JPS6337486B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitor, and particularly to a capacitor of a wound type capacitor in which an electrode foil and a dielectric material are assembled and wound, in which the electrode foil is improved. Round edge electrode foils with bent ends of the electrode foils, as shown in FIGS. 1 and 2, have already been used as electrode foils to sandwich dielectrics in wound capacitors in order to improve withstand voltage.

Both Fig. 1 and Fig. 2 show cross sections of these electrode foils. In Fig. 1, the bent portion 1 is one in which both ends of the electrode foil in the width direction are continuously bent inward by a certain width. Therefore, the thickness of the bent part is 2
It will be doubled.

In addition, in Fig. 2, the bent part 1 is formed by taking the electrode foil so that it has a wider width and continuously bending it inward, and forming the bent part 1 so that both bent end faces abut at the center in the width direction. Therefore, it is formed to have a cross section exactly like that of two stacked electrode foils.

By the way, in the example shown in Fig. 1, the thickness of the bent part is doubled in some parts, so it is difficult to manage the collective size, capacity management, processing management, etc. After oil immersion, an oil layer is formed, but the thicker the oil layer, the lower the dielectric breakdown voltage, so this portion becomes the weak point of the capacitor's withstand voltage.

The example shown in Fig. 2 is an example for solving the drawbacks of the electrode foil with a bent part shown in Fig. 1, but the bending part is wide and difficult to process. is difficult.

Therefore, in order to solve the above-mentioned problems with electrode foil, the present invention bends both ends of the electrode foil in the length direction, and furthermore, this part is made into a part where the electrode foil does not overlap due to bending. The round edged electrode foil is rolled at the bent end so that it has approximately the same thickness, or only the both ends in the width direction are rolled to a certain width and half the thickness in the width direction. A capacitor element is formed using a round edged electrode foil, etc., which is bent so that it has approximately the same thickness as the non-overlapping portion.

The implementation of the present invention will be described below.

The embodiment shown in FIG. 3 is a sectional view of an electrode foil processed from the conventional electrode foil shown in FIG.

In this case, the electrode foil with both ends in the width direction bent is further rolled with a roller to be rolled to the same thickness as the part of the electrode foil 2 that does not overlap due to the bending, thereby forming the bent portion 1'. In this case, it is necessary to maintain a round edge R on the bending line.

In the example shown in FIG. 4, the width on the inner side in the width direction is rolled by rolling to 1/2 the width, and about 1/2 of this 1/2 thickness is rolled. 2 to the processed surface side, and form a bent part 1'' so that it has the same thickness as the part of the electrode foil 2 that does not overlap by bending.Of course, it is possible to maintain a round edge R at the bent edge. is necessary.

The embodiment shown in FIG. 5 is processed so that it is inclined by a certain width from both ends in the width direction, and about 1/2 of this inclined surface portion is bent to form a bent part 1. This is what I did.

Aluminum foil is usually used as the electrode foil. An embodiment of the present invention is shown in FIG. 6, and an embodiment of the invention is shown in FIG.
Figure shows a partial cross section of a capacitor.

In the figure, 2 is an electrode foil as explained in FIGS. 3, 4, and 5, and 3 is a dielectric material such as paper or plastic film, which is assembled and rolled as shown in the figure. The wound capacitor element 4 is formed by winding.

As shown in Figure 7, the electrode foil is only on one side, and the third
The electrode foil 2 as shown in FIG.
Alternatively, the electrode foil 2 shown in FIG. 3 or 4 can also be used.

If the capacitor elements 4 wound in this manner are assembled into a capacitor element assembly and assembled by a widely known conventional method, an oil-immersed capacitor can be obtained. can be made smaller for the following reasons.

FIG. 8 shows a partial cross section of a conventional capacitor element in which the widthwise end of the electrode foil is bent inward to form a round edge for the purpose of explaining the formula.

In the figure, the electrode foil thickness is te, and the dielectric thickness is
td, oil layer thickness to, and total thickness of electrode foil and dielectric material T _D , capacitor volume Vol=k×T _D /T _D o×(td+to/2/td), where k: coefficient , T _D o: Capacitor element thickness when to and te are equal.

According to the above formula, the capacitor volume (%)
The relationship between and to/te (%) is te=td/10, td/5,
te/2 is shown in the graph of Figure 9.

As is clear from Figure 9, for example, te=td/5
If to = 0 from the indicated line, the volume of the capacitor element assembly will be reduced by about 15%, but considering the actual electrode foil processing accuracy, it is difficult to set to to zero. However, it can be seen that even if to/te is about 30%, the volume can be reduced by about 10%, which greatly contributes to miniaturization.

As explained above, according to the present invention, the ends of the electrode foil in the width direction are bent more narrowly than those in FIG. Since the round edged electrode foil is processed to have approximately the same thickness as the foil portion, it goes without saying that it is possible to increase the partial discharge inception voltage at the end, which is an advantage of capacitors with bent electrode foil. The disadvantage of folded electrode foil capacitors is that the oil layer that forms in the non-overlapping area due to the folded part of the electrode foil can be eliminated, and the dielectric breakdown voltage in this part can be improved, and the electrode thickness at the folded part can be reduced. By reducing the thickness, the volume of the capacitor element can be reduced.

In addition, it becomes easier to manage the collective size and capacity, and it becomes easier to perform drying and impregnation treatments.

[Brief explanation of the drawing]

FIGS. 1 and 2 each show a cross section of a conventional round edged electrode foil. Figure 3, Figure 4, Figure 5
The figures each show a cross section of a round edged electrode foil implemented in the present invention. FIG. 6 shows an embodiment of the present invention, and FIG. 7 is a partial sectional view of the capacitor shown in FIG. FIG. 8 is a partial cross-sectional view of a conventional capacitor element for explaining mathematical formulas. FIG. 9 is a graph showing how the capacitor volume changes when the oil layer thickness changes with respect to the electrode foil thickness. 1, 1', 1'', 1... bending part of electrode foil, 2...
...Electrode foil, 3...Dielectric material, 4...Capacitor element, 5...Counter electrode foil.

Claims (1)

[Claims] 1. Electrode foil with round edges, which is formed by bending both ends of the electrode foil and processing the bent part so that it has approximately the same thickness as the non-overlapping part, or only the ends have a certain degree of thickness in the width direction. An electrode foil with a round edge that has been processed to half the width and half the thickness, and then bent so that this part has approximately the same thickness as the non-overlapping part, or an inclined surface at the end of the electrode foil in the width direction. 1. A capacitor characterized by using a round edged electrode foil which is processed so as to have a slanted surface and bent so as to have approximately the same thickness as the non-overlapping part due to the bending.