Patent GB-611900-A (GB)
Title: Improvements in or relating to electrical condensers
IPC: H01G13/02
Filed: 1946-05-13
Abstract: 611,900. Condensers. DUBILIER CONDENSER CO. (1925), Ltd., COURSEY, P. R., MUNDAY, C. H., and GOUGH, K. A. May 13, 1946, Nos. 14428, 36201 and 36202. [Class 37] The core of a rolled electrical condenser comprises a wire or thread preferably of a diameter not exceeding 0.1 inches and more preferably of the order of 0.015 to 0.030 inches, held under tension between aligned rotary chucks driven in synchronism during the manufacture of the condenser. When the core A of the condenser, Fig. 10, is electrically conductive, an interleaved metal foil C1 is connected to the core A and a second interleaved metal foil C2 finally laps the outer surface of the rolled condenser, paper strips D1 and D2 being suitably interleaved whilst a terminal tag G is wound into the rolled unit beneath the outer metal foil C2. One end of the core is cut off flush with the rolled unit, the remaining projecting end of the core constituting one electrical terminal whilst the terminal tag constitutes the second electrical terminal. Severalmethods of housing the rolled unit are described. According to one method, the rolled unit is inserted into a conducting sleeve closed at one end, except for a small hole through which the projecting core of the unit may extend with suitable insulating means, the other end of the sleeve being closed by means of an insulating disc with an outer metal terminal disc soldered over the open mouth of the sleeve. Alternatively, the rolled unit may be housed in an open-ended cylinder, the end of the cylinder through which the core projects being sealed with ceramic material, whilst the other end of the cylinder is sealed as described above, or, alternatively, the above open-ended cylinder may have its ends spun over the sealing means described. In a further modification, a strip of tinned copper K, Fig. 14, having a terminal tag K1, is arranged around a rolled unit such that the tag K1 is positioned at the end of the unit from which the core A has been severed, a terminal wire A7 is soldered to the tag K1 to lie in axial alignment with, but spaced from the cylindrical unit. When the core comprises one or more threads of insulating material, a paper strip is first secured to the core and the two strips of metal foil and the second paper strip are then wound about the core. A unit rolled by this method is wholly lapped on its outer surface by the second paper strip and is wound such that one metal foil strip projects from one end of the rolled unit and the second metal foil strip projects from the opposite end of the rolled unit. After the condenser has been rolled, the projecting ends of the core are removed and the unit is inserted into a ceramic tube and sealed with pig-tail terminal leads pressed against the metal foils. All the above units are preferably treated with chlorinated naphthalenes, chlorinated diphenyls or hydrogenated or hydroxylated products of castor oil. Any of the constructions described may be moulded into a housing of insulating material such as that sold under the Registered Trade Mark " Bakelite." Specification 590,757 is referred to.