| 摘要 |
<p>PROBLEM TO BE SOLVED: To increase igniting energy by a method wherein strip shaped silicon steel plates having different widths are stacked, the outer shape is formed to approach a circle so that a central iron core is formed, and the diameter of the circle enveloping the outer shape of the central iron core is defined. SOLUTION: A central iron core 11 of an ignition coil 10 is so formed that its outer shape is approximate to a circle by laminating strip shaped silicon steel plates 11' different in width. A non-directional plate can be used for the silicon steel plates 11', but a directional magnetic plate is more preferable. Regarding the diameter D of an enveloping circle O of the outer configuration of the central iron core 11, the diameter D is obtained by multiplying a square of the outer diameter of a sheath iron core by a number from 0.017 to 0.020. Regarding the lengths of the central iron core 11 and the sheath iron core, the central iron core 11 is shorter than the sheath iron core, and both ends of the central iron core 11 are made not to protrude from both ends in the length direction of the sheath iron core.</p> |
