| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent cracking from occurring in a thermosetting insulating resin layer starting from the edge faces of an open magnetic circuit iron core due to a linear expansion coefficient difference between the iron core and the resin layer so as to protect an ignition coil against dielectric breakdown when the open magnetic circuit iron core is buried in a thermosetting insulation resin layer. SOLUTION: An open magnetic circuit iron core 3 is arranged at the inner center of a cylindrical resin case 4 which is long and small in diameter and possessed of a holding cylinder 7 that faces rearward and a high-voltage terminal 6 both located at its closed front, the front end of the open magnetic circuit iron core 3 is inserted into the holding cylinder 7 located at the closed front of the cylindrical resin case 4, a primary coil 1 and a secondary coil 2 both shorter than the iron core 3 are concentrically provided to the iron core 3 making the primary coil 1 located inside the secondary coil 2 and the centers of the coils 1 and 2 nearly coincident with that of the iron core 3. The primary coil 1, the secondary coil 2, and the iron core 3 except its rear edge are buried in a thermosetting insulating resin layer 10 which is potted halfway in the resin case 4, a crack-resistant insulating resin layer 11 is provided between the thermosetting insulating resin layer 10 and the rear edge of the resin case 4, and the rear edge of the iron core 3 is buried in the crack-resistant insulating resin layer 11.</p> |
