| 摘要 |
PROBLEM TO BE SOLVED: To improve heat dissipation through a path from an insulator, via a plate packing, to a main metal fitting, in a spark plug.SOLUTION: In a spark plug, the relation between: a length A obtained by the addition of the length A1 of the contact between a plate packing and a main metal fitting in a cross-section of one side and the length A2 of the contact between the plate packing and an insulator on the one side; the length B obtained by the addition of the length B1 of the contact between the plate packing and the main metal fitting in a cross-section of the other side and the length B2 of the contact of the plate packing and the insulator in a cross-section of the other side; and the difference M obtained by the subtraction of the inside diameter D of a shelf part from the inside diameter C of a hollow part, satisfies 2.8≤(A+B)/M. |
