Patent ID: 7239224

Claim:
An ignition coil comprising: a primary coil; a secondary coil that is arranged substantially coaxially with respect to the primary coil; a spool that has a substantially cylindrical shape, one of the primary coil and the secondary coil being an inner coil arranged on an inner side of an other of the primary coil and the secondary coil, the inner coil being wound around the spool; and a center core that is located on an inner side of the spool, wherein the spool has a tapered inner surface, which is defined at least partially in the spool with respect to an axial direction of the spool, the tapered inner surface has a diameter that increases as being distant from a high voltage tip end of the secondary coil, the high voltage tip end of the secondary coil being on a high voltage side of the secondary coil, the center core has a tapered outer surface, which is defined at least partially in the center core with respect to an axial direction of the center core, the tapered outer surface has a diameter that increases as being distant from the high voltage tip end of the secondary coil, the tapered inner surface of the spool is opposed to the tapered outer surface of the center core with respect to a substantially radial direction of the center core, wherein the secondary coil has a low voltage tip end on a low voltage side of the secondary coil, and the low voltage tip end of the center core has a large diameter portion, which has an outer diameter largest of the center core, the low voltage tip end of the spool has a first contact inner surface that is adapted to making contact with the large diameter portion of the center core, so that the center axis of the center core is adjustable, and the high voltage tip end of the spool has a second contact inner surface that is adapted to making contact with a high voltage tip end of the center core, so that the center axis of the center core is adjustable.