| 摘要 |
An ignition coil for developing spark plug firing voltages. The magnetic current for the ignition coil comprises an axially extending core (32A,34B) that joins axially spaced annular parts (32B,34D). The core and parts can be formed of iron particles in a binder of electrical insulating material. A primary winding (36) is disposed about the core and a secondary winding (40) is disposed about the primary winding. An axially extending circular part (72) that is formed of magnetic material is positioned to provide air gaps (86,87) with outer surfaces (32D,34E) of said annular parts. The circular part forms a shield that increases the capacitance of the secondary winding. The total stored magnetic energy does not vary substantially with variations in air gap length. The cross-sectional area A of the air gap is large as compared to the length L of the air gap so that the ratio A/L does not vary much with variations in L. |
