JPH11251201A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor having a structure for fixing a capacitor element which prevents internal terminals of the capacitor element from breaking due to metal fatigue by suppressing the movement of the internal terminals due to vibration, even if the capacitor element vibrates in a metallic case when the electrolytic capacitor is subjected to vibration. SOLUTION: One end of a capacitor element 2 is covered with a cap 9, and tabs 4 are inserted through the hole 30 of the cap 9 for connecting with external terminals inside of a sealing lid. The capacitor element 2 is contained in a metallic case 13, and the metallic case 13 is sealed and crimped circularly along the rim of the cap 9 to fox the capacitor element 2 via the cap 9, which eliminates the need for an agent for fixing the element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor having an improved structure for fixing a capacitor element housed in a metal case.

[0002]

2. Description of the Related Art In FIG. 3, reference numeral 2 denotes a capacitor element formed by winding each of an anode foil and a cathode foil through electrolytic paper and winding a resin-made tape 10 around the periphery thereof. The electrolytic capacitor 1 is housed in a cylindrical metal case 3 having a bottom. Reference numeral 4 denotes a tab of the capacitor element 2, which is electrically connected to each of the anode foil and the cathode foil and is drawn out from the end face of the capacitor element 2. Numeral 5 is a cylindrical sealing plate having an annular step on the outer periphery, and a pair of external terminals (screw terminals) 6 are fixed through. The internal terminal 4 is joined to an external terminal 6 through which a cylindrical sealing plate 5 is inserted. Reference numeral 7 denotes an element fixing agent that fills a gap between the metal case 3 and the capacitor element 2 so that the capacitor element 2 does not vibrate in the metal case 3.

The element fixing agent 7 is filled in a state of being melted by heat in advance, such as coal tar, and is thermoplastic, which is cooled and solidified, or thermosetting, which is filled with heat and then cured by heat, such as epoxy resin. Is used. When the element fixing agent 7 filled in the metal case 3 hardens, the sealing plate 5 is fitted into the opening end of the metal case 3. A rubber 8 having a square ring shape is arranged on the annular step portion of the sealing plate 5. In this state, the opening end of the metal case 3 is swaged to fix the sealing plate 5 to the metal case 3.

[0004]

An electrolytic capacitor requires a hollow air reservoir inside to reduce the rise in internal pressure due to gasification of an electrolytic solution impregnated in a capacitor element housed in a metal case by applying a voltage. And Therefore, it is necessary to provide a gap between the metal case and the capacitor element.If the electrolytic capacitor receives vibration, the capacitor element vibrates with the swing width of the gap provided between the metal case and the capacitor element, The internal terminal (tab) of the capacitor element is disconnected. In order to prevent such disconnection of the internal terminals, in a conventional electrolytic capacitor, a gap between the inside of the metal case and the capacitor element is filled with an element fixing agent so that the capacitor element does not vibrate in the metal case.

[0005] However, the electrode foil used in the manufacture of capacitor elements generally has a slightly different capacity per unit area for each lot (roll in which a fixed amount is wound). Even in the case of manufacturing a capacitor element, the length of the electrode foil wound around a certain capacity is slightly different depending on the lot of the electrode foil used. Therefore, in the manufacturing process of an electrolytic capacitor where there is not enough space between the metal case and the capacitor element, the amount of the element fixing agent filled in the bottom of the metal case is adjusted according to the length of the electrode foil used for the capacitor element There is a need for an electrolytic capacitor having an element fixing structure that reduces the influence of vibration of the capacitor element without using an element fixing agent.

According to the present invention, when the electrolytic capacitor is subjected to vibration, the capacitor element 2 does not vibrate in the metal case 3 so that the swing of the internal terminal (tab) is limited and the internal terminal (tab) is restricted.
It is an object of the present invention to provide an electrolytic capacitor having an element fixing structure for preventing disconnection due to metal fatigue.

[0007]

An electrolytic capacitor according to the present invention comprises: a capacitor element having an electrode foil wound around an electrolytic paper and a tab for extracting an electrode drawn out from an end face; a sealing plate for fixing an external terminal; A cap formed of an insulating member having an opening at one end and having a hole at the center of the bottom surface, and covering the cap at one end of the capacitor element, inserting the tab through the hole of the cap, and closing the sealing plate. It is connected to the external terminal on the inner surface side of the cap, housed in a metal case with one end opened, and caulking the metal case annularly along the outer peripheral portion of the cap to fix the capacitor element via the cap. It is characterized by having done. And
In order to fix the capacitor element more firmly, the cap is preferably made of elastic rubber. Preferably, a recess is formed in the inner surface of the bottom surface of the metal case, and the other end of the capacitor element is accommodated in the recess. in this case,
When a concave portion is formed on the inner surface of the bottom surface of the metal case by press molding, the outer surface of the bottom surface of the metal case is formed as a convex portion.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. 1 (a) and 1 (b) and the drawing shown in FIG. FIG. 1A is a cross-sectional view showing a first embodiment of the electrolytic capacitor of the present invention.
(B) is a perspective view showing a cap used in the embodiment, and FIG. 2 is a sectional view showing a second embodiment of the electrolytic capacitor of the present invention. Also, FIGS. 1A and 1B and FIG.
The same reference numerals as those shown in FIG. 3 indicate the same components.

In FIG. 1 (a), reference numeral 2 denotes a capacitor element formed by winding each of an anode foil and a cathode foil via electrolytic paper and winding a resinous tape 10 around the periphery thereof. A pair of tabs 4 for extracting electrodes are pulled out from one end surface of the foil. The cap 9 shown in FIG. 1B is formed of an insulating member such as a resin or an elastic rubber, but may be formed of an elastic rubber in order to enhance the joining property of the cap 9.
The cap 9 has a cylindrical shape with one end opened, and has a hole 30 formed in the center of the bottom surface. One end of the metal case 13 is open, and the concave portion 12 is formed on the inner surface at the center of the bottom surface. One end of the capacitor element 2 on the side from which the tab 4 is drawn out is covered with a cap 9 so that a pair of tabs 4
Has been inserted. The pair of tabs 4 are respectively connected to a pair of external terminals 6 on the inner surface side of the sealing plate 5.

In this state, the capacitor element 2 is housed in the metal case 13 together with the sealing plate 5 with the sealing plate 5 side up.
The other end of the capacitor element 2 is fitted into a concave portion 12 provided on the inner surface of the bottom surface of the metal case 13. Then, the opening end of the metal case 13 is swaged and a sealing plate is
15 is fixed. On the other hand, the metal case 13 is crimped annularly along the outer peripheral portion of the cap 9 located below the sealing plate 15. Therefore, the inner surface of the metal case 13 protrudes annularly, and the protruding portion comes into contact with the outer peripheral surface of the cap 9 to hold the peripheral surface of the capacitor element 2. Further, since the main body of the capacitor element 2 is sandwiched between the concave portion 12 formed on the bottom surface and the inside of the cylinder of the cap 9, the capacitor element 2 is securely fixed in the metal case 13.

FIG. 2 shows a metal case having a flat outer surface on the bottom surface.
13 shows an electrolytic capacitor according to another embodiment of the present invention which employs a metal case 23 in which the outer surface of the bottom surface is formed in an annular convex portion instead of the bottom surface 13. That is, in FIG. 2, the metal case 23 is formed in a flat plate shape with a thin bottom surface, and when the concave portion 22 is formed in the inner surface of the central portion of the bottom surface by press molding or the like, the outer surface of the bottom surface of the metal case 23 becomes correspondingly outward. And the outer surface of the bottom surface is formed as a projection.

In FIG. 2, reference numeral 2 denotes a capacitor element formed by winding each of an anode foil and a cathode foil via electrolytic paper and wrapping a resin winding tape 10 around the periphery thereof. A pair of tabs 4 is pulled out from one end face. The cap 9 has a cylindrical shape with one end opened, and has a hole 30 formed in the center of the bottom surface. One end of the metal case 23 is open, and a concave portion 22 is formed on the inner surface at the center of the bottom surface. One end of the capacitor element 2 on the side from which the tab 4 is pulled out is covered with a cap 9, and a pair of tabs 4 is inserted through the hole 30. The pair of tabs 4 are respectively connected to a pair of external terminals 6 on the inner surface side of the sealing plate 5.

In this state, the capacitor element 2 is housed in the metal case 23 together with the sealing plate 5 with the sealing plate 5 side up.
The other end of the capacitor element 2 is fitted into a recess 22 provided on the inner surface of the bottom surface of the metal case 23. Then, the opening end of the metal case 23 is swaged and a sealing plate is
15 is fixed. On the other hand, a metal case 23 is crimped annularly along the outer peripheral portion of the cap 9 located below the sealing plate 15. Therefore, the inner surface of the metal case 23 protrudes in an annular shape, and the protruding portion comes into contact with the outer peripheral surface of the cap 9 to hold the peripheral surface of the capacitor element 2 and to form the concave portion 22 in which the body of the capacitor element 2 is formed on the bottom surface The capacitor element 2 is securely fixed in the metal case 23 by being sandwiched between the inside of the cylinder of the cap 9. In the two embodiments shown in FIGS. 1 and 2, a concave portion is formed on the inner surface of the bottom surface of the metal case and the capacitor element is fitted. However, when the capacitor element is sufficiently fixed by the cap, It is not necessary to form the recess.

[0014]

According to the electrolytic capacitor of the present invention, one end of the capacitor element is covered with an elastic cap, and a tab pulled out from this end is inserted into the hole of the cap and connected to the external terminal on the inner surface side of the sealing plate. Then, with the capacitor element housed in the metal case, the opening end of the metal case is swaged to clamp the main body of the capacitor element in the cap cylinder to fix the capacitor element. Then, the metal case is annularly crimped along the outer peripheral portion of the cap over one end of the capacitor element so that the inner surface of the metal case protrudes annularly, and the protruding portion comes into contact with the outer peripheral surface of the cap and the capacitor element Since the structure for holding the peripheral surface of the capacitor is adopted, the capacitor element can be securely fixed in the metal case without using an element fixing agent. In addition, the cap is formed of elastic rubber to enhance the bondability of the cap, or a concave portion is provided on the bottom surface of the metal case, and the open end of the metal case is swaged with the other end of the capacitor element housed in the concave portion. Thus, the practical effect is large, for example, the capacitor element body is sandwiched between the concave portion and the inside of the cap cylinder, so that the capacitor element can be more securely fixed.

[Brief description of the drawings]

FIG. 1A is a sectional view showing a first embodiment of the electrolytic capacitor of the present invention. (B) is a perspective view showing a cap used in the example.

FIG. 2 is a sectional view showing a second embodiment of the electrolytic capacitor of the present invention.

FIG. 3 is a sectional view of a conventional electrolytic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrolytic capacitor 2 Capacitor element 3 Metal case 4 Tab 5 Sealing plate 6 External terminal 7 Element fixing agent 8 Rubber 9 Cap 10 Winding tape 11 Electrolytic capacitor 12 Recess 13 Metal case 21 Electrolytic capacitor 22 Recess 23 Metal case 30 Hole

Claims (4)

[Claims] 1. A capacitor element in which an electrode foil is wound through an electrolytic paper and a tab for extracting an electrode is drawn out from an end face;
A sealing plate to which an external terminal is fixed, a cap formed by an insulating member having an opening at one end and having a hole at the center of the bottom surface, the cap being covered on one end of the capacitor element, and the tab being covered with the cap. And is connected to an external terminal on the inner surface side of the sealing plate and is housed in a metal case having one end opened, and the metal case is crimped in an annular shape along the outer peripheral portion of the cap to pass through the cap. An electrolytic capacitor characterized in that the capacitor element is configured to fix the capacitor element. 2. The electrolytic capacitor according to claim 1, wherein said cap is formed of elastic rubber. 3. The electrolytic capacitor according to claim 1, wherein a concave portion is formed in an inner surface of a bottom surface of the metal case, and the other end of the capacitor element is accommodated in the concave portion. 4. The electrolytic capacitor according to claim 3, wherein the bottom surface of the metal case has a concave portion formed on the inner surface so that the outer surface of the bottom surface of the metal case is formed as a convex portion.