| 摘要 |
The purpose of the present invention is to achieve superior resistance to contamination in a spark plug in which the main body hardware is reduced in diameter without increasing the length of a leg part. A spark plug (1) is provided with an insulator (2) and main body hardware (3) that has a threaded part (15) with a thread diameter of M12 or less and that is provided on the outer periphery of the insulator (2). The insulator (2) is provided with a latching part (14) that latches to a stepped part (21) of the main body hardware (3) via sheet packing (22), and a leg part (13) that forms a clearance (33) with the inside peripheral surface of the main body hardware (3). Letting L (mm) be the distance toward the tip end side from tip part (22E) of the sheet packing (22) and A (mm) be the size of the clearance (33), the position at which the size A is 0.5 mm or less is more to the back end side than the position that includes a position 2.0 mm from the tip part (22E) to the tip end side. In addition, in a range of 3.0 <= L <= 4.0, A >= L × 0.2 + 0.2 (mm) is satisfied. |
