| 摘要 |
PROBLEM TO BE SOLVED: To make it possible not to cause a defect by which a water droplet penetrates into a coil, although in a prior art closed magnetic path type ignition coil, the cross sectional area of a magnet connecting a central iron core and an outer peripheral iron core is made wide to improve the magnetic performance of the iron cores, but in a boundary part where the cross sectional area of the central iron core becomes wider, because the facing surface between the central iron core and a primary coil is made in the vertical direction to the opening surface of a case, a crack of mold resin spreads to the opening surface of the case due to peeling between the central iron core and the primary coil caused by the difference of thermal expansion coefficients between the central iron core and the primary coil.SOLUTION: In an ignition coil for an internal combustion engine 100 in which at least one cross sectional area of outer peripheral iron core connection parts 32b, 32c magnetically connected to an outer peripheral iron core 40 among a central iron core 30 is wider than the cross sectional area of a coil arrangement part 32a, the opening surface 62 side parts of a case 60 of the outer peripheral iron core connection parts 32b, 32c are covered with protrusions 14a, 14b, 22a, 22b formed on a primary bobbin 10 or a secondary bobbin 20. |
