JPS612314A - Wound-type metallized film condenser - 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 relates to an improvement in a wound metallized film capacitor which is provided with a safety mechanism in the event of dielectric breakdown by dividing a metal vapor deposited electrode.

(Conventional configuration and its problems) Conventional metallized film capacitors, which are formed by dividing and winding metal vapor-deposited electrodes, have a structure that consists of a collection of microcapacitors connected by a sprayed metal layer. , when dielectric breakdown occurs between opposing electrodes at a certain point, the split electrodes involved in the dielectric breakdown are electrically disconnected from the capacitor body and released, reducing the negative impact on other microcapacitor groups. . Because of this function, even in the unlikely event that an abnormal voltage is applied to the capacitor or the ambient temperature rises to an abnormally high temperature, the capacitance will simply decrease, avoiding the worst case scenario of smoke or fire. We were able to. This function is called a security mechanism.

The safety mechanism is basically obtained by separating the vapor-deposited electrode of at least one of the metallized films la and lb to form a divided electrode 2, as shown in Fig. 1, but the mechanism can be further improved. In order to improve this, a method has already been proposed in which, as shown in FIG. 2, a part of the divided electrode 2 is also provided with a blank space to increase the current inflow density at the time of dielectric breakdown. In FIG. 2, numeral 3 indicates a vapor deposited film removal section provided intermittently in the longitudinal direction of the metallized film. The vapor deposited film removing section 3 also includes one in which a vapor deposited film is not partially formed during vapor deposition.

However, when the capacitance of a capacitor becomes large, such as several tens of μF, the operating rate of the safety mechanism may decrease compared to a low-capacity capacitor, and this can be improved by the capacitor structure shown in Figure 2. There are limits to this method.

The areas where the safety mechanism is insufficient are limited to areas close to the winding core, and the reason for this is that the metallized film is wound around a hard winding core made of winding film or plastic molded products. This was the mechanical pressure generated in the direction of the winding core.

Figure 2 shows a 5 μm thick double-sided metallized polyethylene phthalate film and a 5 μm thick double-sided metallized polyethylene phthalate film with one side partially removed at regular intervals so that the split width of the split electrode is 40 cm and the removal rate near the metal sprayed layer is 80%. Figure 3 shows the results of dismantling and investigating 20 test products that were found to be malfunctioning after testing 5 μF samples made of 51 trn non-metalized polyethylene phthalate film wound around them, and showing the results in Figure 3. . As is clear from the figure, most of the fractured areas are concentrated near the winding core. In addition, Fig. 3(a)
, (b), d is the thickness of the wound film.

These results show that when a capacitor with a large capacitance is used, the outer diameter of the wound element is large, and the mechanical pressure generated in the vicinity of the winding core increases significantly compared to the outer circumference of the wound element, which increases the mechanical stress generated when the safety mechanism operates. Smoke and ignition occur because the energy exceeds the mechanical strength near the winding core.

FIG. 4 is a cross-sectional view of a conventional wound dry metallized film capacitor. In this capacitor, since the inside of the winding core 4 is filled with thermosetting casting resin 5, the mechanical pressure in the winding core direction is strong.

(Objective of the Invention) An object of the present invention is to eliminate the drawbacks of the conventional example and to create a hollow space inside the winding core in order to relieve the mechanical pressure generated when the safety mechanism of the capacitor winding core operates. Structure of the Invention) The wound metallized film capacitor of the present invention is a metallized film capacitor in which at least one vapor-deposited film electrode of electrodes facing each other with a dielectric interposed therebetween is divided into a plurality of electrodes in the longitudinal direction. is hollowed out. Further, at least one of the divided electrodes has vapor deposited film removal portions intermittently in the longitudinal direction of the metallized film. Further, the inside of the core is hollowed out using adhesive tape or a sealing plug.

The winding core is made of a plastic molded product or plastic film having a heat deformation temperature of 80° C. to 160° C., or is made of a thermosetting resin such as resin.

(Description of Embodiment) An embodiment of the present invention will be described based on FIGS. 5 to 7.

5 and 6 are cross-sectional views of wound metallized film capacitors of the present invention.

In FIG. 5, both ends of the winding core 4 are sprayed with metal, and then adhesive tapes 6 are adhered to both ends to prevent the casting resin 5 from entering the inside of the winding core 4. Similarly, in the case shown in FIG. 6, after the capacitor element 8 is completed, both ends of the winding core 4 are sealed using the sealing plug 7, and then the metal spraying 9 is carried out to prevent the casting resin 5 from entering. This is a wound type dry metallized film capacitor with a hollow core 4. As the sealing plug 7, a plastic molded product, rubber, cork, etc. can be used. 10 is a lead wire, and 11 is a case.

Next, as a specific example of the present invention, a capacitance of 50 μF is shown.
We will discuss the case where the capacitor is constructed by metalizing both sides of polyethylene terephthalate film.

The vapor-deposited electrode on one side of a double-sided metallized film with a width of 62 mm formed by vacuum-depositing aluminum Mk shadows on both sides of a polyethylene terephthalate film with a thickness of 5 μm is made into a divided electrode with a dividing width of about 40 mm, as shown in FIG. Further, parts of the vicinity of the metal sprayed layer are intermittently removed at regular intervals so that the removal rate is 80%.

The division processing and removal processing are performed by electrical discharge processing. The thus treated double-sided metallized film and 60 polyethylene terephthalate films each having a thickness of 5 μm and a width were stacked and wound to form a capacitor.

The table shows the results of comparing the sample shown in FIG. 5 with a hollow core and the conventional capacitor sample shown in FIG. 4 in which the core is filled with casting resin.

As a safety mechanism test for these samples, the
VAC was applied to forcibly cause dielectric breakdown, and the presence or absence of smoke or ignition at that time was investigated.

It can be seen from the table that the effect of relieving mechanical pressure in the winding core is extremely large. As is clear from the disassembled cross-sectional view of the product of the present invention after the safety mechanism test shown in Figure 7, the winding core 4 is deformed, and the mechanical pressure in the direction of the winding core when the safety mechanism is activated deforms the winding core. It can be seen that the situation has been relaxed.

The core material is epoxy or polyethylene.

Polypropylene, polycarbonate, polyvinyl chloride, nylon, phenol, polybutylene.

, le There are materials such as polyethylene terephthalate, acrylic, and polystyrene. In the above embodiments, the case of a capacitor made of polyethylene terephthalate film was explained, but in addition, there are cases where a metalized polynolopylene film is used, or a capacitor made of a metalized (IF') ethylene prephthalate film and a polypropylene film. The same effect can be obtained even if

(Effects of the Invention) According to the present invention, the self-protection mechanism of a large-capacity capacitor, which has been difficult to operate in the past, can be stably operated to prevent smoke or ignition even when dielectric breakdown occurs.

Therefore, no special protection device is required, and the device can be made smaller, which is advantageous both industrially and economically.

[Brief explanation of the drawing]

Figures 1 and 2 are perspective views of the electrode structure of the right metallized film capacitor with a conventional safety mechanism, and Figure 3 (
a) and (b) are a summary chart of the investigation of the broken elements and an explanatory diagram of the thickness of the wound film of the defective product of the same safety mechanism, and Figure 4 is a cross-sectional view of the same wound type metallized film capacitor. 5 and 6 are cross-sectional views of a wound metallized film capacitor according to an embodiment of the present invention, and FIG. 7 is a cross-sectional view of the wound metallized film capacitor after the safety mechanism operation test. . 1 a + 1 b...Metalized film, 2... Divided electrode, 3... Deposited film removal part, 4... Winding core, 5...
・Casting resin, 6. Adhesive tape, 7. Sealing plug, 8.
...Capacitor element, 9.Metal spraying, 10.Lead wire, 11.Case. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (5)

[Claims] (1) A metallized film capacitor in which at least one vapor-deposited film electrode of the electrodes facing each other with a dielectric film interposed therebetween is divided into a plurality of parts in the longitudinal direction, characterized in that the inside of the winding core is hollowed. Wound metallized film capacitor. (2) The wound metallized film capacitor according to claim (1), characterized in that the metallized film of at least one of the divided electrodes has intermittently vapor-deposited film removal portions in the longitudinal direction of the metallized film. (3) Claims (1) or (2), characterized in that the winding core is sealed at both ends inside with adhesive tape or a sealing plug, and the inside is hollow. Wound metallized film capacitor. (4) The winding core is made of a plastic molded product or plastic film with a heat deformation temperature of 80°C to 160°C, as described in any one of claims (1) to (3). Wound metallized film capacitor. (5) The winding according to any one of claims (1) to (4), characterized in that a thermosetting resin such as epoxy resin is filled between the capacitor element and the case. type metallized film capacitor.