| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug capable of properly suppressing the generation of pre-ignition caused by an air fuel mixture stayed in a plug pocket.SOLUTION: A spark plug 1A has a housing part 2A, an insulator 3 held in the housing part 2A, a center electrode 4 exposed from the insulator 3, and a ground electrode 5 forming a discharge gap part G between the center electrode 4 and the ground electrode, and a plug pocket P is provided between the housing part 2A and the insulator 3. The spark plug 1A has a region R1 that is not processed to enlarge its area, at a part adjacent to the plug pocket P in the housing part 2A, and a region R2 that is processed to enlarge its area. The region R2 is located at the tip side in an axial direction with respect to the region R1. |
