| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive spark plug, in which a noble metal chip is firmly bonded to a center electrode body, and the high-temperature wear of the noble chip is suppressed. SOLUTION: The spark plug 100, for the internal combustion engine, has a ring-bonding part 123. The noble metal chip 121 has a contact plane 121b contacting the center electrode body 122 at ordinary temperature, or a contact plane 121b directly contacting to the center electrode body 122 before the noble metal chip 121 become a high temperature. The cross section Sb of the noble metal chip 121 and the cross section Sc of the bonding part 123 have the relation 1/10≤Sc/Sb≤1/2. In the bonding part 123, the depth T, as measured from the out lateral side plane 121d of the noble metal chip 121 to an axial line C is not less than 0.05 (mm) on the first fictional line K1, passing the point of the intersection P1 of the contact plane 123 and the axial line C and intersecting right angles to the axial line C. COPYRIGHT: (C)2005,JPO&NCIPI
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