JPH0513289A - Aluminum electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide an aluminum electrolytic capacitor in which driving electrolyte does not flow out at the time of operating an explosion-proof valve. CONSTITUTION:The aluminum electrolytic capacitor comprises a capacitor element 11 impregnated with driving electrolyte, a bottomed cylindrical metal case 12 containing the element 11, a pair of leads 13, 13a extended from the element 11, and a sealing member 14 for sealing the opening of the case 12. Particular gelling agent 19 having properties for gelling the electrolyte is disposed above an explosion-proof valve 15 provided at a ceiling 12a of the case 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum electrolytic capacitor used in electronic equipment.

[0002]

2. Description of the Related Art Generally, in an aluminum electrolytic capacitor, when an overvoltage higher than the rated voltage is applied, the organic solvent constituting the driving electrolyte impregnated in the capacitor element is vaporized due to a temperature rise, and the electrochemical reaction causes an electrochemical reaction. Since hydrogen gas is generated, the internal pressure of the metal case made of aluminum rises. If there is no gas outlet at this time, if the internal pressure of the metal case exceeds the sealing force of the metal case's sealing member, the capacitor element will disengage from the metal case and jump out of the metal case, or the metal case will jump. Very dangerous.

Therefore, in a conventional aluminum electrolytic capacitor, a weak point portion which is a thin portion is usually provided on a top plate portion of a metal case, and when the internal pressure of this metal case rises abnormally, the weak point portion is opened. Since the gas of the organic solvent forming the driving electrolytic solution in the metal case flows out from the open portion to the outside, a large explosion does not occur.

However, according to the above construction, since the driving electrolytic solution is ejected to the outside, there is a problem that the inside of the device in which the electrolytic capacitor is set is contaminated or is mistaken for smoke due to fire.

In order to solve the above problems, an electrolytic capacitor as shown in FIG. 2 has been proposed, as disclosed in, for example, Japanese Utility Model Application Laid-Open No. 1-129819. In the electrolytic capacitor shown in FIG. 2, the top surface portion 2a of the metal case 2 in which the explosion-proof valve 1 is formed is covered with the coating material 3 having the property of absorbing the electrolytic solution and the air permeability. According to this configuration, when the explosion-proof valve 1 is activated in an abnormal condition, the explosion-proof valve 1
Since the driving electrolytic solution ejected from the portion is absorbed by the coating material 3, it does not flow out.

[0006]

However, in the conventional aluminum electrolytic capacitor as shown in FIG. 2, when an overvoltage higher than the rated voltage is applied, a large aluminum electrolytic capacitor having a large amount of driving electrolytic solution is used. In this case, when the explosion-proof valve 1 is activated, a large amount of electrolytic solution vapor and a large amount of high-velocity gas such as hydrogen are ejected at one time, and thus the coating material 3 formed of sponge, felt or the like is ejected. In order to absorb all the driving electrolyte solution, it is necessary to increase the thickness of the covering material 3 or increase the absorption rate of the covering material 3,
In this case, since the air permeability of the covering material 3 is impaired, the covering material 3 arranged on the explosion-proof valve 1 is removed by the ejected gas, or the sealing member for sealing the opening of the metal case 2 is removed. However, there is a problem that the driving electrolyte flows out to the outside.

The present invention has been made to solve the above-mentioned problems, and even when an overpower higher than the rated voltage is applied to a large-sized aluminum electrolytic capacitor having a large amount of driving electrolyte and the explosion-proof valve operates. An object of the present invention is to provide an aluminum electrolytic capacitor in which the driving electrolytic solution does not flow out to the outside.

[0008]

In order to achieve the above object, the present invention provides an aluminum electrolytic capacitor, a capacitor element impregnated with a driving electrolytic solution, and a bottomed cylindrical metal case containing the capacitor element. And a pair of lead wires led out from the capacitor element, and a sealing member for sealing the opening of the metal case, above the explosion-proof valve provided in the top plate of the metal case, the driving electrolytic A granular gelling agent having the property of gelling a liquid is arranged.

[0009]

According to the aluminum electrolytic capacitor having the above structure, the granular gelling agent having the property of gelating the driving electrolytic solution is arranged above the explosion-proof valve provided on the top plate of the metal case. If this aluminum electrolytic capacitor is a large-sized aluminum electrolytic capacitor that has a large amount of driving electrolyte, the explosion-proof valve operates when an overvoltage higher than the rated voltage is applied, and a large amount of driving electrolyte is generated from this explosion-proof valve. A large amount of gas such as hydrogen will be ejected, but since the granular gelling agent is placed above the explosion-proof valve, the gelling amount of electrolyte per unit volume is increased due to the expansion of the surface area of this gelling agent. And the air permeability does not decrease, so that a large amount of the driving electrolyte can be gelled and retained without impairing the air permeability, so that the driving electrolyte does not flow out to the outside. To prevent It is kill things.

[0010]

EXAMPLES Examples of the present invention will be described below.

The basis of the present invention is to dispose a gelling agent having a property of gelling the driving electrolyte solution above the explosion-proof valve provided on the top plate of the metal case. Is not particularly limited, and examples thereof include cellulose, cellulose nitrate, cellulose acetate, hydroxyalkyl cellulose (hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc.), alkyl cellulose (methyl cellulose, ethyl cellulose, etc.), carboxyalkyl cellulose alkali metal salt (sodium carboxy). Cellulose derivatives such as methylcellulose, sodium carboxyethylcellulose, etc., alkali metal salts of alginic acid (sodium alginate, etc.), gelatin, agar, konjak flour, starch, sugar and polysaccharides, proteins Act albumin include those mixed one kind or two or more kinds of these yolk proteins etc.). Other gelling agents include polyvinyl alcohol, polyvinyl alcohol derivatives (formalized polyvinyl alcohol, acetalized polyvinyl alcohol, butyralized polyvinyl alcohol, etc.), polyvinyl ether derivatives (polyvinyl methyl ether, polyvinyl ethyl ether, etc.), polyvinyl acetate. , Vinyl acetate-vinyl alcohol copolymer, vinyl acetate-ethylene copolymer, polyethylene, polypropylene, polyisobutylene, or a mixture or a mixture of two or more thereof.

Preferred of these gelling agents are
It is a cellulose derivative such as an alkali metal salt of cellulose, alkyl cellulose or carboxyalkyl cellulose.

An embodiment of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 11 denotes a capacitor element. This capacitor element 11 has a dielectric oxide film formed on the surface of an anode foil made of a roughened aluminum foil, and the anode foil and the cathode foil are wound together with a separator. It is composed by. Then, the capacitor element 11 is impregnated with a driving electrolytic solution, and
Is mounted in a cylindrical metal case 12 having a bottom and made of aluminum. A pair of lead wires 13 and 13a are led out from the capacitor element 11, and a sealing member 14 seals the open end of the metal case 12. In addition, an explosion-proof valve 15 having a thin weak point is formed on the top plate 12a of the metal case 12. Further, 16 is a bottomed cylindrical holding member, and a plurality of holes 17 are provided in the bottomed portion 16a of this holding member 16, and inside this holding member 16,
A gelling agent holding paper 18 such as a filter paper is inserted through the opening at one end so as to come into contact with the bottomed portion 16a, and the driving electrolytic solution is gelated so as to come into contact with the gelling agent holding paper 18. A granular gelling agent 19 is inserted. Further, a gelling agent holding paper 18a is inserted into one end opening side of the holding member 16 so as to abut the gelling agent 19. Then, the gelling agent 19 is held in the holding member 16 by press-fitting a disc 21 having one hole 20 in the substantially central portion from the opening at one end of the holding member 16.

The holding member 16 holding the gelling agent 19 in this manner is press-fitted from one end opening of a cylindrical fixing member 12b formed integrally with and extending from the top plate 12a side of the metal case 12. In this case, the space 22 is formed between the top plate 12a of the metal case 12 and the circular plate 21 by press-fitting so that the one end opening of the holding member 16 abuts on the top plate 12a of the metal case 12. It is what is formed.
The holding member 16 is press-fitted into the cylindrical fixing member 12b, and then fixed by curling the one end opening of the cylindrical fixing member 12b inward.

The operation of the above arrangement will be described below. When an overvoltage is applied to a large aluminum electrolytic capacitor having a large amount of driving electrolyte, the capacitor element 11 generates heat, and due to this heat, the driving electrolyte is gasified and gas such as hydrogen is generated. And metal case 12
Increase the internal pressure of. Due to this increase in internal pressure, the explosion-proof valve 15 formed on the top plate 12a of the metal case 12 operates,
A large amount of the driving electrolyte solution and a gas such as hydrogen are ejected from the explosion-proof valve 15 into the space 22. Then, a part of the gasified driving electrolytic solution hits the disk 21 and is cooled and liquefied, and is accumulated in the space 21. On the other hand, the gasified driving electrolyte that passes through the holes 20 provided in the circular plate 21 is gelled by the gelling agent 19, so that it does not flow out to the outside, and gas such as hydrogen is gelled. Since the agent 19 is granular, it passes through the granular gelling agent 19 without being blocked by the gelling agent 19, so that the driving electrolytic solution does not flow out to the outside.

[0016]

As is clear from the description of the above embodiment,
The aluminum electrolytic capacitor of the present invention has a granular gelling agent having a property of gelating the driving electrolyte solution disposed above the explosion-proof valve provided on the top plate of the metal case. In the case of a large aluminum electrolytic capacitor that has a large amount of driving electrolyte, if an overvoltage higher than the rating is applied, the explosion-proof valve will operate, and a large amount of driving electrolyte and a large amount of hydrogen etc. However, since the granular gelling agent is placed above the explosion-proof valve, the increase in the surface area of this gelling agent causes an increase in the amount of electrolytic solution gelation per unit area. With being peeled off,
Since the large amount of driving electrolyte can be gelled and retained without impairing the air permeability without impairing the air permeability, it is possible to prevent the driving electrolyte from flowing out to the outside. Is.

[Brief description of drawings]

FIG. 1 is a sectional view of an aluminum electrolytic capacitor showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a conventional aluminum electrolytic capacitor.

[Explanation of symbols]

11 Capacitor element 12 metal cases 12a Top plate part 13,13a a pair of lead wires 14 Sealing member 15 Explosion-proof valve 19 Gelling agent

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Kabahara             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd.

Claims (3)

[Claims] 1. A capacitor element impregnated with a driving electrolytic solution, a bottomed cylindrical metal case containing the capacitor element, a pair of lead wires led out from the capacitor element, and an opening of the metal case. A sealing member for sealing the portion, and a granular gelling agent having a property of gelating the driving electrolyte is disposed above the explosion-proof valve provided in the top plate portion of the metal case. Aluminum electrolytic capacitor. 2. The gelling agent is cellulose, cellulose nitrate, cellulose acetate, hydroxyalkyl cellulose,
Alkyl cellulose, cellulose derivative consisting of alkali metal salt of carboxyalkyl cellulose, alkali metal salt of alginic acid, gelatin, agar, konjak flour, starch, sugar or polysaccharide, protein Any one kind or a mixture of two or more kinds thereof. Claim 1 consisting of
Aluminum electrolytic capacitor described. 3. A gelling agent is polyvinyl alcohol, polyvinyl alcohol derivative, polyvinyl ether derivative,
The polyvinyl acetate, vinyl acetate-vinyl alcohol copolymer, vinyl acetate-ethylene copolymer, polyethylene, polypropylene, polyisobutylene, or a copolymer or mixture of two or more thereof. Aluminum electrolytic capacitor.