| 摘要 |
<p>PROBLEM TO BE SOLVED: To secure stable output characteristics even when a gap between an ignition coil main body and a non-permeable material is narrow, by setting a specific cross-section area ratio between an outside layer iron core provided on the outer periphery of a coil and a center iron core. SOLUTION: A center iron core 23 assigned on a cylinder axis of a plug hole, a secondary coil 222 which, on the outside periphery of the center iron core 23, wound in vertical direction against a longitudinal direction of the center iron core 23, and a primary coil 222 wound coaxially, on its outer periphery, with the secondary coil 222, are provided. The secondary coil 222 is wound on a secondary bobbin 223, and the primary coil 212 is wound on a primary bobbin 211. Between the coils and a case 27, the first outside layer iron core 40 and the second outside layer iron core 42 are provided. The cross-section area ratio formed between the first and second outside layer iron cores 40 and 42 is 70% of the center iron core 23 or above. Thereby, the attenuation in output characteristics after insertion in the plug hole is set about 7%, for stable output characteristics.</p> |
