GB2063564A

GB2063564A - A ceramic capacitor

Info

Publication number: GB2063564A
Application number: GB8034257A
Authority: GB
Original assignee: Draloric Electronic GmbH
Current assignee: Draloric Electronic GmbH
Priority date: 1979-11-02
Filing date: 1980-10-23
Publication date: 1981-06-03
Also published as: FR2468984A1; DE2944394A1; JPS5674914A

Abstract

A ceramic capacitor comprises a cylindrical pot shaped dielectric body (1) covered on its inner surface (5) and its outer surface (8) with metal layers (6', 6''), respectively, the metal layers (6', 6'') being separated electrically by a metal free bead (10) on the outer surface of the dielectric body (1), and a connection element (4', 4'') fixed to each metal layer (6', 6''), the base (3) of the dielectric body (1) being reentrant and projecting into the central cavity (2) of the dielectric body to form a pot shaped insert. <IMAGE>

Description

SPECIFICATION A ceramics capacitor The invention relates to a ceramics capacitor comprising a cylindrical pot shaped dielectric body covered on its inner and outer surface with a metal layer, the two metal layers being electrically separated from each other by means of a metal-free bead on the outer surface of the dielectric body; and a connection element being fixed to each metal layer.

These capacitors are known for example from the Applicants' cataloque "Keramik Leistungskondensatoren" ("Ceramics Power Capacitors"), 3 A 5.78. These may be cooled by air or water, the water-cooled capacitors in particular have a cooling liquid flowing round them at their outer sleeve surface. In this known embodiment of water-cooled capacitors, the whole of the outer sleeve surface is not cooled; the edge of the bead remains uncooled. Moreover, the central cavity of the pot-shaped capacitors is not used either for cooling or to increase the capacitance value.

The invention therefore seeks to make available a pot-shaped ceramics capacitor in which the central cavity is used to increase the capacitance of the capacitor.

According to the invention there is provided a ceramics capacitor comprising a cylindrical pot-shaped dielectric body covered on its inner and outer surface with a metal layer, the two metal layers being electrically separated from each other by means of a metal-free bead on the outer surface of the dielectric body; and a connection element being fixed to each metal layer wherein the base of the potshaped dielectric body is reentrant and projects into the central cavity of the dielectric body to provide a pot-shaped insert.

The advantages achieved by the invention consists more particularly of utilizing the stranded ceramic material out of which the dielectric body is hollowed (which is known as "Hubel" in Germany) more efficiently, because the waste due to turning on a lathe is substantially reduced and also that a capacitor of fairly large capacitance may be produced per unit volume with a strand of ceramics of fixed diameter and fixed length. A further advantage lies in the enlarged surface area and in the resultant improved dissipation of heat to the surroundings or to the cooling liquid which also cools the encircling bead during internal cooling.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1. shows, partly in section, a multipie (pot) capacitor in accordance with the invention uncooled, and Figure 2. shows a water-cooled power capacitor in accordance with the invention.

Fig. 1. shows an air-cooled ceramic capacitor, the dielectric body 1 of which is hollowed out of a leather-tough strand of ceramic and comprises three cylindrical parts oppositely oriented alternately which are coated on their inner surface 5 and on their outer surface 8 with a metal layer or coating 6' or 6" respectively. A bead 10 separates the two coatings 6' and 6" from each other. A connecting element 4' is welded firmly to the metal layer of the inner of the inner coating 6' and projects beyond the open end face 7 of the pot capacitor. A second connecting element 4" is welded firmly to the metal layer of the outer coating 6". This connecting armature 4" may be located at the outer sleeve surface or on the base 3 of the dielectric body 1.

Fig. 2 shows an internally cooled power capacitor comprising a pot-shaped dielectric body 1, the base 3 of is reentrant and projects into the central cavity 2 to form a potshaped insert. The inner surface 5 and the outer surface 8 are covered with a metal layer or a coating 6', 6" respectively, which metal layers are electrically insulated from each other by means of a bead 10. A connecting armature 4' is fixed to the end face 7 of the dielectric body 1 in a water-tight manner, two connecting pieces 9' and 9" for the circulation of cooling medium projecting out of this element. A connecting armature 4" is welded firmly to the base 3 of the dielectric body 1 for the second coating 6".

The capacitor in accordance with the invention may be uncooled, internally cooled and/or externaily cooled. The invention is not limited to the embodiment of dielectric bodies shown, but rather applies quite generally to pot capacitors having many reentrant pot shaped portions within each other.

1. A ceramic capacitor comprising a cylindrical pot-shaped dielectric body covered on its inner and outer surface with a metal layer, the two metal layers being electrically separated from each other by means of a metal-free bead on the outer surface of the dielectric body; and a connection element being fixed to each metal layer, wherein the base of the potshaped dielectric body is reentrant and projects into the central cavity of the dielectric body to provide a pot-shaped insert.

2. A ceramics capacitor according to Claim 1, wherein the base of the pot-shaped insert it itself reentrant and projects into the cavity of the insert to provide a further potshaped insert.

3. A ceramics capacitor according to Claim 1 or 2, wherein the connection element for the coating located on the inner surface is firmly welded to the free end face of the dielectric body.

4. A ceramics capacitor according to any one of Claims 1 to 3, wherein the connecting element for the coating located on the outer

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A ceramics capacitor The invention relates to a ceramics capacitor comprising a cylindrical pot shaped dielectric body covered on its inner and outer surface with a metal layer, the two metal layers being electrically separated from each other by means of a metal-free bead on the outer surface of the dielectric body; and a connection element being fixed to each metal layer. These capacitors are known for example from the Applicants' cataloque "Keramik Leistungskondensatoren" ("Ceramics Power Capacitors"), 3 A 5.78. These may be cooled by air or water, the water-cooled capacitors in particular have a cooling liquid flowing round them at their outer sleeve surface. In this known embodiment of water-cooled capacitors, the whole of the outer sleeve surface is not cooled; the edge of the bead remains uncooled. Moreover, the central cavity of the pot-shaped capacitors is not used either for cooling or to increase the capacitance value. The invention therefore seeks to make available a pot-shaped ceramics capacitor in which the central cavity is used to increase the capacitance of the capacitor. According to the invention there is provided a ceramics capacitor comprising a cylindrical pot-shaped dielectric body covered on its inner and outer surface with a metal layer, the two metal layers being electrically separated from each other by means of a metal-free bead on the outer surface of the dielectric body; and a connection element being fixed to each metal layer wherein the base of the potshaped dielectric body is reentrant and projects into the central cavity of the dielectric body to provide a pot-shaped insert. The advantages achieved by the invention consists more particularly of utilizing the stranded ceramic material out of which the dielectric body is hollowed (which is known as "Hubel" in Germany) more efficiently, because the waste due to turning on a lathe is substantially reduced and also that a capacitor of fairly large capacitance may be produced per unit volume with a strand of ceramics of fixed diameter and fixed length. A further advantage lies in the enlarged surface area and in the resultant improved dissipation of heat to the surroundings or to the cooling liquid which also cools the encircling bead during internal cooling. The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1. shows, partly in section, a multipie (pot) capacitor in accordance with the invention uncooled, and Figure 2. shows a water-cooled power capacitor in accordance with the invention. Fig. 1. shows an air-cooled ceramic capacitor, the dielectric body 1 of which is hollowed out of a leather-tough strand of ceramic and comprises three cylindrical parts oppositely oriented alternately which are coated on their inner surface 5 and on their outer surface 8 with a metal layer or coating 6' or 6" respectively. A bead 10 separates the two coatings 6' and 6" from each other. A connecting element 4' is welded firmly to the metal layer of the inner of the inner coating 6' and projects beyond the open end face 7 of the pot capacitor. A second connecting element 4" is welded firmly to the metal layer of the outer coating 6". This connecting armature 4" may be located at the outer sleeve surface or on the base 3 of the dielectric body 1. Fig. 2 shows an internally cooled power capacitor comprising a pot-shaped dielectric body 1, the base 3 of is reentrant and projects into the central cavity 2 to form a potshaped insert. The inner surface 5 and the outer surface 8 are covered with a metal layer or a coating 6', 6" respectively, which metal layers are electrically insulated from each other by means of a bead 10. A connecting armature 4' is fixed to the end face 7 of the dielectric body 1 in a water-tight manner, two connecting pieces 9' and 9" for the circulation of cooling medium projecting out of this element. A connecting armature 4" is welded firmly to the base 3 of the dielectric body 1 for the second coating 6". The capacitor in accordance with the invention may be uncooled, internally cooled and/or externaily cooled. The invention is not limited to the embodiment of dielectric bodies shown, but rather applies quite generally to pot capacitors having many reentrant pot shaped portions within each other. CLAIMS

4. A ceramics capacitor according to any one of Claims 1 to 3, wherein the connecting element for the coating located on the outer surface is fixed to the sleeve surface or to the base of the dielectric body.

5. A ceramic capacitor according to any one of Claims 1 to 4, wherein the connecting element for the inner coating seals the central cavity in a water-tight manner and has a connecting piece for a supply of cooling medium and a connecting piece for the outlet of cooling medium.

6. A ceramic capacitor according to any one of Claims 1 to 4, wherein the dielectric body is located up to the metal-free bead in a cylindrical cooling element having a base seal and connected conductively to the outer coating; and the cooling element has a connecting piece for the supply of cooling medium and a connecting piece for the outlet of cooling medium.

7. A ceramic capacitor according to Claim 5 or 6, wherein the central cavity and the outer surface of the dielectric body are cooled.

8. A ceramic capacitor substantially as described herein with reference to the drawings.