JP2012248772A - Electrolytic capacitor and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor achieving high airtightness in a space between an internal metal case and an external metal case, and to provide a manufacturing method of the electrolytic capacitor.SOLUTION: An electrolytic capacitor 1 includes: a capacitor element 2; an internal metal case 5 housing the capacitor element 2 and having a cylindrical shape with a closed bottom; an external metal case 6 covering the internal metal case 5 and having a cylindrical shape with a closed bottom; a sealing member 3 sealing an opening of the internal metal case 5; and narrow parts 5c, 6c respectively provided near an opening end of the internal metal case 5 and near an opening end of the external metal case 6. An elastic member 8 is sandwiched between the narrow part 5c of the internal metal case 5 and the narrow part 6c of the external metal case 6.

Description

  The present invention relates to an electrolytic capacitor adopting a double case structure and a manufacturing method thereof.

In general, an electrolytic capacitor includes a capacitor element impregnated with an electrolytic solution, a bottomed cylindrical metal case containing the capacitor element, and a sealing member that seals an opening of the metal case.
In such an electrolytic capacitor, when an overvoltage, reverse voltage or excessive ripple current exceeding the rated voltage is applied, the electrolytic solution is vaporized due to heat generation of the capacitor element, and the pressure inside the sealed metal case increases. And if this pressure becomes too high, the metal case may rupture or fly away, so a pressure valve is provided on the metal case. It is structured to release pressure to the outside.

  However, when the pressure valve is actuated, a vaporized electrolytic solution (hereinafter referred to as a vaporized electrolytic solution) is discharged through the pressure valve. Therefore, electrolytic capacitors employing a double case structure have been conventionally studied. For example, the electrolytic capacitor 10 described in Patent Document 1 shown in FIG. 3 includes an inner metal case 11 in which a pressure valve 11b is formed on a bottom plate 11a, a bottomed cylindrical outer metal case 12 that covers the inner metal case 11, An absorbent member 13 disposed in a space between the bottom plate 11a of the inner metal case 11 and the bottom plate 12a of the outer metal case 12 is provided.

  In the electrolytic capacitor 10, when the pressure in the inner metal case 11 increases to some extent, the vaporized electrolyte is discharged through the pressure valve 11 b and is quickly cooled and absorbed by the absorbing member 13. Therefore, according to the electrolytic capacitor 10, it is possible to suppress an increase in pressure in the inner metal case 11 and the outer metal case 12.

Japanese Utility Model Publication No. 4-36223

  However, the conventional electrolytic capacitor 10 adopting the double case structure relates to the inner constricted portion 11c and the outer constricted portion 12c formed in the vicinity of the opening ends of the inner metal case 11 and the outer metal case 12 in order to improve the airtightness. There were the following problems.

  That is, if the inner constricted portion 11c of the inner metal case 11 and the outer constricted portion 12c of the outer metal case 12 are simultaneously formed after the inner metal case 11 is covered with the outer metal case 12, the thickness of the metal to be processed becomes large. Since the workability is poor, the shapes of the constricted portions 11c and 12c are displaced, and as a result, the vaporized electrolyte that could not be absorbed by the absorbing member 13 forms a gap between the inner constricted portion 11c and the outer constricted portion 12c. There was a risk of leaking outside.

  Further, when the inner metal case 11 with the inner constricted portion 11c is accommodated in the outer metal case 12 without the outer constricted portion 12c and then the outer constricted portion 12c is formed, that is, with the inner constricted portion 11c Even when the outer constricted portion 12c is formed separately, the adhesion between the metal cases 11 and 12 may be reduced due to processing dimension errors of the inner constricted portion 11c and the outer constricted portion 12c, and the above-described problems may occur.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrolytic capacitor having a high airtightness in the space between the inner metal case and the outer metal case, and a method for manufacturing the electrolytic capacitor. It is to provide.

  In order to solve the above problems, an electrolytic capacitor according to the present invention includes a capacitor element, a bottomed cylindrical inner metal case containing the capacitor element, a bottomed cylindrical outer metal case covering the inner metal case, An electrolytic capacitor comprising a sealing member for sealing an opening of an inner metal case, and a constriction provided near the opening end of the inner metal case and near the opening end of the outer metal case, wherein the constriction of the inner metal case An elastic member is sandwiched between the outer metal case and the constricted portion of the outer metal case.

  According to this configuration, since the elastic member is sandwiched between the constriction portion of the inner metal case and the constriction portion of the outer metal case, even when a deviation occurs in the shape of one or both of the constriction portions. The displacement is absorbed by the deformation of the elastic member, and the airtightness of the space between the inner metal case and the outer metal case can be ensured.

  The elastic member is made of synthetic rubber, for example.

  Further, in order to solve the above problems, an electrolytic capacitor manufacturing method according to the present invention includes an element manufacturing step of manufacturing a capacitor element, an element storing step of storing the capacitor element in a bottomed cylindrical inner metal case, A sealing step of sealing the opening of the inner metal case with a sealing member, a first tightening step of tightening the sealing member by forming a constricted portion near the opening end of the inner metal case, and an elastic member at the constricted portion of the inner metal case Forming a constricted portion in the vicinity of the opening end of the outer metal case, and a case housing step of housing the inner metal case after the elastic member is disposed in a bottomed cylindrical outer metal case. And a second tightening step for tightening the elastic member.

  According to this configuration, since the constricted portion of the outer metal case is formed after the elastic member is disposed in the constricted portion of the inner metal case, even if a deviation occurs in the shape of one or both of the constricted portions, The deformation is absorbed by the deformation of the member, and the airtightness of the space between the inner metal case and the outer metal case can be ensured.

  The manufacturing method may further include a capacitor element aging step between the first tightening step and the case housing step.

  The elastic member is made of synthetic rubber, for example.

  ADVANTAGE OF THE INVENTION According to this invention, the space between an inner metal case and an outer metal case can provide the electrolytic capacitor which has high airtightness, and the manufacturing method of this electrolytic capacitor.

It is a fragmentary sectional view showing one embodiment of the electrolytic capacitor concerning the present invention. It is a flowchart which shows the manufacturing method of the electrolytic capacitor which concerns on this invention. It is a fragmentary sectional view of the conventional electrolytic capacitor.

  Hereinafter, preferred embodiments of an electrolytic capacitor and a method for manufacturing the same according to the present invention will be described with reference to the accompanying drawings.

[Configuration of electrolytic capacitor]
First, the configuration of the electrolytic capacitor according to the present invention will be described with reference to FIG.
As shown in the figure, the electrolytic capacitor 1 seals a capacitor element 2 impregnated with an electrolyte, a bottomed cylindrical inner metal case 5 containing the capacitor element 2, and an opening of the inner metal case 5. A sealing member 3 and a pair of leads 4 for drawing out an anode and a cathode from the capacitor element 2 are provided.

In order to provide a pressure function, the electrolytic capacitor 1 includes a bottomed cylindrical outer metal case 6 covering the inner metal case 5, a bottom plate 5 a of the inner metal case 5 and a bottom plate 6 a of the outer metal case 6 that are separated from each other. And an absorbing member 7 disposed in the space 9 between the two.
At the center of the bottom plate 5a of the inner metal case 5, an inner pressure valve 5b is formed which is thinner than other portions and easily broken. An external pressure valve 6b is formed at the center of the bottom plate 6a of the outer metal case 6 so as to be thinner than other portions and easily broken.

  When the internal pressure of the inner metal case 5 exceeds a predetermined pressure due to heat generation of the capacitor element 2 or the like, the inner pressure valve 5b is broken (opened), and the space in which the inner metal case 5 and the absorbing member 7 are disposed. 9 is connected. When the pressure in the space 9 in which the absorbing member 7 is disposed exceeds a predetermined pressure, the external pressure valve 6b is broken (opens), the space 9 is connected to the outside of the electrolytic capacitor 1, and the electrolytic capacitor 1 is ruptured. Is prevented.

  Even if the temperature of the capacitor element 2 rises and the vaporized electrolyte is discharged through the internal pressure valve 5b, most of the discharged vaporized electrolyte is immediately cooled and absorbed by the absorbing member 7. Therefore, the external pressure valve 6b is opened only when a large amount of the vaporized electrolytic solution that cannot be absorbed by the absorbing member 7 is released from the internal pressure valve 5b vigorously.

  As the absorbent member 7, silica gel, activated carbon, graphite, molecular sieve, diatomaceous earth, bentonite, zeolite, calcium silicate, magnesium aluminate metasilicate, magnesium oxide, magnesium silicate, aluminum silicate, carbon fiber, porous glass , Glass fiber, porous polymer, filter paper, non-woven fabric, gelling agent and the like. Examples of the gelling agent include cellulose, cellulose nitrate, cellulose acetate, hydroxyalkylcellulose, alkylcellulose, and alkali metal salts of carboxyalkylcellulose. Cellulose derivatives comprising, alkali metal salts of alginic acid, gelatin, agar, konjac flour, starch, sugar, polysaccharides, proteins, or a mixture of two or more thereof, or polyvinyl alcohol Copolymer, polyvinyl alcohol derivative, polyvinyl ether derivative, polyvinyl acetate, vinyl acetate-vinyl alcohol copolymer, vinyl acetate-ethylene copolymer, polyethylene, polypropylene, polyisobutylene or a copolymer of two or more What mixed is mentioned.

As shown in FIG. 1, the inner metal case 5 has an inner constricted portion 5c. The inner constricted portion 5c is formed, for example, by pressing a disk-shaped jig near the opening end of the inner metal case 5 to dent the vicinity of the opening end.
The dimensions (width, depth) of the inner constricted portion 5c can be arbitrarily changed by adjusting the shape or pressing force of the jig. By forming the inner constricted portion 5c, the sealing member 3 is tightened, and the airtightness of the inner metal case 5 can be enhanced.

The outer metal case 6 has an outer constricted portion 6c. Similar to the inner constricted portion 5 c of the inner metal case 5, the outer constricted portion 6 c is formed, for example, by pressing a disc-shaped jig near the opening end of the outer metal case 6 to dent the vicinity of the opening end.
As shown in FIG. 1, the outer constricted portion 6c is narrower and slightly shallower than the inner constricted portion 5c. Therefore, in order to form the outer constricted portion 6c, a jig smaller than the jig used when forming the inner constricted portion 5c is required.

  An elastic member 8 is sandwiched between the inner constricted portion 5c and the outer constricted portion 6c. The elastic member 8 is compressed and deformed when the outer constricted portion 6 c of the outer metal case 6 is formed. Therefore, the elastic member 8 is in close contact with both the outer surface of the inner metal case 5 and the inner surface of the outer metal case 6 without a gap.

  As the elastic member 8, for example, any synthetic rubber such as silicone rubber, urethane rubber, acrylic rubber, or the like can be used. On the other hand, a resin such as epoxy resin, polyethylene, or polystyrene is not preferable because it may crack without being deformed when the outer constricted portion 6c is formed, and the airtightness of the space 9 may not be maintained. .

[Method of manufacturing electrolytic capacitor]
Then, with reference to FIG. 2, the manufacturing method of the electrolytic capacitor 1 which concerns on this invention is demonstrated. As shown in the figure, the electrolytic capacitor 1 is manufactured through seven steps (S1 to S7).

  First, in the element manufacturing step S1, a separator is sandwiched between an anode foil and a cathode foil each having an oxide film formed on the surface thereof, and then wound into a cylindrical shape. Make it.

  In the element housing step S2, the capacitor element 2 produced in the previous step S1 is housed in the bottomed cylindrical inner metal case 5. The inner metal case 5 is made of aluminum, for example, and an inner pressure valve 5b is formed in advance at the center of the bottom plate 5a.

  In the sealing step S <b> 3, the sealing member 3 is fitted into the opening of the inner metal case 5 to seal the inner metal case 5. The sealing member 3 is made of a suitable rubber or the like that can withstand an assumed temperature change. The sealing member 3 is previously formed with two through holes for drawing out the pair of leads 4 of the capacitor element 2 to the outside.

  In the first tightening step S4, a disk-shaped jig is pressed near the opening end of the inner metal case 5 to form the inner constricted portion 5c near the opening end, and the sealing member 3 is tightened (compressed). Thereby, the sealing member 3 and the inner metal case 5 are in close contact with each other, and the airtightness of the space in which the capacitor element 2 is accommodated is improved. At the same time, in this step, the opening end (hem) of the inner metal case 5 is also bent.

In the elastic member arranging step S5, the elastic member 8 is arranged on the inner constricted portion 5c formed in the previous step S4.
The mode of disposing the elastic member 8 is as follows: (1) A paste-like resin to be the elastic member 8 is applied to the inner constricted portion 5c and dried. (2) The ring-shaped elastic member 8 is fitted into the inner constricted portion 5c. (3) Wrap a long tape-shaped elastic member 8 having an adhesive surface around the inner constricted portion 5c. (4) Cover the tube-shaped elastic member 8 on the inner constricted portion 5c and its peripheral portion, and heat-shrink. Etc. are considered.

  In the case housing step S6, the inner metal case 5 on which the elastic member 8 is arranged in the previous step S5 is housed in the bottomed cylindrical outer metal case 6. The outer metal case 6 is made of, for example, aluminum, and an outer pressure valve 6b is formed in advance at the center of the bottom plate 6a. The absorbing member 7 needs to be disposed in the outer metal case 6 before the inner metal case 5 is accommodated.

In the second tightening step S7, as in the first tightening step S4, a disk-shaped jig is pressed near the opening end of the outer metal case 6 to form the outer constricted portion 6c near the opening end, and the elastic member 8 is Tighten (compress). However, in this process, a jig smaller than the first tightening process S4 is used.
When the outer constricted portion 6c is formed, the compressed elastic member 8 is deformed into an appropriate shape that fills the gap between the inner constricted portion 5c and the outer constricted portion 6c, and the airtightness of the space 9 is improved. At the same time, in this step, the opening end of the outer metal case 6 is also bent.

  As mentioned above, although preferable embodiment of the electrolytic capacitor which concerns on this invention, and its manufacturing method has been described, this invention is not limited to said structure.

  For example, in the said embodiment, although the absorption member 7 was arrange | positioned in the space 9 between the inner metal case 5 and the outer metal case 6, this space 9 and the absorption member 7 can be abbreviate | omitted. That is, the present invention can be applied to any double case structure electrolytic capacitor including the inner metal case 5 and the outer metal case 6 and a method of manufacturing the same.

  The position where the inner pressure valve 5b is provided is not limited to the central portion of the bottom plate 5a of the inner metal case 5, and can be changed to any position on the bottom plate 5a. Similarly, the position where the external pressure valve 6b is provided is not limited to the central portion of the bottom plate 6a of the outer metal case 6, and can be changed to any position on the bottom plate 6a.

Moreover, in the said embodiment, although the electrolytic capacitor 1 was manufactured through seven processes (S1-S7), you may provide an inspection process suitably between each process, 1st clamping process S4 and case accommodation process An aging process of the capacitor element 2 may be further provided during S6.
Before the inner metal case 5 is accommodated in the outer metal case 6, if the capacitor element 2 is aged, it is determined whether or not an abnormality such as expansion of the inner metal case 5 caused by the aging has occurred. Can do.

DESCRIPTION OF SYMBOLS 1 Electrolytic capacitor 2 Capacitor element 3 Sealing member 4 Lead 5 Inner metal case 5a Bottom plate 5b Inner pressure valve 5c Inner constriction part 6 Outer metal case 6a Bottom plate 6b Outer pressure valve 6c Outer constriction part 7 Absorbing member 8 Elastic member 9 Space

Claims (5)

A capacitor element, a bottomed cylindrical inner metal case that houses the capacitor element, a bottomed cylindrical outer metal case that covers the inner metal case, and a sealing member that seals the opening of the inner metal case; An electrolytic capacitor comprising a constriction provided near the opening end of the inner metal case and near the opening end of the outer metal case,
An electrolytic capacitor characterized in that an elastic member is sandwiched between a constriction part of the inner metal case and a constriction part of the outer metal case.   The electrolytic capacitor according to claim 1, wherein the elastic member is made of synthetic rubber. An element manufacturing process for manufacturing a capacitor element;
An element housing step of housing the capacitor element in a bottomed cylindrical inner metal case;
A sealing step of sealing the opening of the inner metal case with a sealing member;
A first tightening step of tightening the sealing member by forming a constriction near the opening end of the inner metal case;
An elastic member disposing step of disposing an elastic member on the constricted portion of the inner metal case;
A case housing step of housing the inner metal case after the elastic member is disposed in a bottomed cylindrical outer metal case;
A second tightening step of tightening the elastic member by forming a constricted portion near the opening end of the outer metal case;
An electrolytic capacitor manufacturing method comprising:   The method for manufacturing an electrolytic capacitor according to claim 3, further comprising an aging step of the capacitor element between the first tightening step and the case housing step.   5. The method of manufacturing an electrolytic capacitor according to claim 3, wherein the elastic member is a synthetic rubber.

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