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1. (WO2017037969) SPARK PLUG

Pub. No.:    WO/2017/037969    International Application No.:    PCT/JP2016/002771
Publication Date: Fri Mar 10 00:59:59 CET 2017 International Filing Date: Thu Jun 09 01:59:59 CEST 2016
IPC: H01T 13/20
H01T 13/32
Applicants: NGK SPARK PLUG CO., LTD.
Inventors: SUZUKI, Kaori
鈴木 かおり
KATO, Tomoaki
加藤 友聡
In the present invention, warping of a discharge tip relative to an electrode material is suppressed, the discharge tip being laser welded onto the electrode material and provided with a discharge layer and an intermediate layer. The spark plug has the discharge layer, which contains a precious metal or a precious metal alloy positioned on a central electrode side, and an intermediate layer having one end joined to the discharge layer and at least a portion of the other end joined to an electrode base material interposed by a fusing part and containing a smaller amount of a precious metal element than the discharge layer, the precious metal element being the most abundant of the precious metal elements included in the discharge layer. The fusing part is formed at least in an area farther to the other end side of the electrode parent material than the center of the discharge layer when the discharge tip is viewed from the axial direction. In a cross section parallel to the axial direction and including the center line along the longitudinal direction of a grounding electrode, the proportion of the length along the longitudinal direction of the fusing part over the range in which the discharge tip is present along the longitudinal direction, relative to the length of the discharge tip along the longitudinal direction of the electrode parent material, is at least 76.2%.