Patent ID: 7190249

Claim:
An ignition coil comprising: an exciting core provided with a primary coil and a secondary coil which are wound therearound; a closed magnetic path forming core which is in contact with this exciting core and adapted to pass a magnetic flux generated from said coils; and a permanent magnet provided at a position between said exciting core and said closed magnetic path forming core, wherein both said cores have a substantially square shape in cross section, and include at least two contact positions, contact faces of a first contact position being formed by a first face of said exciting core and a first face of said closed magnetic path forming core, contact faces of a second contact position being formed by a second face of said exciting core which is directed to a different direction from said first face and a second face of said closed magnetic path forming core which is directed to a different direction from said first face, and that said permanent magnet is arranged between the contact faces of either one of the contact positions, and wherein, both the cores are formed by laminating a plurality of thin plates in a same direction, said closed magnetic path forming core including at least a first closed magnetic path forming core formed of said laminated thin plates which have a first shape and a second closed magnetic path forming core formed of laminated thin plates which have a second shape partly different from the first shape, the contact faces of the first contact position are formed by a first face of the exciting core and a first face of said first closed magnetic path forming core, said permanent magnet being arranged between the contact faces of the first contact position, while the contact faces of the second contact position are formed by a second face of the exciting core and a second face of said first closed magnetic path forming core, and further, a third contact position is formed adjacent to said second contact position between a third face of said exciting core and the first face of said second closed magnetic path forming core.