, and in particular, an object of the present invention is to provide a highly reliable capacitor with a safety function when using an alternating current voltage. Structure of the Invention In the capacitor of the present invention, at least one vapor-deposited electrode of the electrodes facing each other via a dielectric is divided into a plurality of parts, and a plurality of vapor-deposited film blanks are formed along the edges of the divided electrodes to be metal-sprayed. By providing multiple parts, it becomes multiple small current capacity parts, and it also has a built-in temperature fuse with a melting temperature of 80°C to 200°C. Capacitors whose dielectric material is made of plastic film, especially capacitors using polyethylene terephthalate dielectric material, have a relatively large dielectric loss, so that the possibility of destruction not only due to overvoltage but also due to thermal factors is generally high. In such a case,
If an overvoltage is applied in a state of overheating for some reason, unlike at low temperatures, a phenomenon of partial breakdown with small discharge pulse energy occurs, making it difficult to operate safely with conventional temperature fuses. In addition, with only conventional split electrodes, a special breakdown condition occurs that is difficult to disconnect, but by forming multiple small current capacity parts together with the split electrodes, disconnection is easily possible even under the above conditions. becomes. Furthermore, by having multiple small current capacity parts, compared to a single part, accidental disconnection phenomena such as scratches on the deposited film or single partial breakage can be suppressed, resulting in a more reliable capacitor. It will be configured. In addition, by using the above capacitor structure and a temperature fuse in combination, there is no need to use a temperature fuse with a low melting temperature, as in the past, and a high temperature fuse can be used. This makes it possible to provide a capacitor with excellent workability in the manufacturing process and with stable capacitor characteristics. Description of Examples Examples of the present invention will be described below. 1st
2 and 3 show respective embodiments of the present invention. In the figures, 1 is a capacitor element having a split electrode configuration, which will be described later, 2a and 2b are metal sprayed parts, and 3
a, 3b are lead wires, 4 is a temperature fuse inserted in the middle of the lead wire 3b, 5 is a capacitor element 1
An insulator made of liquid, solid, or gas that covers the In addition, in FIG. 3, 6 is a winding core bobbin. The temperature fuse 4 is preferably located outside the capacitor element 1 as shown in FIG. 1 or inside the capacitor 1 as shown in FIG. It is preferable to set it inside the core bobbin 6 as shown in FIG. By doing so, it is possible to provide a capacitor that is excellent in terms of workability and characteristics. Furthermore, the melting temperature of the temperature fuse 4 is preferably 80°C to 200°C in view of the breakdown temperature of the capacitor. If it is less than 80°C, the workability and reliability of the capacitor will deteriorate, which is undesirable, and if it exceeds 200°C, the temperature fuse will essentially stop functioning, so it is not suitable. Further, in order to more easily operate the safety function against destruction due to overvoltage, the following process can be performed.
That is, inside at least one of the divided electrodes,
Vapor deposition electrode portions having a smaller current capacity than other vapor deposition electrode portions can be provided in a band-like and intermittent manner along the edge of the electrode to be metal sprayed. The present invention will be explained below using specific examples. Electrodes were provided by vacuum-depositing aluminum on both sides of a polyethylene terephthalate (hereinafter abbreviated as PET) film (6 μm thick).
At this time, a pattern as shown in FIG. 4 was provided on one side by masking to form a divided electrode. In the figure, 7 is a plastic film such as PET film, 8 is a divided vapor deposition electrode, and 9 is a plastic film such as PET film.
10 is an electrode dividing line, 10 is a margin portion, 11 is a deposited film blank portion, 12 is a small current capacity portion, and A is a metal spraying direction. Also l ₁ = 62mm, l ₂ = 3mm, l ₃ = 33.5mm, l ₄
= 1.5 mm, l ₅ = 0.5 mm, l ₆ = 8 mm, and l ₇ = 0.5 mm. In the above pattern, a series of vapor-deposited film blank parts 11 are provided along the edge of the electrode where metal is sprayed, so the current capacity of this part is smaller than that of other parts. The size of the vapor deposited film blank part 11 is
They are rectangular, 0.5mm x 8mm, and lined up at 0.5mm intervals. Also, the average resistance of the deposited film is 2.5~
It was 4.5Ω/□. This double-sided vapor deposited PET film and the composite film are made of polypropylene (hereinafter referred to as
Using a film (abbreviated as PP) (thickness 5 μm),
This was layered and wound around a core bobbin to obtain a wound capacitor element with a capacitance of 50 μF. This capacitor element was subjected to metal spraying and heat aged. Next, when attaching the lead wires, a temperature fuse (rated current: 10A) with a blowing temperature of 126°C was attached to the middle of one of the lead wires, and was positioned within the core bobbin as shown in Figure 3. Next, after covering with epoxy resin, a destructive test was conducted. A total of 40 samples were made, and 20 were distributed to each test. The test involves placing a capacitor that has been left at room temperature in a 150°C hot air constant temperature bath, immediately applying the rated voltage (230VAC) to the capacitor, and leaving it for 24 hours to check for smoke or ignition from the capacitor. It is an observational test. The test involves placing the capacitor in a hot air constant temperature oven set at the capacitor's maximum operating temperature (65°C), and after the capacitor reaches 65°C, a voltage (920VAC) four times the rated voltage is applied, and the capacitor is left for one hour. This is a test to observe smoke and ignition from the capacitor. The results are shown in Table 1 below.

[Table] As a result, the safety function worked in all cases in both tests, and there was no smoke or ignition. In addition, while all of the test samples had temperature fuses operating, in the test sample, the temperature fuses did not work, and many were disconnected in the small current capacity section 12 in Figure 4 due to self-healing due to overvoltage. I found out that the safety features were working. For comparison, we created a conventional capacitor and conducted a destructive test. Using a capacitor element with the same split electrode configuration as used in the above example, a capacitor without a built-in temperature fuse but coated with epoxy resin was obtained. Samples and tests were conducted on 10 samples each. The results are shown in Table 2 below.

[Table] From this result, it can be seen that the safety function of this type of capacitor works during the test, but it is difficult to operate during the test. On the other hand, a double-sided vapor-deposited PET film and a PP film, which are not split electrodes and have been commonly used in the past, with solid vapor deposition on both sides, are layered and wound around a core bobbin.
After making a 50 μF capacitor element, applying metal spraying, and heat aging, when attaching the lead wires, attach a temperature fuse (melting temperature: 126°C) in the middle of one of the lead wires, and wind it as shown in Figure 3. It was located inside the lead bobbin. Next, after covering with epoxy resin, a destructive test was conducted. The results are shown in Table 3 below.

[Table] It was found that this type of capacitor had a safety function that worked in the test, but it did not work in the test. In the above embodiments, a wound type capacitor is shown as an example, but a laminated type capacitor may also be used. Furthermore, although this embodiment uses a dry capacitor as an example, an oil-immersed capacitor may also be used. In addition to PET and PP, the dielectric material used may be polyethylene, polystyrene, polycarbonate, polyvinylidene fluoride, or other films or papers, either alone or in combination. Further, in this embodiment, double-sided deposition of PET was used, but of course a structure in which two single-sided deposited films were stacked may also be used. In addition to the type of winding around a core bobbin, the core bobbin may be made of plastic film, kraft paper, plastic nonwoven fabric, or the like, in addition to a plastic molded product. Effects of the Invention As described above, according to the present invention, it is possible to provide a capacitor having an excellent safety function that operates under all conditions, and its industrial efficiency is great.

[Brief explanation of drawings]

1, 2, and 3 are cross-sectional views of each embodiment of the capacitor according to the present invention, and FIG. 4 is a plan view of a part of the vapor-deposited film used in the capacitor of the present invention. 1...Capacitor element , 2a, 2b...metal sprayed part, 3a, 3b...lead wire, 4...temperature fuse, 5...insulator, 6...core bobbin, 7...
Dielectric material (plastic film, etc.), 8... Divided vapor deposition electrode, 9... Electrode dividing line, 10...
...Margin part, 11... Vapor deposited film blank part, 12...
Small current capacity section, A...Metal spraying direction.

Claims (1)

[Scope of Claims] 1. At least one of the vapor deposition electrodes facing each other via a dielectric material is divided into a plurality of parts, and the vapor deposition is carried out in a band-like manner and intermittently along the edge of the electrode to be sprayed with metal. By providing a membrane blank area, multiple small current capacity parts with a smaller current capacity than other vapor deposition electrode parts are created, and the fusing temperature is 80°C to 200°C.
A capacitor characterized by having a built-in temperature fuse. 2. The capacitor according to claim 1, wherein the capacitor is of a wound type. 3. The capacitor according to claim 2, wherein the temperature fuse is located within the core bobbin of the wound capacitor.