JPH0593034U - Electrolytic capacitor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a low-profile aluminum electrolytic capacitor with few short-circuit defects. [Structure] A capacitor element formed by alternately winding a strip-shaped separator and an electrode foil having a width narrower than that of a separator,
In an electrolytic capacitor which is housed in a cylindrical outer case made of metal with a bottom and the opening is hermetically sealed with a sealing body,
Two separators having different widths are used as the separators of the capacitor element, and the lower end 1a of the wider separator 1 located on the bottom side of the outer case 6 extends below the lower end of the other separator 2. When the capacitor element is wound in such a manner that the capacitor element is pushed into the outer case, the lower end portion 1a of the outermost peripheral wide separator 1 bends inward along the curved peripheral portion 6a of the bottom portion, As you can see, the lower ends of the other wide separators that are located every other bend inward, and the bent lower ends of the wide separators are the lower end of the electrode foil and the inner wall of the bottom of the outer case. It is placed between and.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electrolytic capacitor.

[0002]

[Prior Art]

 An electrolytic capacitor, for example, an aluminum electrolytic capacitor, is made of, for example, aluminum with a bottomed tubular shape and a capacitor element in which an anode foil and a cathode foil made of aluminum foil are wound with a separator between them and impregnated with a predetermined electrolytic solution. It is housed in an outer case and its opening is hermetically closed with a sealing body. That is, a strip-shaped anode foil and cathode foil, and a separator of the same width wider than these electrode foils, which are stacked in the order of anode foil, separator, cathode foil, and separator, are used as a winding capacitor element.

[0003]

[Problems to be solved by the device]

 However, depending on the type of aluminum electrolytic capacitor, there is a strong demand for a lower height, which makes it necessary to reduce the height of the outer case. Therefore, the width of the separator and the electrode foil that make up the capacitor element are narrowed, and the difference between the two is also small. Therefore, the electrode foil and terminals of the capacitor element installed in the outer case may come into contact with the bottom inner wall of the outer case and cause a short circuit due to winding misalignment during the winding process. There was a limit to how large it could be and how low it could be.

For this reason, while using the same low-profile outer case, a separator with a wider width than before is used for winding, and when this is inserted into the outer case, it is pushed firmly and the lower end of the separator is peeled off. I tried to bend it and put it in a low-profile outer case, but the separator rebounded and did not easily reach the specified height. In addition, the bending direction of the lower end of the separator was uneven, and in some cases, the electrode foil and terminals could come into contact with the inner wall of the outer case and cause a short circuit.

An object of the present invention is to provide a low-profile aluminum electrolytic capacitor with less short circuit defects.

[0006]

[Means for Solving the Problems]

 In the present invention, a capacitor element formed by alternately sandwiching a strip-shaped separator and an electrode foil narrower than a separator and winding the capacitor element is housed in a cylindrical outer case made of metal and having an opening. In an electrolytic capacitor that is hermetically sealed with a sealing body, the peripheral edge of the bottom of the outer case is curved, and two separators with different widths are used as the separator of the capacitor element. The lower end of the outer case located on the bottom side is wound so as to extend below the lower end of the other separator. Further, the difference in width between the two separators is configured to be equal to or more than the thickness obtained by adding the thickness of the electrode foil and the thickness of the terminal attached to the electrode foil.

[0007]

[Action]

 When pushing the cylindrically wound capacitor element into the bottomed outer case, the lower end of the wider outermost separator bends inward along the curved peripheral edge of the bottom, As you can see, the lower ends of every other wide separators bend inward, and the curved lower ends of the wide separators are placed between the lower end of the electrode foil and the inner wall of the bottom of the outer case. This part prevents contact between the electrode foil or terminal and the inner wall of the bottom of the outer case.

[0008]

【Example】

 FIG. 1 is a cross-sectional view showing a part of a state before being inserted in an outer case of a capacitor element formed by winding a strip-shaped electrode foil and a separator. The capacitor element is a first separator 1 and an electrode foil. The anode foil 3, the second separator 2, and the cathode foil 4, which form the electrode foil, are wound in multiple layers in this order to form a tubular shape. Each of the strip-shaped anode foils 3 and cathode foils 4 is fitted with a tab terminal 5 consisting of a round bar having a flat portion in contact with the foil, and the upper end of the tab terminal 5 is a sealing member. It penetrates the body and is pulled out.

The width A of the first separator is wider than the width B of the second separator 2, and the width B of the second separator 2 is wider than the width C of the anode foil 3 and the cathode foil 4. The upper ends of the first and second separators 2 both have the same height, and preferably extend at least the thickness of the electrode foils and above the upper ends of both electrode foils. On the other hand, the lower end portion of the second separator 2 also extends below the lower end portion of the electrode foil by at least the thickness of the electrode foil. The first separator 1 extends further below the lower end of the second separator 2. The difference D in width between the first separator 1 and the second separator 2 is preferably equal to or more than the sum of the thickness of the electrode foil and the thickness of the flat portion of the terminal 5.

As shown in FIG. 2, the capacitor element thus wound in a cylindrical shape is pushed into the bottomed outer case 6 having a curved peripheral edge portion 6 a and pressed by the sealing body 7. Then, the lower end portion 1a of the first outermost separator 1 having a wide width bends inward along the curved peripheral portion of the bottom portion, and as is learned from that, the other first separators 1 The lower end bends inward. Each curved lower end portion 1a of the first separator 1 serves as an insulator and is positioned between the lower end portion of the electrode foil and the inner wall of the bottom portion of the outer case, so that the capacitor element is strongly and deeply pressed. This prevents the electrode foil and tab terminals from coming into contact with the inner wall of the bottom of the outer case and causing a short circuit. The upper end portion of the tab terminal 5 penetrates the sealing body 7 and is drawn to the outside. The outer edge of the outer case 6 is then subjected to drawing and curling to fix the sealing body 7.

The widths of the two electrode foils 3 and 4 do not necessarily have to be the same. Also, the heights of the upper ends of the first and second separators need not be the same. Further, the peripheral edge portion 6a of the bottom portion of the outer case 6 is sufficient since the outer case formed from the plate body is curved as in the past, but the lower edge portion of the wide separator is bent inward. It may be further curved to make it easier.

As shown in Table 1 below, a capacitor element (electrode foil width of 2.2 mm) in which the widths of the two separators are changed (Examples 1 and 2) and a separator having the same width of the two separators under the same conditions. And a capacitor element (conventional example) using the same were manufactured, and the rate of short-circuiting by pushing this capacitor element into the outer case (diameter 4 mm) with an external force of 1 kg / cm ² was investigated. The rating of the electrolytic capacitor formed using these capacitor elements is 35V 4.7 μF.

Table 1 Separator width Height of outer case Shorting rate Example 1 3.0mm / 3.2mm Average 5.8mm 0 out of 1000 pieces Example 2 2.7mm / 3.0mm Average 5.6mm 0 out of 1000 pieces Conventional example 3.0mm /3.0mm Average 5.8mm 3 out of 1000

From these results, it can be seen that the electrolytic capacitor according to the present invention has a lower short-circuit rate than the conventional electrolytic capacitors, even though the height of the outer case is the same or lower. .

[0015]

[Effect of the device]

 In the present invention, the lower end of each separator that extends downward from the wound capacitor element is long, so that the lower end of the wide separator is pushed when the capacitor element is pushed into the outer case. The bent part is easy to bend, and it also bends inward along the shape of the rounded peripheral edge of the bottom of the outer case, so that other wide separators also bend inward, so this bent part is insulated As a body, it prevents contact between the electrode foil and terminals and the inner wall of the bottom of the outer case, and can reduce the height of the electrolytic capacitor without worrying about short circuits.

Further, even when an outer case having the same height as that of the conventional case is used, the possibility of short circuit failure can be significantly reduced.

Further, by increasing the width of the separator, the holding amount of the electrolytic solution is improved, and the life of the capacitor can be extended.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a part of a capacitor element of an electrolytic capacitor of the present invention before being put in an outer case.

FIG. 2 is a partial cross-sectional view showing a state in which a capacitor element is inserted in an outer case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st separator 1a Lower end part of 1st separator 2 2nd separator 3 Electrode foil (anode foil) 4 Electrode foil (cathode foil) 5 Tab terminal 6 Exterior case 6a Bottom peripheral part

Claims (2)

[Scope of utility model registration request] 1. A capacitor element formed by alternately sandwiching and winding a strip-shaped separator and an electrode foil having a width narrower than that of a separator is housed in a cylindrical outer case made of metal and having an opening. In an electrolytic capacitor obtained by hermetically sealing a container with a sealing body, two separators having different widths are used as separators of the capacitor element, and the lower end of the wider separator is located on the bottom side of the outer case. The electrolytic capacitor is wound so as to extend downward from the lower end of the separator. 2. The electrolytic capacitor according to claim 1, wherein the difference in width between the two separators is not less than the sum of the thickness of the electrode foil and the thickness of the terminals attached to the electrode foil.