Spark plug having a noble metal electrode portion
AssigneeNgk Spark Plug Co., Ltd.
InventorsWataru Matsutani, Junichi Kagawa
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Abstract
In a spark plug, a cylindrical metallic shell has a tubular insulator in which a columnar center electrode is place, a front end of the center electrode extending beyond the insulator. A nobel metal portion is thermally bonded to an outer wall of the front end of the center electrode by means of laser beams so as to form a spark gap between the noble metal portion and a ground electrode which is extended from the metallic shell. The noble metal portion has a molten alloy layer in which the center electrode is melted into the noble metal portion, and a diffused alloy layer in which the noble metal portion is diffused into the center electrode, so that the molten alloy layer forms a spark discharge surface against a front end of the ground electrode.
Claims3
A spark plug comprising:
- a cylindrical metallic shell having a tubular insulator in which a columnar center electrode is placed, a front end of the center electrode extending beyond the insulator;
- a noble metal portion bonded to an outer side wall of the front end of the center electrode by means of laser beams so as to form a spark gap between the noble metal portion and a ground electrode which is extended from the metallic shell;
- the noble metal portion having a molten alloy layer in which the center electrode is melted into the noble metal portion, and a diffused alloy layer in which the noble metal portion is diffused into the center electrode, so that the molten alloy layer forms a spark discharge surface against a front end of the ground electrode.
Dependencies are inferred from the claim text.