| 摘要 |
PROBLEM TO BE SOLVED: To smoothly discharge even if a center electrode is worn by energizing the center electrode in the direction projecting from the tip of a base part with a spring, and locking the projection from the base part with a locking plate of a gap setting rod. SOLUTION: A specified gap (d) is formed between a locking plate 7 of a gap setting rod 6 and an L-shaped side electrode 3 arranged directly under a center electrode 2 from the side of a base part 1. With increase in the number of times of discharge, the center electrode 2 wears from the tip, the center electrode 2 is pushed out in the projecting direction with a spring 13, and projection from the base part 1 is obstructed with the locking plate 7 of the gap setting rod 6. The tip of the center electrode 2 is locked with the locking plate 7 of the gap setting rod 6 independent of wear, and the gap (d) to the side electrode 3 is kept constant. Discharge between the center electrode 2 and the side electrode 3 is well conducted independent of wear of the center electrode.
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