| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug or a sensor element in which a loss (burn-off) of electrode material caused by spark discharge is reduced so that a change of an interval between electrodes is reduced. SOLUTION: A spark plug for an internal combustion engine or a sensor element for an ignition or a combustion process has electrodes 102, 103. An interval 105 between first parts 101 of the electrodes 102, 103 is smaller than an interval between the other parts 104 of the electrodes 102, 103. In at least one of the electrodes 102, 103, a material of the first part 101 is different from a material of the other part 104. At least one of the electrodes 102, 103 has a small curvature radius in a portion where the interval 105 between the first parts 101 of the electrodes 102, 103 is minimal. Moreover, at least one of the electrodes 102, 103 can have a protrusion 106 in a portion facing to a portion of the other electrode 103, 102 in which sediments can be generated in operation.
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