Ignition coil having a circular core and a method of making the same

Abstract

An ignition coil contains an elongated substantially circular coil core which includes a primary coil and a secondary coil each disposed radially outwardly of the core with the core composed of a plurality of generally rectangular elements at least some of which have a different width than others and the elements being in surface-to-surface contact with each other. The lateral walls of the elements may have a shape which is not perpendicular to the longitudinal extent of the elements. The core may be welded at its ends. A core contained within this ignition coil, which may be an automotive ignition coil, is disclosed. A method of making such an ignition coil may include providing a plurality of generally rectangular elongated generally flat metal elements, at least some of which have different widths than others, assembling the elements with the element of greatest widths toward the center and those of progressively reduced widths being on opposed sides thereof, and mechanically machining the lateral edges of at least a majority of the elements to create a coil assembly having a circular or substantially circular core shape. The core assembly may be deburred, and smears removed to create a smooth exterior shape and joined as by welding. The core has a greater weight for a given diameter than one of comparable diameter which has a stepped configuration.