JPH0655241U - Electrolytic capacitor - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the leakage of electrolytic solution at the aluminum rivet part of large electrolytic capacitors. In an electrolytic capacitor using an aluminum rivet 11 on a sealing plate 6 in which a bake plate 7 and an elastic sheet 8 are bonded together, the aluminum rivet 11 is attached to the head part 1 of the electrolytic capacitor.
The protrusion 11c is provided on the surface of the la 1a on the side of the shaft 11b. Further, when the aluminum rivet 11 was inserted into the sealing plate 6, the projection 11c fixed the elastic sheet 8 so as to press it. With this configuration, the adhesion strength between the aluminum rivet 11 and the sealing plate 6 is increased, so that the electrolytic solution is less likely to leak.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention relates to improvement of the structure of aluminum rivets used in large electrolytic capacitors.

[0002]

[Prior art]

 There are large and small electrolytic capacitors, and their structures are different. Among them, the general structure of a large electrolytic capacitor is as follows.

As shown in FIG. 3, a band-shaped anode 2 made of aluminum has an oxide film layer serving as a dielectric formed on the surface thereof. Then, the anode 2 is wound together with the separator 4 and the cathode foil 3 which are formed in a strip shape to form a cylindrical capacitor element 1. A strip-shaped tab 9 connected to the electrode foils of the anode 2 and the cathode 3 is drawn out from the upper end surface of the capacitor element 1. The capacitor element 1 is impregnated with an electrolytic solution, and the capacitor element 1 impregnated with the electrolytic solution is housed in an outer case 5 having a cylindrical shape with a bottom.

The tip of the strip-shaped tab 9 is fixed to the aluminum rivet 11 mounted in the through hole provided in the sealing body 6 for sealing the opening of the outer case 5 by crimping or welding. . The aluminum rivet 11 is connected to the external terminal 10 on the outer surface of the sealing plate. Generally, the aluminum rivet 11 is formed of a head and a shaft. Further, the through hole provided in the sealing plate is also formed as a through hole having a diameter substantially the same as the diameter of the shaft portion of the aluminum rivet 11 so as to match with the shaft portion of the aluminum rivet 11.

The sealing plate 6 is composed of a baking plate 7 made of phenolic resin and an elastic sheet 8 made of rubber or the like attached to the sealing plate 6. The opening end of the outer case 5 is tightened to bite into the elastic sheet 8 for sealing. Has been done.

[0006]

[Problems to be solved by the device]

 By the way, in the electrolytic capacitor, the electrolytic solution may leak out from the caulking portion of the sealing plate 6 and the outer case 5, the sealing body 6 itself, or the gap between the aluminum rivet 11 and the through hole of the sealing body 6. If the electrolytic solution leaks out, it may adhere to the printed circuit board itself on which the electrolytic capacitor is mounted or other electronic components mounted at the same time, which may have an unfavorable effect, which is extremely inconvenient.

It is also known that the leakage of the electrolytic solution deteriorates the electrical characteristics of the electrolytic capacitor. The electrolyte enters the etching pits formed innumerably on the surface of the anode foil of the electrolytic capacitor, and the oxide film of the anode foil serves as a dielectric and functions as a true cathode. Therefore, if the electrolytic solution leaks out and decreases, the contact area with the dielectric layer decreases, and as a result, the capacitance of the electrolytic capacitor decreases. Further, the electrolytic solution has a function of re-forming the oxide film layer on the surface of the anode when the oxide film layer on the surface of the anode is damaged or deteriorated to repair the oxide film layer. Therefore, the leakage of the electrolyte causes a decrease in the self-repairing power of the oxide film, which causes current flow from the anode to the cathode, that is, an increase in leakage current. Deterioration of these electrical characteristics is a factor that determines the life of electrolytic capacitors.

Therefore, in this invention, leakage of the electrolytic solution at the aluminum rivet portion of the large electrolytic capacitor is reduced, and the electrical characteristics and life characteristics of the electrolytic capacitor are improved.

[0009]

[Means for Solving the Problems]

 The electrolytic capacitor of this invention is an electrolytic capacitor in which an aluminum rivet is used as a sealing plate made by bonding a hard insulating plate and an elastic member, and a projection is provided on the shaft side surface of the head of the aluminum rivet and the aluminum rivet is also used. When the is inserted into the sealing plate, the aluminum rivet is fixed while the protrusion is pressed against the elastic member.

[0010]

[Action]

 A protrusion is provided on the shaft side surface of the head of the aluminum rivet used in a large electrolytic capacitor, and when the aluminum rivet was inserted into the sealing body, the protrusion fixed so as to press the elastic member. In the section, the elastic member is pressed with a relatively stronger force than the flat section of the head of the aluminum rivet. Therefore, sufficient adhesion strength can be obtained between the protrusion and the elastic member. On the other hand, in the flat part of the head of the aluminum rivet, the force pressing the elastic member is relatively weak, so that the load applied to the elastic member can be reduced. Therefore, the elastic member has little deterioration in elasticity over time, and can retain the elasticity for a long period of time.

As described above, since the elastic force of the elastic member is less deteriorated over time, the adhesion strength between the aluminum rivet and the elastic member can be maintained for a long period of time. Therefore, the leakage of the electrolytic solution at the aluminum rivet can be prevented for a long period of time.

[0012]

【Example】

 Next, this invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an electrolytic capacitor of the present invention, and FIG. 2 is an enlarged sectional view of an essential part of the electrolytic capacitor of the present invention.

As shown in FIG. 1, a capacitor element 1 is composed of a strip-shaped aluminum foil, an anode 2 having an oxide film formed on its surface, and a cathode 3 also made of a strip-shaped aluminum foil, which is wound via a separator 4. It is rotated and formed into a cylindrical shape. A strip-shaped tab 9 is electrically connected to each of the anode 2 and the cathode 3, and each tab 9 is drawn out from the upper end surface of the capacitor element 1. Then, the capacitor element 1 is impregnated with an electrolytic solution and is housed in a bottomed cylindrical outer case 5 made of aluminum.

As shown in FIG. 2, a sealing plate 6 for sealing the electrolytic capacitor is formed by laminating a bake plate 7 made of phenol resin and an elastic sheet 8 made of rubber, and the bake plate 7 side is the inside of the electrolytic capacitor. The elastic sheet 8 is used so as to come outside the electrolytic capacitor. The sealing plate 6 is formed with a through hole for inserting the aluminum rivet 11. Further, as shown in FIG. 4, the aluminum rivet 11 inserted into the through hole of the sealing plate 6 is formed with a shaft portion 11b following the head portion 11a, and further, the shaft portion 11b side of the head portion 11a. A protrusion 11c is formed on the surface so as to surround the shaft 11b. Further, the shaft portion 11b is formed with substantially the same diameter as the through hole provided in the sealing plate 6, so that when the aluminum rivet 11 is inserted into the through hole of the sealing plate 6, there is almost no gap between them.

Then, the external terminal 10 is attached to the aluminum rivet 11. The external terminal 10 is formed in an L-shape, and is connected to the flat portion of the head portion 11a of the aluminum rivet 11 opposite to the shaft portion 11b side by means such as laser welding or spot welding. Further, as the shape of the external terminal 10, the L-shaped external terminal 10 is used in this embodiment, but an external terminal 15 formed in a V shape as shown in FIG. 5 is used. Good.

The aluminum rivet 11 to which the external terminal 10 is attached is inserted into the through hole of the sealing plate 6, and at this time, pressure is applied so that the protrusion 11c of the aluminum rivet 11 presses the elastic sheet 8 of the sealing plate 6. Inserted.

A through hole having substantially the same diameter as the shaft portion 11b of the aluminum rivet 11 is formed at the tip of the tab 9 pulled out from the capacitor element 1. The tab 9 is inserted into the lower end portion of the aluminum rivet 11 inserted into the sealing body 6 together with the washer 12, and then the lower end of the aluminum rivet 11 is pressed to attach the tab 9 to the aluminum rivet 11. In this way, the aluminum rivet 11 is firmly attached to the sealing plate 6 by caulking the lower end of the aluminum rivet 11 by pressing. Then, the sealing plate 6 is housed in the outer case 5, the opening end of the outer case 5 is wound and tightened, and the opening end is bite into the elastic sheet 8 of the sealing plate for sealing.

When the electrolytic capacitor is configured as described above, the protrusion 11c is provided on the surface of the head 11a of the aluminum rivet 11 on the side of the shaft portion 11b, and the protrusion 11c is pressed against the elastic sheet 8. The protrusion 11c and the elastic sheet 8 firmly adhere to each other. Therefore, when the electrolytic solution impregnated in the capacitor element 1 leaks through the gap between the through hole of the sealing plate 6 and the aluminum rivet 11 inserted in the through hole, the aluminum rivet 11 and the sealing plate 6 firmly adhere to each other. Since it has to pass through the place where the electrolyte flows, the electrolyte does not leak easily.

In the embodiment described above, the aluminum rivet 11 having the shape of the aluminum rivet in which the projection 11c is provided so as to surround the shaft portion 11b on the surface of the head portion 11a on the shaft portion 11b side has been described. The invention is not limited to the above embodiments. As another embodiment of this invention, for example, as shown in FIG. 6, the aluminum rivet 14 has four protrusions 11d on the surface of the head 11a on the side of the shaft 11b so as to surround the shaft 11b. It may be provided. Further, the shape of the protrusion may be a hemispherical tip, or the entire protrusion may be tapered, and can be arbitrarily set. Further, the number of protrusions and the positions of the protrusions formed on the aluminum rivet are not particularly limited, and can be set arbitrarily according to design specifications.

[0020]

[Effect of device]

 As described above, in the electrolytic capacitor of the present invention, the projection is provided on the shaft side surface of the head of the aluminum rivet, and the projection presses the elastic member when the aluminum rivet is inserted into the sealing body. Since it is fixed in this way, the protrusion presses the elastic member with a relatively stronger force than the flat part of the head of the aluminum rivet. Therefore, sufficient adhesion strength can be obtained between the protrusion and the elastic member. On the other hand, in the flat part of the head of the aluminum rivet, the force pressing the elastic member is relatively weak, so that the load applied to the elastic member is small. Therefore, the elastic member has little deterioration in elastic force over time, and can retain the elastic force for a long period of time.

As described above, since the elastic member has less deterioration in elastic force over time, the aluminum rivet and the elastic member can maintain the adhesion strength for a long period of time. Therefore, the leakage of the electrolytic solution at the aluminum rivet can be prevented for a long period of time.

Since the electrolytic solution does not leak to the outside of the electrolytic capacitor, it may adversely affect other electronic components mounted at the same time as the electrolytic capacitor and a printed circuit board on which the electrolytic capacitor is mounted. Disappears.

[Brief description of drawings]

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

FIG. 2 is an enlarged sectional view showing a main part of the electrolytic capacitor of the present invention.

FIG. 3 is a cross-sectional view showing a conventional electrolytic capacitor.

FIG. 4 is a perspective view showing an aluminum rivet used in the present invention.

FIG. 5 is a perspective view showing a “U” -shaped external terminal used in the electrolytic capacitor of the present invention.

FIG. 6 is a perspective view showing another embodiment of the aluminum rivet used in the electrolytic capacitor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode 3 Cathode 4 Separator 5 Exterior case 6 Sealing plate 7 Baking plate 8 Elastic sheet 9 Tabs 10, 15 External terminals 11, 14 Aluminum rivets 11a Head 11b Shafts 11c, 11d Protrusions 12 Washers

Claims (1)

[Scope of utility model registration request] 1. An electrolytic capacitor in which an aluminum rivet is used as a sealing plate obtained by bonding a hard insulating plate and an elastic member together, and a projection is provided on the shaft side surface of the head of the aluminum rivet, and the aluminum rivet is sealed. An electrolytic capacitor, wherein the aluminum rivet is fixed in a state in which the protrusion is pressed against the elastic member when inserted into a plate.