| 摘要 |
PROBLEM TO BE SOLVED: To provide a glow plug allowing a metal ring and a ceramic heater to be simply assembled and having satisfactory reliability. SOLUTION: In a disassembled state in which the first and the second terminal rings 14 and 3 are detached from the ceramic heater 1, the ten-point mean roughness Rz1 of fit surfaces 41a and 41b on the sides of the first and the second terminal rings 14 and 3 is made 11μm or below. Moreover, in the disassembled state, the ten-point height of irregularities Rz2 of the fit surfaces 42a and 42b on the ceramic heater 1 side is made 5μm or below. Thus, the tight fit of the ceramic heater 1 and the first and second terminal rings 14 and 3 is performed well.
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