A spark plug for an internal combustion engine

摘要

In a spark plug (1) for an internal combustion engine, an insulator (2) has a concentric axial bore (2a) in which a center electrode (3) is placed with a front end (3a) of the center electrode extending beyond a front end portion (2b) of the insulator. A metallic shell (4) is placed to support the insulator (2). An outer electrode (5) is connected to a front end (4a) of the metallic shell (4) to form a spark gap (G) with the front end portion (3a) of the center electrode (3). At least an outer surface of the outer electrode (5) is formed by a smoothly curved profile so as to smoothly run air-fuel mixture along the outer electrode (5). <IMAGE> <IMAGE>