| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the plasma generation efficiency by increasing the capacitive-discharge current without changing the shape of a spark plug significantly or providing a capacitor outside. <P>SOLUTION: A spark plug 1 comprises an electrical insulator 2 having an axial hole 4, a center electrode 5, and a main fitting 3, and has a cavity portion 28 formed by the inner surface of the axial hole 4 and the tip surface of the center electrode 5. At least a portion of at least one of the outer surface of the electrical insulator 2 facing the inner surface of the main fitting 3, and the inner surface of the electrical insulator 2 facing the outer surface of the center electrode 5, is provided with a conductive layer 31 or 32 composed of a conductive material, the conductive layer 31 on the outer surface of the electrical insulator 2 is electrically connected to a ground electrode 27, and the conductive layer 32 on the inner surface of the electrical insulator 2 is electrically connected to the center electrode 5. <P>COPYRIGHT: (C)2012,JPO&INPIT |
