JP2010109024A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor having a double case structure such that a capacitor body containing a capacitor element in an inner case is stored in an outer case, wherein an electrolyte is prevented from flowing out during valve operation, by the simple and inexpensive structure. <P>SOLUTION: The electrolytic capacitor has the double case structure such that the capacitor body 1 having the capacitor element 11 impregnated with the electrolyte, the bottomed cylindrical inner case 13 housing the capacitor element 11 and where an explosion-proof valve 131 is formed, and a sealing material 15 for sealing an opening of the inner case 13 is housed in the outer case 5 having a space larger than the capacity of the inner case 13 inside, and the opening of the outer case 5 is sealed with the sealing material 7. The electrolytic capacitor has a fixture 3 for fixing the capacitor body 1 to the outer case 5 at an inner bottom portion of the outer case 5, and the fixture 3 is formed of a porous material or a gelation material for making the electrolyte gel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor having a double case structure in which a capacitor body having a capacitor element housed in an inner case is housed in an outer case.

  Generally, an electrolytic capacitor is formed by winding an electrode foil made of aluminum and a separator to form a capacitor element. The capacitor element is impregnated with an electrolytic solution, and the impregnated capacitor element is housed in an aluminum case and sealed. It is configured by sealing with a material.

  When a voltage higher than the rating or a current exceeding the rated ripple current is applied to the electrolytic capacitor, the capacitor element generates heat and the electrolyte is gasified to increase the internal pressure of the case. And when this internal pressure exceeds the sealing force of a sealing material, a capacitor | condenser element may remove | deviate from a case.

  For this reason, such an electrolytic capacitor is usually provided with an explosion-proof valve (weak body) in the case. When the internal pressure of the case rises abnormally, the valve is opened and the gas (gaseous electrolyte) is discharged to the outside. Released. However, there is a problem that the inside of the device on which the electrolytic capacitor is mounted is contaminated by the released gas, or the gaseous electrolyte is indistinguishable from smoke caused by ignition.

  Therefore, a technique for preventing the electrolyte from flowing out to the outside when the explosion-proof valve is operated has been proposed. For example, in the electrolytic capacitor described in Patent Document 1, a capacitor element is housed in a metal case, and a pair of fuse wires are connected to the ends of a pair of lead wires led out from the capacitor element. In addition, a sealing member is disposed in the opening of the metal case, and an explosion-proof valve is formed in the sealing part of the metal case. A separate exterior case is disposed outside the metal case, and an opening of the exterior case is sealed by a sealing member. When an overvoltage or the like is applied to the electrolytic capacitor, the internal pressure of the metal case is increased by the gaseous electrolytic solution, the explosion-proof valve is activated, and the generated gas is ejected. Since the generated gas is jetted into the upper space between the metal case and the outer case, the internal electrolytic capacitor moves to the bottom side together with the metal case due to the pressure in the upper space, and the fuse wire is cut accordingly.

  Moreover, in the electrolytic capacitor described in Patent Document 2, a capacitor element is housed in a metal case, and an explosion-proof valve is formed on the top plate portion of the metal case. Also, a bottomed cylindrical holding member is arranged on the top of the capacitor element, and the gelling agent holding paper is inserted into the bottomed portion in the holding member, and the granular gelling agent is brought into contact with the gelling agent holding paper. And the gelling agent is held in the holding member by press-fitting a disc having a hole in the center. Thereby, a space part is formed between the top plate part of the metal case and the disk. In this electrolytic capacitor, when an overvoltage is applied, the internal pressure of the metal case is increased by the gaseous electrolyte, the explosion-proof valve is activated, and the gas is ejected into the space. A part of the gaseous electrolytic solution hits the disk and is cooled and liquefied, and accumulates in the space. On the other hand, the gas that has passed through the holes provided in the disk is gelled by the gelling agent, and is prevented from flowing out.

JP 2003-31447 A JP-A-5-13289

  However, the electrolytic capacitor described in Patent Document 1 requires a space for moving the internal electrolytic capacitor in addition to the space (upper space) for diffusing the released gas in order to cut the fuse wire.・ It will be against the request of low profile. Further, even in the electrolytic capacitor described in Patent Document 2, since the space portion and the accommodating portion for accommodating the gelling agent are formed above the capacitor element, it is difficult to reduce the size and height of the product.

  In addition, in the electrolytic capacitor described in Patent Document 1, it is necessary to newly connect a pair of fuse wires and a pair of lead wires using a pair of fuse wires. In addition to the agent, a member such as a holding member for holding the gelling agent, a gelling agent holding paper, and a disk is required, which is mechanically complicated and disadvantageous in terms of manufacturing and cost.

  The present invention has been made in view of the above problems, and in a double case structure electrolytic capacitor in which a capacitor body having a capacitor element housed in an inner case is housed in an outer case, it is a simple and inexpensive structure, and at the time of valve operation. The purpose is to prevent the electrolyte from flowing out.

  The present invention includes a capacitor element impregnated with an electrolyte, a bottomed cylindrical inner case in which the capacitor element is housed and formed with a weak body portion, and an inner sealing material that seals an opening of the inner case. A capacitor case having a space larger than the volume of the inner case is accommodated in the outer case, and is an electrolytic capacitor having a double case structure in which an opening of the outer case is sealed with an outer sealing material. A fixing tool for fixing the capacitor main body to the outer case is provided on the inner bottom portion, and the fixing tool is formed of a material that promotes degasification of the gaseous electrolyte ejected from the weak body portion. .

  In the invention thus configured, the capacitor main body (capacitor element is housed in the inner case and sealed with the inner sealing member) is fixed to the outer case by the fixture provided on the inner bottom of the outer case. . Here, the fixture is formed of a material that promotes degasification of the gaseous electrolyte solution ejected from the weak body. Therefore, when an abnormal load such as overvoltage is applied to the electrolytic capacitor and the weak part ruptures (valve operation), the gasified electrolyte (gaseous electrolyte) comes into contact with the fixture, and the gaseous electrolyte Is promoted to be non-gaseous. As a result, the non-gaseous electrolyte is collected between the inner case and the outer case and is held in the outer case. This prevents the electrolyte from flowing out (outside the outer case). As described above, according to the present invention, the fixture for fixing the capacitor body to the exterior case also has a function of preventing the electrolyte from flowing out to the outside. The outflow of the liquid to the outside can be prevented.

  Here, the fixture is preferably formed of a porous material or a material containing a gelling agent that gels the electrolyte. When the fixture is made of a porous material, the gaseous electrolyte that comes into contact with the fixture made of the porous material is efficiently liquefied, and the liquefied electrolyte accumulates between the inner case and the outer case and is discharged to the outside. The electrolyte is prevented from flowing out. Further, when the fixture is made of a material containing a gelling agent, the gaseous electrolyte solution is gelled, the gel electrolyte solution is held in the outer case, and the electrolyte solution is prevented from flowing out to the outside.

  Further, in the electrolytic capacitor in which the weak body portion is formed on the bottom surface of the inner case, it is preferable that the fixture is formed in an annular shape surrounding the bottom surface of the inner case so that the weak body portion faces the inner bottom surface of the outer case. According to this structure, when a weak body part bursts (a valve act | operates), a fixture does not prevent the valve opening. In addition, since the fixture is arranged so as to surround the weak body part in the vicinity of the weak body part, the gaseous electrolytic solution is quickly made non-gaseous without leakage, the electrolytic solution is held in the outer case, It is possible to reliably prevent the electrolyte solution from flowing out.

  According to the present invention, it is possible to prevent the electrolyte from flowing out to the outside during valve operation with a simple and inexpensive structure.

<One Embodiment>
FIG. 1 is a diagram showing an embodiment of an electrolytic capacitor according to the present invention. The electrolytic capacitor is housed in an outer case 5 in a state where the capacitor body 1 is fixed by a fixture 3, and the outer case 5 is sealed with a sealing material 7. The capacitor body 1 includes a capacitor element 11 impregnated with an electrolytic solution, an inner case 13 that houses the capacitor element 11, and a sealing material 15 that seals an opening of the inner case 13. Thus, in this embodiment, the sealing material 7 functions as the “external sealing material” of the present invention, and the sealing material 15 functions as the “internal sealing material” of the present invention.

  The capacitor element 11 is configured by winding an anode foil formed by forming a dielectric oxide film on the surface of a roughened aluminum foil (electrode foil) and a cathode foil via a separator. The capacitor element 11 is impregnated with an electrolytic solution (driving electrolytic solution) and stored in the inner case 13. The inner case 13 is made of a bottomed cylindrical case made of aluminum, and an explosion-proof valve 131 (corresponding to the “weak body” of the present invention) made of a concave groove is formed outside the bottom surface. A pair of lead wires 12 extend from the capacitor element 11, and the opening of the inner case 13 is sealed with a sealing material 15. The sealing material 15 is formed of an elastic member in order to maintain airtightness in the inner case 13.

  The outer case 5 has a space larger than the volume of the inner case 13 inside, and when the capacitor body 1 is stored in the outer case 5, a predetermined gap is formed between the outer side surface of the inner case 13 and the inner side surface of the outer case 5. An annular space (a space S3 to be described later) is formed by being spaced apart by an interval. A fixing tool 3 is disposed on the inner bottom of the outer case 5, and the inner case 13 is fixed to the outer case 5 by the fixing tool 3. The opening of the outer case 5 is sealed by the sealing material 7, and the airtightness in the outer case 5 is maintained. More specifically, in a state where the fixture 3 arranged at the inner bottom portion of the outer case 5 and the bottom portion of the inner case 13 (the edge portion of the circular case bottom surface and the bottom surface side portion of the case side surface) are engaged. The outer case 5 is sealed by the sealing material 7 while the capacitor body 1 (the tightening portion at the opening end of the inner case 13) is in contact with the sealing material 7. Similarly to the sealing material 15, the sealing material 7 is formed of an elastic member.

  The sealing material 7 and the sealing material 15 are sealed and their centers are located on the same axis (cylindrical axis of the inner case 13 and the outer case 5), and the lead insertion hole 7a of the sealing material 7 and the lead insertion of the sealing material 15 The holes 15a are arranged in a matched state. As a result, the pair of lead wires 12 extending from the capacitor element 11 are led out through the lead insertion hole 7a of the sealing material 15 and the lead insertion hole 15a of the sealing material 15 linearly.

  FIG. 2 is a view showing the structure of a fixture provided in the electrolytic capacitor shown in FIG. Specifically, FIG. 5A is a top view of the fixture viewed from above, FIG. 5B is a side view of the fixture, FIG. 10C is a bottom view of the fixture viewed from below, and FIG. FIG. 4D is a cross-sectional view taken along the line AA ′ shown in FIG. The fixture 3 includes an annular part 31 formed in an annular shape and projecting parts 32 provided at four locations on the outer periphery of the annular part 31. The annular portion 31 and the protruding portion 32 are integrally formed. The four projecting portions 32 are provided at equal intervals (90-degree intervals) with respect to the center of the annular portion 32.

  The outer peripheral surface 32a of each protrusion 32 is formed along the inner wall surface of the exterior case 5, and the diameter of a virtual circle formed by virtually connecting the outer peripheral surfaces 32a of each protrusion 32 to each other is It substantially coincides with the inner diameter of the case 5. In addition, a virtual circle (the annular portion 31 of the annular portion 31) is formed by virtually connecting the upper inner peripheral surfaces 32 b on the upper side (opening side of the exterior case 5) with respect to the annular portion 31 of each projecting portion 32. The diameter of the outer circumference circle substantially matches the inner diameter of the inner case 13. Further, the annular portion 31 is formed in a flat plate shape, and an upper surface 31 a (a surface facing the case opening side) is a contact surface capable of contacting the bottom edge of the inner case 13.

  According to such a configuration, when the capacitor main body 1 is housed in the outer case 5 and sealed with the sealing material 7, the bottom edge of the inner case 13 abuts on the upper surface of the annular portion 31, The capacitor main body 1 is securely held by the fixture 3 because the bottom side surface of the case 13 and the upper inner peripheral surface 32 b of each protrusion 31 come into contact with each other.

  On the other hand, each protrusion 32 extends to the lower side (the bottom surface side of the outer case 5), and the tip thereof abuts on the inner bottom surface edge of the outer case 5. As a result, a space S1 having a predetermined volume is formed between the capacitor body 1 and the inner bottom surface of the outer case 5 (hereinafter, the space formed in this way is referred to as a “bottom surface side space”). The lower inner peripheral surface 32c on the lower side (the bottom surface side of the exterior case 5) with respect to the annular portion 31 of each projecting portion 32 is positioned on the radially outer side with respect to the upper inner peripheral surface 32b, and the bottom surface side space S1. The expansion of the volume is planned.

  Here, the fixture 3 is formed in an annular shape that surrounds the bottom surface of the inner case 13 so that the explosion-proof valve 131 faces the inner bottom surface of the outer case 5, so that the opening is fixed when the explosion-proof valve 131 operates. The tool 3 is not hindered. In addition, when the explosion-proof valve 131 is operated, the gasified electrolytic solution (gaseous electrolytic solution) ejected from the explosion-proof valve 131 can be diffused into the bottom surface side space S1. From such a viewpoint, it is preferable that the diameter of the inner circumferential circle of the annular portion 31 is formed larger than the size of the explosion-proof valve 131.

  The fixture 3 is formed of a porous material. For this reason, liquefaction of the gaseous electrolyte solution that has contacted the fixture 3 made of a porous material is promoted, and the liquefied electrolyte solution is accumulated between the inner case 13 and the outer case 5 to the outside (outer case 5). The electrolyte is prevented from flowing out. The material of the fixture 3 is not particularly limited as long as it is resistant to heat and electrolyte and has high workability. For example, glass fiber, zeolite, alumina, activated carbon, silica gel, porous ceramic, porous high Molecule, porous sintered metal, flame retardant paper, flame retardant nonwoven fabric, etc. are used.

  The gaseous electrolyte ejected from the explosion-proof valve 131 is diffused into the bottom surface side space S1 and comes into contact with the fixture 3 to be liquefied. Here, since the protruding portion 32 of the fixture 3 protrudes radially outward with respect to the annular portion 31, a gap space S 2 around the annular portion 31 sandwiched between the adjacent protruding portions 32 is interposed. A bottom surface side space S1 and a space S3 formed around the side surface of the inner case 13 (a space formed so as to surround the inner case 13; hereinafter, the space formed in this way is referred to as a “side surface space”). Are communicating. For this reason, the liquefied electrolytic solution is accumulated between the inner case 13 and the outer case 5 (that is, the bottom side space S1, the gap space S2, and the side surface space S3), and the outflow of the electrolytic solution to the outside is prevented.

  As described above, according to this embodiment, the capacitor body 1 is fixed by the fixture 3 provided on the inner bottom portion of the outer case 5, and the fixture 3 is made of the gaseous electrolytic solution ejected from the explosion-proof valve 131. It is made of a material that promotes liquefaction (non-gaseous). For this reason, when an abnormal load such as an overvoltage is applied to the electrolytic capacitor and the explosion-proof valve 131 is activated, liquefaction of the gaseous electrolytic solution ejected from the explosion-proof valve 131 is promoted, and the liquefied electrolytic solution becomes the inner case 13. Between the outer case 5 and the outer case 5. Thus, since the fixture 3 for fixing the capacitor body 1 to the outer case 5 also has a function of preventing the electrolyte from flowing out to the outside, the electrolyte can be used when the explosion-proof valve is operated with a simple and inexpensive structure. Can be prevented from flowing out to the outside.

<Others>
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the said embodiment, although the protrusion part 32 of the fixing tool 3 is provided in four places around the annular part 31, it is not limited to this, It is good also as three places or less and five places or more. In short, it is only necessary that the fixture 3 can contact the inner case 13 to fix the capacitor body 1.

  Moreover, in the said embodiment, although the fixing tool 3 is formed with the porous material, it is not limited to this, The material (henceforth a "gelling agent" containing the gelatinizer which makes the fixing tool 3 gelatinize electrolyte solution) It may be formed of “containing material”). In this case, the gaseous electrolytic solution ejected from the explosion-proof valve 131 is gelated by contacting the fixture 3 made of the gelling agent-containing material, and the liquefied electrolytic solution is interposed between the inner case 13 and the outer case 5 (that is, The bottom surface side space S1, the gap space S2, and the side surface space S3) are accumulated. Thereby, the outflow of the electrolyte solution to the outside is prevented. Thus, since the fixture 3 formed of the gelling agent-containing material also has a function of preventing the electrolyte from flowing out to the outside, it has a simple and inexpensive structure, and the electrolyte is discharged to the outside during the operation of the explosion-proof valve. Outflow can be prevented. The gelling agent is not particularly limited as long as it has heat resistance and can be applied to and mixed with a fixture. For example, polycarboxylic acid or a salt thereof (such as ammonium polycarboxylate), cellulose, cellulose nitrate Cellulose derivatives consisting of alkali metal salts of cellulose acetate, hydroxyalkyl cellulose, alkyl cellulose, carboxyalkyl cellulose, alkali metal salts of alginic acid, gelatin, agar, konjac flour, starch, polysaccharides, protein, polyvinyl alcohol, polyvinyl alcohol derivatives, For thickeners such as polyvinyl ether derivatives, polyvinyl acetate, vinyl acetate-vinyl alcohol copolymer, sodium carboxymethylcellulose, pectin, guar gum, xanthan gum, tamarind gum, carrageenan It is.

  In addition to the gelling agent, a material that promotes reliquefaction of the gaseous electrolyte may be used. For example, by forming the fixture with a material containing a solute component of an electrolytic solution such as boric acid, the gaseous electrolyte ejected from the explosion-proof valve 131 is applied to the fixture formed of a material containing a solute component of the electrolytic solution. The electrolytic solution that has been contacted, reliquefied, and liquefied accumulates between the inner case 13 and the outer case 5. Thereby, the outflow of the electrolyte solution to the outside is prevented.

  Moreover, in the said embodiment, although the explosion-proof valve is formed in the bottom face of the inner case 13, the formation site | part of an explosion-proof valve is not limited to this. For example, an explosion-proof valve may be formed on the side surface of the inner case 13.

  The present invention can be applied to an electrolytic capacitor that prevents the ejected matter ejected from the explosion-proof valve from flowing out even when the explosion-proof valve is activated.

It is a figure which shows one Embodiment of the electrolytic capacitor concerning this invention. It is a figure which shows the structure of the fixing tool with which the electrolytic capacitor shown in FIG. 1 was equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Capacitor main body 3 ... Fixing tool 5 ... Exterior case 7 ... Sealing material (external sealing material)
7a ... Lead insertion hole 11 ... Capacitor element 12 ... Lead wire 13 ... Inner case 15 ... Sealing material (internal sealing material)
15a ... Lead insertion hole 31 ... Ring portion 32 ... Projection 131 ... Explosion-proof valve (weak body)
S1 ... bottom side space S2 ... gap space S3 ... side surface side space

Claims (4)

Capacitor having a capacitor element impregnated with an electrolytic solution, a bottomed cylindrical inner case in which the capacitor element is housed and formed with a weak body portion, and an inner sealing material for sealing the opening of the inner case In a double case structure electrolytic capacitor in which the main body is housed in an exterior case having a space larger than the volume of the internal case inside, and the opening of the external case is sealed with an external sealing material,
A fixing tool for fixing the capacitor body to the outer case on the inner bottom of the outer case;
The electrolytic capacitor, wherein the fixture is made of a material that promotes degasification of the gaseous electrolytic solution ejected from the weak body portion.   The electrolytic capacitor according to claim 1, wherein the fixture is made of a porous material.   The electrolytic capacitor according to claim 1, wherein the fixture includes a gelling agent that gels the electrolytic solution. The electrolytic capacitor according to claim 1, wherein the weak body portion is formed on a bottom surface of the inner case.
The electrolytic capacitor according to claim 1, wherein the fixing member is formed in an annular shape surrounding the bottom surface of the inner case so that the weak body portion faces the inner bottom surface of the exterior case.

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