| 摘要 |
PURPOSE:To suppress flux leakage and maintain the required ignition performance of an ignition coil which has a permanent magnet in its magnetic path while the size increase is avoided. CONSTITUTION:A primary coil 12 is wound around the first leg parts 2a and 3a of a pair of U-shaped cores 2 and 3 and a secondary coil 22 is wound around the second leg parts 2b and 3b and a permanent magnet 5 is provided in the primary coil 12. It is preferable to place the permanent magnet 5 at the center part of the axial direction of the primary coil 12. It is recommanded to have the area ratio Sm/Sc of the cross sectional area Sm of the permanent magnet 5 and the minimum cross sectional area Sc of cores 2 and 3 1.8 Tesla/Br, wherein Br denotes a residual flux density. |
