JP2011216611A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent jetting of an evaporated electrolyte from a pressure valve even if a pressure valve of an electrolytic capacitor is opened.SOLUTION: A pressure valve 14 is formed on a bottom face, and an armored case 12 including a projecting collar part 12a is provided to surround an outer periphery of the bottom face. In a prescribed space formed by the bottom face of the armored case 12 and the collar part 12a, a metallic holding member 20 storing an absorbent for the electrolyte and the like and formed with a pressure valve 14a on a bottom face is stored, and the holding member 20 is fixed by bending a tip of the collar part. As a result, evaporated electrolyte discharged by opening of the pressure valve 14 remains inside the holding member 20 once, and the absorbent 22 for the electrolyte and the like can sufficiently take in the evaporated electrolyte, thus preventing the electrolyte from jetting outside the electrolytic capacitor.

Description

  The present invention relates to an electrolytic capacitor used in an electronic device.

  In general, when an overvoltage higher than the rated voltage is applied to an electrolytic capacitor, the organic solvent constituting the electrolytic solution impregnated in the capacitor element is vaporized due to a temperature rise, and hydrogen gas is generated due to an electrochemical reaction. The internal pressure of the outer case made of aluminum increases. At this time, if there is no gas discharge port, if the internal pressure of the outer case exceeds the sealing force by the sealing member of the outer case, the sealing member will come off the outer case and jump out of the outer case, or the outer case will jump off. Can be very dangerous.

  Therefore, in a conventional aluminum electrolytic capacitor, a weak point portion consisting of a thin portion is usually provided on the bottom surface of the outer case, and when the internal pressure of the outer case rises abnormally, the weak point portion is opened and Since the vaporized electrolyte and hydrogen gas are released to the outside, a large explosion does not occur.

  However, according to the above configuration, there is a problem that the vaporized electrolyte discharged to the outside contaminates the inside of the device in which the electrolytic capacitor is set and is mistaken for smoke due to fire.

  In order to solve the above problems, an electrolytic capacitor as described in, for example, Japanese Utility Model Laid-Open No. 01-129819 (Patent Document 1) has been proposed. In the electrolytic capacitor disclosed in this publication, the bottom surface of the outer case in which the pressure release mechanism is formed is covered with a covering material (sponge or felt material) that absorbs electrolyte and has air permeability. According to this configuration, when the pressure release mechanism is activated at the time of abnormality, the electrolytic solution is absorbed by the covering material, and thus is not released to the outside.

  Further, as described in Japanese Patent Application Laid-Open No. 5-13289 (Patent Document 2), a capacitor element impregnated with an electrolytic solution, a bottomed cylindrical outer case containing the capacitor element, and a capacitor element A pair of derived lead wires and a sealing member that seals the opening of the outer case are provided, and a granular gelling agent having a property of gelling the electrolyte is inserted into the low and low cylindrical holding member. An electrolytic capacitor in which the gelling agent is disposed above a pressure release mechanism provided on the bottom surface of the outer case has also been proposed.

  According to the electrolytic capacitor described in Patent Document 2, a granular gelling agent having a property of gelling an electrolytic solution is disposed above the pressure release mechanism provided on the bottom surface of the outer case. In the case of a large aluminum electrolytic capacitor having a large amount of electrolyte, the pressure release mechanism is activated when an overvoltage higher than the rated voltage is applied. Hydrogen gas is ejected, but since the granular gelling agent is arranged above the pressure release mechanism, the gelling amount of the electrolyte per unit volume is increased due to the expansion of the surface area of the gelling agent. In addition to being peeled off, there is no decrease in air permeability, and this allows gelling and holding of a large amount of electrolyte without impairing air permeability, thus preventing discharge of the electrolyte to the outside. It is.

Japanese Utility Model Publication No. 01-1229819 JP 05-13289 A

  The electrolytic capacitor disclosed in the above-described patent document has a function of preventing the electrolyte solution from being released to the outside of the outer case by the electrolyte solution absorbent when the pressure release mechanism is opened. Normally, when the pressure release mechanism is opened, the inside of the outer case is at a high internal pressure, so that hydrogen gas, vaporized electrolyte, and the like are released from the pressure release mechanism vigorously. For this reason, it passes through absorbents, such as electrolyte solution, and is easy to be ejected outside. In such a state, there is a possibility that the electrolyte absorbing function cannot be sufficiently exhibited.

  In view of the above problems, the present invention increases the absorption efficiency of the electrolytic solution vaporized by an absorbent such as an electrolytic solution, so that the electrolytic solution is released from the pressure releasing mechanism even when the pressure releasing mechanism of the electrolytic capacitor is opened. The object is to provide an electrolytic capacitor that can be prevented.

  The electrolytic capacitor of the present invention contains a capacitor element in which an anode foil and a cathode foil are wound or laminated through a separator and impregnated with an electrolytic solution in a low and low cylindrical outer case, and is placed on the bottom surface of the outer case. The pressure release mechanism is formed, and has a flange portion protruding so as to surround the outer periphery of the bottom surface, and an absorbent such as an electrolyte solution is stored in a predetermined space formed by the bottom surface and the flange portion of the outer case. In addition, a holding member having a pressure release mechanism formed on the bottom surface is accommodated, and the holding case is fixed by bending the front end of the collar portion.

  According to this, when the internal pressure in the outer case increases and the pressure release mechanism is opened, the vaporized electrolyte or the like passes through the pressure release mechanism and enters the holding member. The predetermined space formed by the bottom surface and the collar portion of the outer case is closed by the holding member, and the evaporated electrolyte etc. once stays in the holding member. The evaporated electrolyte is taken in. Further, when the internal pressure in the holding member rises due to the generation of hydrogen gas or the like, the pressure release mechanism formed in the holding member is released, but the vaporized electrolyte is taken into the absorbent such as the electrolyte, so that the vaporization The electrolyte is not released to the outside.

  Further, the holding member is made of a metal material. According to this, since the holding member is made of a metal material, even if the vaporized electrolyte or the like is released vigorously, the holding member does not deform and the vaporized electrolyte or the like is retained. Can be kept inside.

  Further, the absorbent such as the electrolytic solution is characterized in that a thin plate is attached to the outer surface of the pressure release mechanism formed on the bottom surface of the outer case. According to this, since a thin plate is attached to the outer surface of the pressure release mechanism, the vaporized electrolyte solution (other hydrogen gas etc.) released by the release of the pressure release mechanism is surrounded by the periphery of the thin plate. And is dispersed in an absorbent such as an electrolytic solution. Therefore, the absorption efficiency of the vaporized electrolytic solution and the like by the absorbent such as the electrolytic solution can be increased, and the release of the electrolytic solution from the pressure release mechanism can be prevented.

  Further, the outer case is characterized in that the connecting portion between the bottom surface and the collar portion is inclined from the bottom surface to the collar portion. According to this, even when the strength of the bottom surface and the flange portion is increased and the pressure release mechanism is released and the evaporated electrolyte or the like is released vigorously, there is a gap between the holding member and the bottom surface of the outer case. And the like, and the release of the electrolytic solution from the pressure release mechanism can be prevented.

  Further, the absorbent such as the electrolytic solution is cyclodextrin. According to this, since cyclodextrin is excellent in the function of absorbing the vaporized electrolyte, the amount of the absorbent such as the electrolyte can be reduced and thinned, and the electrolytic capacitor can be downsized.

  Further, the mounting amount of the absorbent such as the electrolytic solution is 0.3 or more when the amount of the electrolytic solution contained in the electrolytic capacitor is 1. According to this, the weight ratio when the amount of the electrolyte contained in the electrolytic capacitor is 1, and when 0.3 or more of the absorbent such as the electrolyte is mounted, it flows out as smoke to the outside of the electrolytic capacitor. Can be surely prevented.

  As described above, according to the present invention, even when the internal pressure of the electrolytic capacitor is increased, the pressure release mechanism of the electrolytic capacitor is opened, and the vaporized electrolytic solution is released, the absorption efficiency of the vaporized electrolytic solution by the absorbent such as the electrolytic solution is increased. The vaporized electrolytic solution or the like is not released to the outside.

It is sectional drawing which shows the Example of the electrolytic capacitor of this invention.

  Hereinafter, embodiments of the present invention will be described.

  The present invention provides a pressure release mechanism on the bottom surface of the exterior case, and also has a flange portion protruding so as to surround the outer periphery of the bottom surface, and an electrolyte solution in a predetermined space formed by the bottom surface and the flange portion of the exterior case. And the like, and a holding member having a pressure release mechanism formed on the bottom surface is accommodated, and the holding member is fixed by bending the front end of the collar portion.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of the electrolytic capacitor of the present invention. Capacitor element 11 is formed by winding an anode foil having a dielectric oxide film formed by roughening an aluminum foil by etching, and a cathode foil having a roughened aluminum foil by etching together with a separator. ing. A multilayer capacitor element in which an anode foil and a cathode foil are laminated via a separator may be used. A lead terminal 13 for external lead is connected to the anode foil and the cathode foil, respectively, and is led out from one end face of the wound capacitor element 11.

  The capacitor element 11 is impregnated with an electrolytic solution, and the capacitor element 11 is accommodated in a bottomed cylindrical outer case 12 made of aluminum. A pressure valve 14 (pressure release mechanism) is formed on the bottom surface of the exterior case 12 to form a mechanically fragile portion by forming a groove radially from the center of the bottom surface of the exterior case 12. The pressure release mechanism referred to in the present invention is not limited to the pressure valve 14 provided in the outer case 12, and a filter such as a rubber that provides a through hole in the outer case 12 and closes the through hole is also available. Can be mentioned.

  A sealing member 15 is accommodated in the opening end of the outer case 12. A pair of external terminals 13 penetrates the sealing member 15 and is led out of the sealing member 15. Further, the sealing member 15 is fixed by curling the opening end of the outer case 12, and seals the electrolytic capacitor.

  Further, an absorbent 22 such as an electrolytic solution is disposed outside the pressure valve 14 on the bottom surface of the outer case 12. As a means for disposing the absorbent 22 such as an electrolytic solution outside the pressure valve 14, a bottomed cylindrical holding member 20 made of metal is prepared, and the absorbent 22 such as an electrolytic solution is filled in the holding member 20. Then, it is disposed on the bottom surface of the outer case 12.

  More specifically, a flange 12 a that protrudes from the bottom surface of the outer case 12 so as to surround the outer case 12 is formed, and a storage space is formed by the flange 12 a and the bottom surface of the outer case 12. The holding member 20 containing the absorbent 22 such as the electrolytic solution is stored in the storage space, and the holding member 20 is fixed, so that the absorbent 22 such as the electrolytic solution is attached to the exterior case 12.

  The holding member 20 is made of a bottomed cylindrical metal or the like having an outer shape that covers a storage space provided on the bottom surface of the exterior case, and an absorbent 22 such as an electrolytic solution is stored in the internal space. The absorbent 22 such as an electrolytic solution is often composed of powder or the like. Therefore, filter members 23 and 24 for preventing the electrolyte from being dropped are arranged on both surfaces of the absorbent 22 such as an electrolytic solution, and the electrolytic solution or the like. The absorbent body 22 is sandwiched between the filter members 23 and 24 to form a laminate structure. A pressure valve 14a is formed on the bottom surface of the holding member 20 to form a kerf and becomes a mechanically fragile portion, and is arranged so that the filter 23 of the laminate is in contact with the bottom surface side of the holding member 20. An absorbent 22 such as an electrolytic solution is accommodated in the holding member 20. A thin plate 25 is attached to the outer surface of the filter member 24 with an adhesive or the like. The filter 20 is placed at a position corresponding to the pressure valve 14 provided in the storage space provided on the bottom surface side of the exterior case 12 with the holding member 20 storing the laminate of the absorbent 22 such as the electrolyte solution. The laminated body is arranged and accommodated so that the thin plate 25 attached to the member 24 comes, and the tip of the flange portion 12a is brought into contact with the bottom surface of the outer case 12 by curling, so that the electrolysis is performed. The laminated body of absorbents 22, such as a liquid, is fixed. At this time, the opening end of the holding member 20 is pressed against the bottom surface of the outer case 12 and is brought into close contact therewith. In addition, as the thin plate 25 affixed on the filter member 24, metal foil, a resin plate, etc. are mentioned. The thin plate 25 is a circular thin plate having a thickness of about 50 μm. As the filter members 23 and 24, a thin paper member made of cellulose fiber, an activated carbon sheet, a porous member having a through hole in a film, or the like is used.

  Various materials are used as the absorbent 22 such as an electrolytic solution. For example, paper such as filter paper, non-woven fabric such as polyester and polyamide, sponge, felt and other substances that can absorb vaporized electrolyte (synthetic polymer), gelling agent that absorbs electrolyte by gelation, etc. Can be mentioned. Among the absorbents 22 such as the electrolytic solution, it is preferable to use cyclodextrin.

  Cyclodextrins are also referred to as cyclic oligosaccharides, and form both ends of oligosaccharides formed by connecting glucose and forming a ring. Of these, 6 glucoses are linked to form a ring of “α-cyclodextrin”, 7 of which are linked to form a ring of “β-cyclodextrin”, and 8 are connected to form a tube Is called “γ-cyclodextrin”.

  And the inside of the cyclic structure of cyclodextrin is a void | hole of the magnitude | size which can include other relatively small molecules. The inner diameter of the pores is about 0.45-0.6 nm for α-cyclodextrin, 0.6-0.8 nm for β-cyclodextrin, and about 0.8-0.95 nm for γ-cyclodextrin. Cyclodextrins are said to have lipophilicity in the pores and hydrophilicity in the outside.

  The reason why such a cyclodextrin functions as the absorbent 22 such as an electrolytic solution is thought to be because the vaporized electrolytic solution component is included in the pores of the cyclodextrin.

  Most preferred among these cyclodextrins is β-cyclodextrin. If cyclodextrin is used as the absorbent 22 such as an electrolytic solution, it is effective in that the vaporized electrolytic solution can be prevented from being released to the outside of the electrolytic capacitor even when the pressure release mechanism is opened. However, in particular, when β-cyclodextrin was used as the absorbent 22 such as an electrolytic solution, the effect of absorbing the electrolytic solution was obtained even when the amount was small. This is a good anti-smoke measure.

  The reason why β-cyclodextrin is suitable as the absorbent 22 such as an electrolytic solution is not clear, but it is considered that the size of the pores has an influence. In other words, the α-form, β-form and γ-form of cyclodextrin are presumed to be suitable for enclosing the vaporized electrolyte solution, although the sizes of the pores are different. In addition, α-cyclodextrin and γ-cyclodextrin are water-soluble, but β-cyclodextrin is considered to be related to the poor water-solubility. The capacitor element and the electrolytic solution may contain moisture, and when the pressure release mechanism is released, the moisture is also released as water vapor. Since β-cyclodextrin is sparingly water-soluble, it is considered that the absorption function of the electrolytic solution is sufficiently exhibited because it is difficult to cause a phenomenon such as dissolution into water vapor and release to the outside of the electrolytic capacitor together with water vapor.

  In such an electrolytic capacitor 10, when the internal pressure in the outer case 12 rises and the pressure valve 14 is opened, the evaporated electrolyte or the like passes through the pressure valve 14 and enters the holding member 20. The predetermined space formed by the bottom surface of the outer case 12 and the flange portion 12a is closed by the holding member 20, and the evaporated electrolyte or the like once stays in the holding member 20. At this time, the evaporated electrolyte solution is taken in by the absorbent 22 such as an electrolyte solution. Further, when the internal pressure in the holding member 20 rises due to generation of hydrogen gas or the like, the pressure valve 14a provided in the holding member 20 is opened, and the evaporated electrolyte solution is taken in the absorbent 22 such as an electrolyte solution. Although hydrogen gas is released to the outside, the vaporized electrolyte is not released to the outside because it is taken into the absorbent 22 such as the electrolyte. In addition, the holding member 20 is made of a metal such as aluminum, so that even when the evaporated electrolyte solution or the like is released vigorously, the holding member 20 is not deformed and the evaporated electrolyte solution or the like is used. It can be fastened in the holding member 20.

  Further, since the connecting portion 16 between the bottom surface of the outer case 12 and the flange portion 12a is inclined from the bottom surface to the flange portion, the strength of the bottom surface of the outer case 12 and the flange portion 12a is increased, and the pressure is increased. Even when the valve 14a is opened and the evaporated electrolyte or the like is released vigorously, a gap or the like is not generated between the holding member 20 and the bottom surface of the outer case 12, and the electrolyte is discharged from the pressure valve 14. Can be prevented.

  Here, the function of the thin plate 25 attached to the filter member 24 will be described. The vaporized electrolyte discharged from the pressure valve 14 is diffused around the thin plate 25 and dispersed in the filter member 24. Normally, when the pressure valve 14 is opened, the inside of the outer case 12 has a high internal pressure, so that hydrogen gas and the vaporized electrolyte solution are released from the pressure valve 14 vigorously. When this thin plate 25 is not installed, hydrogen gas or the vaporized electrolyte easily breaks through the absorbent members 22 such as the filter members 23 and 24 and the electrolyte, and is easily ejected to the outside. In such a state, there is a possibility that the absorbent 22 such as the electrolytic solution at a position deviating from the linear shape cannot exhibit the function of absorbing the vaporized electrolytic solution. Therefore, it is preferable to dispose the thin plate 25 of the filter member 24 so as to cover the pressure valve 14, and to diffuse the vaporized electrolyte or the like discharged from the pressure valve 14 around the thin plate 25. A through hole may be provided near the outer peripheral edge of the thin plate 25 to further disperse the vaporized electrolyte. Also, the filter member 24 may have a function of dispersing the vaporized electrolyte by appropriately setting the surface state and density of the filter member 24 in addition to the function of holding the absorbent 22 such as the electrolyte. Considering this dispersion function, the filter member 24 may be set thicker than the filter member 23.

  Next, the loading amount of the absorbent such as the electrolytic solution will be described. The absorption effect of the electrolytic solution varies depending on the amount of the electrolytic solution contained in the electrolytic capacitor. If the amount of absorbent, such as electrolyte, is small relative to the amount of electrolyte, the amount of electrolyte that is vaporized when the pressure release mechanism is released decreases, and the vaporized electrolyte flows out and can be visually recognized. End up with smoke. Therefore, when the amount of the electrolytic solution and the amount of the absorbent such as the electrolytic solution were studied, the weight ratio when the amount of the electrolytic solution contained in the electrolytic capacitor was 1, and the absorbent of the electrolytic solution was 0.3 or more. It was found that it was possible to prevent smoke from flowing out of the electrolytic capacitor. Further, it has been found that the amount of the absorbent such as the electrolytic solution can generally obtain the absorbing effect of the electrolytic solution both in the initial stage of the electrolytic capacitor and in the end-of-life state.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, in the embodiment, thin plate-like filter members 23 and 24 are provided and sandwiched on both surfaces of an absorbent 22 such as an electrolyte solution. However, the present invention is not limited thereto, and a bag-like filter member is used for the electrolyte solution. You may make it wrap an absorbent.

DESCRIPTION OF SYMBOLS 10 Electrolytic capacitor 11 Capacitor element 12 Exterior case 12a Eaves part 13 External terminal 14 Pressure valve 14a Pressure valve 15 Sealing member 16 Connection part 20 Holding member 22 Absorbent 23 such as electrolyte solution Filter member 24 Filter member 25 Thin plate

Claims (6)

  A capacitor element impregnated with an electrolytic solution obtained by winding or laminating an anode foil and a cathode foil via a separator is housed in a low and low cylindrical outer case, and a pressure release mechanism is formed on the bottom surface of the outer case. And a flange that protrudes so as to surround the outer periphery of the bottom surface, and in a predetermined space formed by the bottom surface and the flange of the exterior case, an absorbent such as an electrolyte is accommodated and a pressure release mechanism is provided on the bottom surface. An electrolytic capacitor in which the formed holding member is stored and the holding case is fixed by bending the tip of the collar.   The electrolytic capacitor according to claim 1, wherein the holding member is made of a metal material.   3. The electrolytic capacitor according to claim 1, wherein a thin plate is attached to an external surface of a pressure release mechanism formed on a bottom surface of the outer case in the absorbent such as the electrolytic solution.   4. The electrolytic capacitor according to claim 1, wherein a connecting portion between the bottom surface and the flange portion of the outer case is inclined from the bottom surface to the flange portion.   The electrolytic capacitor according to claim 1, wherein the absorbent such as the electrolytic solution contains cyclodextrin. The electrolytic capacitor according to any one of claims 1 to 5, wherein a loading amount of the absorbent such as the electrolytic solution is 0.3 or more in a weight ratio where the amount of the electrolytic solution contained in the electrolytic capacitor is 1.

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