Capacitor assembly of the wound-foil type

Abstract

This capacitor assembly includes inner and outer sheets of metal foil constituting first and second electrodes, respectively, of the assembly and dielectric film interposed between the foil sheets and insulating the foil sheets from each other when the capacitor assembly is energized. The foil sheets and the dielectric film are wound about a central axis to form a roll in which the sheets and the film are disposed in interleaving turns extending about the central axis in face-to-face relationship. Each of the foil sheets has a head edge near the central axis and a tail edge near the outer periphery of the roll. The head and tail edges of the inner foil sheet are folded over to reduce electric-field stress concentrations adjacent these edges. But the head and tail edges of the outer foil sheet are left unfolded, and the outer foil sheet adjacent its head and tail edges extends about the central axis substantially beyond the respective head and tail folded edges of the inner foil sheet. As between the above two foil sheets, the foil sheet nearer to the outer periphery of the roll is considered to be the outer foil sheet.