DE19721342C1 - Sealed electrolytic capacitor prevented from drying out and loss of function - Google Patents

Abstract

This novel multilayer material seals the top of an electrolytic condenser can (2). The substrate is sandwiched by an outer elastomeric layer and an internal sealing layer. An additional spacer layer lies between the substrate and inner sealing layers. This is an elastomer, or other rubbery material. Preferably the same elastomer forms spacer layer and covering. The spacer layer is ethylene propylene terpolymer. The substrate is an impregnated paper multilayer and the sealing layer is polypropylene. Phenolic resin forms the impregnation. Layers are pressed together and cross-linked or vulcanised. The sealing layer may be coated-on subsequently. The spacer layer is up to 50% of the thickness of the covering layer.

Description

The invention relates to a capping material for Closing an electrolytic capacitor that in the is essentially designed as a sealing cover, which has a multilayer structure and at least a carrier, an elastomeric top layer and a sealing layer arranged facing away from the cover layer having.

Such covers serve the interior an electrolytic capacitor to the environment seal and ver leakage of the electrolyte avoid. Typically, the housings are made of such Electrolytic capacitors from an aluminum cup, the  a circumferential profile protruding into the interior has, on which the closure lid rests. By a flanging of the edge becomes the cover fixed against the circumferential profile and against these pressed.

From JP 08306596 A (Patent Abstracts of Japan 1996) is already a capping material for closing an electrolytic capacitor known that one more layered structure. On a poly carrier propylene are a top layer and a sealing layer upset. Both layers consist of an elasto mer rubber-like material.

From US 34 28 869 is another capping Material known for electrolytic capacitors. Also this capping material has several layers on, which are connected to a carrier.

The sealing caps that have become known so far can not yet meet all the requirements for a optimal sealing of the electrolytic capacitor will. Especially with larger manufacturing tolerances There may be leaks in the area of the capacitor housing to step.

The object of the present invention is therefore a Capping material of the type mentioned in the introduction to improve such that regardless of manufacturing tolerances an optimal sealing effect is provided.

This object is achieved in that a spacer layer is arranged between the carrier and the cover layer and that the spacer layer is made of an elastomer or a rubber-like material.
The additional elastomer layer has two major advantages. On the one hand, an elasticity is provided in the area of support of the sealing cap by the circumferential profile of the capacitor housing, which improves a sealing effect, particularly with rounded contours in the area of the peripheral profile and in the event of manufacturing tolerances. In addition, an additional sealing along an upper flank of the peripheral profiling is brought about.

When flanging the edge of the cup-shaped Housing is the cover with the elastic Spacer layer against the top flank of the circumference profiling pressed so that the pressure force immediately converted into a contact pressure in the sealing area becomes. With the sealing caps according to the state of the The sealing effect is achieved by means of a radial Directionally pressing out the top layer as well by contact of the hard carrier with the circumference profiling achieved.

The second major advantage is a ver greater spring action due to the elastic inherent of the spacer layer. As a result, the shock resistance or back the resilience of the closure lid is increased and even if on within a wide operating range reliable sealing under supports. In addition, an increased seal is applied the connection contacts achieved.

This can result in a simplified manufacturing process be achieved that the spacer layer from the same elastomer as the cover layer.

A particularly proven selection of materials is that the spacer layer made of ethylene-propylene terpolymer is trained.

To provide high resistance to a variety of electrolytes is proposed that the sealing layer is made of polypropylene.

This can result in high mechanical resistance achieved that the carrier from an impregnated Paper layer is formed.  

To provide a composite structure is pre suggest that the paper layer be made up of several layers stands.

A high mechanical stability and cheap elec This means that trotechnical properties can interact with each other be combined that the carrier with phenolic resin is impregnated.

To further improve the sealing effect will struck that the top layer the carrier laterally overhanging.

A secure connection of the individual layers of the Ver end cover can be supported that the Carrier, the top layer and the spacer layer with pressed together and vulcanized. Can also the sealing layer can be groove-related.

Finally, a typical dimensioning is that the Spacer layer has a thickness that is up to 50% of The thickness of the top layer is.

Exemplary embodiments of the invention are shown in the drawing shown schematically. Show it:

Fig. 1 is a plan view showing a disposed in the region of a can housing closure lid,

Fig. 2 shows a cross section along section line AA in Fig. 1 and

Fig. 3 shows a cross section along section line BB in Fig. 2 with an exclusive representation of the closure cover.

From the illustration in Fig. 1 it can be seen that an electrolytic capacitor ( 1 ) with a cup-shaped Ge housing ( 2 ) is provided, which holds a cover ( 3 ). The sealing cover ( 3 ) carries connection contacts ( 4 , 5 ).

From the cross-sectional view in Fig. 2 it can be seen that the housing ( 2 ) encloses an interior ( 6 ). The housing ( 2 ) has a circumferential profile ( 7 ), which protrudes web-like in the interior ( 6 ) and provides a bearing surface ( 8 ) for the closure cover ( 3 ). The edge ( 9 ) of the housing ( 2 ) is flanged in such a way that the sealing cover ( 3 ) is pressed between the edge ( 9 ) and the bearing surface ( 8 ). At the circuit contacts ( 4 , 5 ) are stabilized by washers ( 10 , 11 , 12 , 13 ).

From the cross-sectional view in Fig. 3 it can be seen that the closure cover ( 3 ) has a multilayer construction. A cover layer ( 15 ) and a spacer layer ( 16 ) are held by a carrier ( 14 ). In the installed state, the cover layer ( 15 ) faces away from the interior ( 6 ) and the spacer layer ( 16 ) faces the interior ( 6 ). The spacer layer ( 16 ) is in the area of the carrier ( 14 ) facing away from a sealing layer ( 17 ) pulled over. The sealing layer ( 17 ) prevents the electrolyte from penetrating into the region of the spacer layer ( 16 ) and the carrier ( 14 ).

The cover layer ( 15 ) and the spacer layer ( 16 ) are typically made of elastomers. For example, rubber-like materials are used. In particular, the use of ethylene-propylene terpolymer is contemplated. In particular, it is also possible to form the cover layer ( 15 ) and the spacer layer ( 16 ) from the same elastomer.

A polypropylene coating or a Teflon coating, for example, can be used as the sealing layer ( 17 ). The specific choice of materials depends on the chemical properties of the electrolyte.

An impregnated paper layer can be used as the carrier ( 14 ), for example. In particular, it is contemplated to form the paper layer from several layers of paper. Phenolic resin can be used as an impregnating agent.

Fig. 3 shows in particular that the cover layer ( 15 ) laterally overhangs the carrier ( 14 ). Through an overhang ( 18 ) an improved sealing effect is achieved.

The cover layer ( 15 ) typically has a somewhat smaller thickness than the carrier ( 14 ). The spacer layer ( 16 ) typically has a thickness in the range up to 50% of the cover layer ( 15 ). In particular, it is contemplated to see the spacer layer ( 16 ) approximately with a fifth of the thickness of the cover layer ( 15 ). The sealing layer ( 17 ) is very thin relative to the carrier ( 14 ) and typically has a thickness of at most 1% of the thickness of the carrier ( 14 ).

According to a conventional manufacturing process, plates are first produced in which the carrier ( 14 ), the cover layer ( 15 ) and the spacer layer ( 16 ) and the sealing layer ( 17 ) are pressed together and vulcanized under the action of temperature and pressure. The sealing layer ( 17 ) can alternatively be applied in a subsequent production step. After completion of the plate production, the United cover ( 3 ) are punched out of the plates.

According to a typical dimensioning, the carrier ( 14 ) has a thickness of approximately 1.5 mm, the cover layer ( 15 ) has a thickness of 1.0 mm and the spacer layer ( 16 ) is approximately 0.25 mm thick Mistake. The sealing layer ( 17 ) has a thickness of at most 0.1 mm.

Claims (11)

1. capping material for closing an electrolytic capacitor, which is essentially designed as a sealing cover, which has a multilayer structure and has at least one carrier, an elastomeric cover layer and a cover layer arranged facing away from the cover layer, characterized in that between the carrier ( 14 ) and the sealing layer ( 17 ) is arranged a spacer layer ( 16 ) and that the spacer layer ( 16 ) is formed from an elastomer or a rubber-like material. 2. capping material according to claim 1, characterized in that the spacer layer ( 16 ) from the same elastomer as the cover layer ( 15 ) is formed. 3. capping material according to claim 1 or 2, characterized in that the spacer layer ( 16 ) is formed from ethylene-propylene terpolymer. 4. capping material according to one of claims 1 to 3, characterized in that the sealing layer ( 17 ) is formed from polypropylene. 5. capping material according to one of claims 1 to 4, characterized in that the carrier ( 14 ) is formed from an impregnated paper layer. 6. capping material according to claim 5, characterized ge indicates that the paper layer consists of several Layers. 7. capping material according to one of claims 1 to 6, characterized in that the carrier ( 14 ) is impregnated with phenolic resin. 8. capping material according to one of claims 1 to 7, characterized in that the cover layer ( 15 ) laterally overhangs the carrier ( 14 ). 9. capping material according to one of claims 1 to 8, characterized in that the carrier ( 14 ), the cover layer ( 15 ) and the spacer layer ( 16 ) and the seal are pressed together and vulcanized. 10. capping material according to one of claims 1 to 8, characterized in that the carrier ( 14 ), the cover layer ( 15 ) and the spacer layer ( 16 ) and the seal are pressed together and vulcanized and that the sealing layer ( 17 ) after the vulcanization process is applied. 11. capping material according to one of claims 1 to 10, characterized in that the spacer layer ( 16 ) has a thickness which is up to 50% of the thickness of the cover layer ( 15 ).